Sadhana Ravishankar

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Scholarly Contributions

Chapters

• Rao, A., & Ravishankar, S. (2019). Alternatives to pest and disease control in pre-harvest, and washing and processing in post-harvest levels for organic produce. In Safety and Practice for Organic Food. Cambridge, MA: Elsevier.
• Taylor, T. M., Ravishankar, S., Bhargava, K., & Juneja, V. K. (2019). Chemical Preservatives and Natural Food Antimicrobials. In Food Microbiology Fundamentals and Frontiers 5th Edition(pp 705-731). Washington D. C.: ASM Press.
• Ravishankar, S. (2018). Plant-Based Antimicrobials for Clean and Green Approaches to Food Safety. In Natural and Bio-Based Antimicrobials for Food Applications(pp 45-61). Washington, DC: American Chemical Society. doi:10.1021/bk-2018-1287
• Dev Kumar, G., Ravishankar, S., & Juneja, V. (2017). Preservation Methods for Fruits and Vegetables.. In Microbial Control and Food Preservation: Theory and Practice. New York: Springer.
• Ravishankar, S. -., & Juneja, V. K. (2013). Sodium chloride.. In Encyclopedia of Food Microbiology. Elsevier, Philadelphia, PA.
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  Ravishankar, S., and Juneja, V. K. 2013. Sodium chloride. (Invited Book Chapter). In Encyclopedia of Food Microbiology. Eds: Batt, C. and Tortorello, M. L. Elsevier, Philadelphia, PA.

Journals/Publications

• Arellano, S., Law, B., Friedman, M., & Ravishankar, S. (2021). Essential oil microemulsions inactivate antibiotic-resistant Salmonella Newport and spoilage bacterium Lactobacillus casei on Iceberg lettuce during 28-day storage at 4° C.. Food Control, 130, 108209.
• Chen, C. H., Marchello, J., Friedman, M., & Ravishankar, S. (2021). Plant Extracts and Essential Oils at Concentrations Acceptable to a Sensory Panel Inactivate Salmonella Typhimurium DT104 in Ground Pork. Food and Nutrition Sciences, 12, 162-175.
• Joshi, K., Sparks, P., Friedman, M., Olsen, C., McHugh, T., & Ravishankar, S. (2021). Effect of Antimicrobial Edible Films on the Sensory and Physical Properties of Organic Spinach in Salad Bags. Food and Nutrition Sciences, 12, 176-193.
• Reyna-Granados, J., Joens, L., Law, B., Friedman, M., & Ravishankar, S. (2021). Antimicrobial Effects of Plant Compounds against Virulent Escherichia coli O157:H7 Strains Containing Shiga Toxin Genes in Laboratory Media and on Romaine Lettuce and Spinach.. Food and Nutrition Sciences, 12, 392-405.
• Zhu, L., Wei, Q., Porchas, M., Brierley, P., Friedman, M., Crosby, K., Patil, B., & Ravishankar, S. (2021). Plant-based antimicrobials inactivate Listeria monocytogenes and Salmonella enterica on melons grown in different regions of the United States. Food Microbiology, 101, 103876.
• Fonseca, J. M., Ravishankar, S., Sanchez, C. A., Park, E., & Nolte, K. D. (2020). Assessing the Food Safety Risk Posed by Birds Entering Leafy Greens Fields in the US Southwest. International journal of environmental research and public health, 17(23).
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  In the US Southwest, it is common to observe birds in leafy green fields, though the risk they contribute to foodborne outbreaks remains unclear. In this study, we investigated and recorded the relationship between birds near leafy green fields and the risk for contaminated irrigation water or leafy green plants. We monitored the presence of birds for over two years and performed cloacal swab analysis for non-pathogenic , O157:H7 and , while also monitoring the incidence of other microbial indicators. We also assessed the risks from bird feces by performing observations in a commercial field reported with positive samples and by analyzing the survival of foodborne pathogens in bird feces. Our results showed that most of the birds near the crop fields were resident small birds. We did not observe a correlation between the number of birds in sites and the incidence of indicator bacteria (e.g., coliforms, ) in irrigation canal water, with the exception of one out of four sites where water flow was low or stagnant. Using walk-in-traps, 305 birds were captured and placed in short-term captivity to determine the presence of various bacteria. None of the birds tested positive for O157:H7 or . However, nearly 40% of the birds captured were confirmed positive for non-pathogenic . We found no correlation between age (young, adult, unknown), gender (male, female, unknown) and the incidence of positive birds, but we observed significantly higher probability of incidence during October-December. The role of relative humidity and temperature on bacterial survival appeared to play a key role in the survival of on the leaves of spinach plants in a commercial field. This was also confirmed in laboratory conditions where inoculated in bird feces and exposed to 15 °C and 80% RH(Relative humidity) survived beyond 133 days, while at 26 °C and 40% RH, the organism was undetectable after 63 days. Our results suggest that local birds associated with leafy green fields likely pose a minimal impact of risk for food contamination, but also points out the need for increased analysis specifically for O157:H7. Furthermore, our study suggests the need for expanding research that addresses risks associated with large migratory birds, especially in areas where stagnated water sources would be used for overhead sprinkle irrigation.
• Kumar, G. D., Patel, J., & Ravishankar, S. (2020). Contamination of spinach at germination: A route to persistence and environmental reintroduction by Salmonella. International journal of food microbiology, 326, 108646.
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  The effects of using contaminated seed and water on the persistence and internalization of Salmonella Newport in organic spinach cultivars- Lazio, Space, Emilia and Waitiki were studied. Seeds were contaminated by either immersing in a suspension of Salmonella and then sprouted or were sprouted in Salmonella contaminated water in the dark at 25 °C. After 5 days, germinated sprouts were analyzed for S. Newport population and internalization. Germinated sprouts were potted in soil and grown in a plant incubator for 4 weeks. Leaves, stems and roots were sampled for Salmonella population by plating on CHROMagar™. Plants surface-sterilized with chlorine were analyzed for internalized pathogen. Potting soil and water runoff were sampled for Salmonella after 4 weeks of plant growth. Contaminated seeds and irrigation water had S. Newport populations of 7.64±0.43 log CFU/g and 7.12±0.04 log CFU/ml, respectively. Sprouts germinated using contaminated water or seeds had S. Newport populations of 8.09±0.04 and 8.08±0.03 log CFU/g, respectively and had a Salmonella population that was significantly higher than other spinach tissues (P
• Singh, J., Metrani, R., Jayaprakasha, G. K., Crosby, K. M., Ravishankar, S., & Patil, B. S. (2020). Multivariate Analysis of Amino Acids and Health Beneficial Properties of Cantaloupe Varieties Grown in Six Locations in the United States. Plants (Basel, Switzerland), 9(9).
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  Cantaloupe is a good dietary source of amino acids, including γ-aminobutyric acid (GABA), glutamine, and citrulline. However, the levels of these amino acids vary among different cantaloupe varieties grown in different locations. Understanding the variation in amino acid contents provides fundamentally important information for quality control and improving melon varieties. To examine this variation, we measured the amino acid contents in cantaloupes grown in six locations in the United States (Texas, Georgia, North Carolina, California, Indiana, and Arizona). Principal component analyses were applied to analyze the effect of growing location on the amino acid profiles in different varieties. The GABA content ranged from 1006.14 ± 64.77 to 3187.12 ± 64.96 µg/g and citrulline ranged from 92.65 ± 9.52 to 464.75 ± 34.97 µg/g depending on the variety and location. Total phenolic contents, α-amylase inhibition, and antioxidant activities were also measured. Tuscan type Da Vinci had significantly higher phenolic contents in Arizona (381.99 ± 16.21 µg/g) but had the lowest level when grown in California (224.56 ± 14.62 µg/g). Our analyses showed significant differences in amino acid levels, phenolics contents, and antioxidant activity in the cantaloupe varieties based on the growing location. These findings underline the importance of considering growing location in the selection and improvement of cantaloupe varieties.
• Vitha, S., & Ravishankar, S. (2020). Surface texture analysis of melon rind using 3D reconstruction from SEM stereo images.. Texas Journal of Microscopy, 51(1), 24.
• Wei, Q., Zhan, Y., Chen, B., Xie, B., Fang, T., Ravishankar, S., & Jiang, Y. (2020). Assessment of antioxidant and antidiabetic properties of Murill extracts. Food science & nutrition, 8(1), 332-339.
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  Murill (ABM), a medicinal mushroom, has beneficial effects on various human metabolic diseases. The objective of this research was to evaluate the antioxidant and antidiabetic properties of ABM extracts (ethanol extract and ethyl acetate extract). The antioxidant activities of ABM ethanol extract (EE) and ethyl acetate extract (EA) were analyzed using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and hydroxyl radical scavenging assays and the reducing power using KFe(CN) in vitro. Moreover, the effects of EE and EA on α-glucosidase inhibitory activity and improving glucose uptake by HepG2 cells were investigated in vitro. The EA showed stronger antioxidant activity, as well as inhibition of α-glucosidase, compared to EE. The analysis of glucose uptake by HepG2 cells showed that EA had significant glucose-lowering activity and exhibited no difference compared to metformin. The results suggest that ABM extracts could improve the glucose uptake by HepG2 cells and thereby alleviate postprandial hyperglycemia. This investigation provides a strong rationale for further studies on the application of ABM to control type 2 diabetes.
• Zhu, L., Olsen, C., McHugh, T., Friedman, M., Levin, C., Jaroni, D., & Ravishankar, S. (2020). Edible films containing carvacrol and cinnamaldehyde inactivate Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags.. Journal of Food Safety, e12758, 1-7.
• Bright, K. R., Ravishankar, S., & Gilling, D. H. (2019). Antimicrobial efficacy of plant essential oils and extracts against Escherichia coli. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A - TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING, 54(7), 608-616. doi:https://doi.org/10.1080/10934529.2019.1574153
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  The efficacies of 11 plant-derived antimicrobials were evaluated against Escherichia coli in vitro in solution at room temperature. These included lemongrass, cinnamon, and oregano essential oils and their active components (citral, cinnamaldehyde, and carvacrol, respectively). Allspice and clove bud oils and olive, green tea, and grape seed extracts were also studied. The efficacies of the antimicrobials were both concentration- and exposure time-dependent. The essential oils and their active components demonstrated statistically significant >5.0-log10 reductions within 1-10 min. The plant extracts were less effective; green tea and grape seed extracts required 24 h before significant reductions were observed (1.93-log10 and 5.05-log10, respectively). Nevertheless, olive extract exhibited a reduction of ∼5-log10 within 30 min. Most of these plant-derived compounds exhibited strong bactericidal activity and can potentially be applied as alternatives to chemicals for foods/food contact surfaces since they are generally recognized as safe (GRAS) for human consumption. They may also be useful in applications in which other antimicrobials have reduced efficacy (e.g., in the presence of organics) or used with sensitive populations that are unable to tolerate exposure to harsher chemicals (e.g., elderly care facilities). These compounds could be used alone, in combination, or with fast-acting antimicrobials to provide a long-lasting residual.
• Dev Kumar, G., & Ravishankar, S. (2019). Ozonized water with plant antimicrobials: An effective method to inactivate Salmonella enterica on iceberg lettuce in the produce wash water. Environmental Research, 171, 213-217.
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  Post-harvest washing of produce is performed to remove physical debris and to lower microbial load. The use of ozone in combination with plant-based antimicrobials was evaluated as an alternative to conventional sanitizers such as chlorine. Plant based antimicrobials that were evaluated in combination with ozone included oregano oil, carvacrol, Quillaja saponin and olive extract. Ozone was dispersed in phosphate buffered saline (PBS), following which individual antimicrobials or their combinations were added. Iceberg lettuce leaves (10 g portions) inoculated with Salmonella enterica serotype Newport (6.5 ± 1 log CFU/g) were added to the wash suspension. The leaves were tested for reduction in S. Newport population after 60, 90 and 120 min of treatment. Exposure to ozonized water for 120 min resulted in a 2.1 log CFU/g (p 
• Gilling, D. H., Ravishankar, S., & Bright, K. R. (2019). Antimicrobial efficacy of plant essential oils and extracts against Escherichia coli. Journal of Environmental Science and Health. Part A, Toxic/hazardous substances & environmental engineering, 54(7), 608-616.
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  The efficacies of 11 plant-derived antimicrobials were evaluated against in solution at room temperature. These included lemongrass, cinnamon, and oregano essential oils and their active components (citral, cinnamaldehyde, and carvacrol, respectively). Allspice and clove bud oils and olive, green tea, and grape seed extracts were also studied. The efficacies of the antimicrobials were both concentration- and exposure time-dependent. The essential oils and their active components demonstrated statistically significant >5.0-log reductions within 1-10 min. The plant extracts were less effective; green tea and grape seed extracts required 24 h before significant reductions were observed (1.93-log and 5.05-log, respectively). Nevertheless, olive extract exhibited a reduction of ∼5-log within 30 min. Most of these plant-derived compounds exhibited strong bactericidal activity and can potentially be applied as alternatives to chemicals for foods/food contact surfaces since they are generally recognized as safe (GRAS) for human consumption. They may also be useful in applications in which other antimicrobials have reduced efficacy (e.g., in the presence of organics) or used with sensitive populations that are unable to tolerate exposure to harsher chemicals (e.g., elderly care facilities). These compounds could be used alone, in combination, or with fast-acting antimicrobials to provide a long-lasting residual.
• Govindaraj, D. K., Zhu, L., Siemens, M. C., Nolte, K. D., Brassill, N. A., Rios, D., Galvez, R., Fonseca, J. M., & Ravishankar, S. (2018). Modified Coring Tool Designs Reduce Iceberg Lettuce Cross-Contamination. J. Food Protection, 82(3), 454-462.
• Kumar, G. D., Zhu, L., Siemens, M. C., Nolte, K., Brassill, N., Rios, D. V., Galvez, R., Fonseca, J. M., & Ravishankar, S. (2019). Modified Coring Tool Designs Reduce Iceberg Lettuce Cross-Contamination. Journal of Food Protection, 82(3), 454-462.
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  Contaminated coring tools may transfer bacteria to iceberg lettuce. The efficiency of coring tool design modifications in reducing bacterial transfer to lettuce heads was evaluated under simulated field operations. The standard coring tool consists of a stainless steel cylindrical tube welded to a tab that is inserted into a plastic handle. Design modifications included removal of the welded portion, incorporation of a shorter front straight bottom edge, or an angled bottom edge toward the front. In the first study, coring tools of four different designs were inoculated by dipping in a tryptic soy broth (TSB) suspension that contained 8.85 Log CFU/mL of Escherichia coli K-12 and then were used to core 100 lettuce heads, consecutively. Use of the standard tool resulted in 91% ± 9% positive lettuce heads. Removing the welded surface from the standard tool resulted in the highest reduction of E. coli transfer (44% ± 11.9% positive lettuce heads, P < 0.05), whereas incorporation of a short front straight edge with no welding resulted in 65.6% ± 5.6% of the cored lettuce heads being positive for E. coli. Removal of the welded surface resulted in a 40% decrease in E. coli contamination among the last 20 cored lettuce heads (81 to 100), which indicates that coring tool design modifications resulted in reduced cross-contamination. In the second study, the transfer of Salmonella to coring tools after their immersion in rinsing solutions was evaluated using imaging. The tools were dip inoculated for 2 min in water, water with lettuce extract, or TSB containing 7 Log CFU/mL bioluminescent Salmonella Newport; they were then imaged to observe spatial distribution of bacteria. There was greater retention and spatial distribution of Salmonella on the surface of tools immersed in water containing lettuce extract than in TSB and water. The results of the second study indicate that rinsing solutions that contain lettuce particulate and organic load could facilitate cross-contamination of Salmonella Newport to tool surfaces.
• Panthi, S., Sapkota, A. R., Raspanti, G., Allard, S. M., Bui, A., Craddock, H. A., Murray, R., Zhu, L., East, C., Handy, E., Callahan, M. T., Haymaker, J., Kulkarni, P., Anderson, B., Craighead, S., Gartley, S., Vanore, A., Betancourt, W. Q., Duncan, R., , Foust, D., et al. (2019). Pharmaceuticals, herbicides, and disinfectants in agricultural water sources. Environmental Research, 174, 1-8.
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  Agricultural water withdrawals account for the largest proportion of global freshwater use. Increasing municipal water demands and droughts are straining agricultural water supplies. Therefore, alternative solutions to agricultural water crises are urgently needed, including the use of nontraditional water sources such as advanced treated wastewater or reclaimed water, brackish water, return flows, and effluent from produce processing facilities. However, it is critical to ensure that such usage does not compromise soil, crop, and public health. Here, we characterized five different nontraditional water types (n = 357 samples) for the presence of pharmaceuticals, herbicides, and disinfectants using ultra-high-pressure liquid chromatography tandem mass spectrometry based method (UPLC-MS/MS). We then evaluated whether the levels of these contaminants were influenced by season. The highest level of herbicides (atrazine) was detected in untreated pond water (median concentration 135.9 ng/L). Reclaimed water had the highest levels of antibiotics and stimulants including azithromycin (215 ng/L), sulfamethoxazole (232.1 ng/L), and caffeine (89.4 ng/L). Produce processing plant water also tended to have high levels of atrazine (102.7 ng/L) and ciprofloxacin (80.1 ng/L). In addition, we observed seasonal variability across water types, with the highest atrazine concentrations observed during summer months, while the highest median azithromycin concentrations were observed in reclaimed water during the winter season. Further studies are needed to evaluate if economically feasible on-farm water treatment technologies can effectively remove such contaminants from nontraditional irrigation water sources.
• Zhu, L., Torres, M., Betancourt, W. Q., Sharma, M., Micallef, S. A., Gerba, C., Sapkota, A. R., Sapkota, A., Parveen, S., Hashem, F., May, E., Kniel, K., Pop, M., & Ravishankar, S. (2019). Incidence of fecal indicator and pathogenic bacteria in reclaimed and return flow waters in Arizona, USA. Environmental Research, 170, 122-127.
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  The quality of irrigation water used to cultivate produce that is consumed raw is an important issue with regard to food safety. In this study, the microbiological quality of potential irrigation water sources in Arizona was evaluated by testing for the presence of indicator and pathogenic bacteria. Reclaimed water samples were collected from two wastewater treatment plants and return flow samples were collected from two drainage canals and one return flow pond. Standard membrane filtration methods were used for detection of indicator bacteria. Water samples (n = 28) were filtered through cellulose ester membrane filters and bacterial populations were enumerated by placing the filters on selective agar. For detection of pathogens (Salmonella enterica, Listeria monocytogenes and Shiga toxin-producing E. coli (STEC)), water samples were filtered through Modified Moore swabs and enriched in Universal Pre-enrichment Broth, followed by selective enrichment broth for each pathogen. The enriched broth was streaked onto agar media selective for each pathogen. Presumptive colonies were confirmed by PCR/real-time PCR. Among the 14 reclaimed water samples from two sites, the ranges of recovered populations of E. coli, total coliforms, and enterococci were 0-1.3, 0.5-8.3 × 10, and 0-5.5 CFU/100 mL, respectively. No L. monocytogenes, Salmonella or STEC were found. In the 13 return flow water samples from 3 sites, the ranges of recovered populations of E. coli, total coliforms and enterococci were 1.9-5.3 × 10, 6.5 × 10-9.1 × 10, and 2.9-3.7× 10 CFU/100 mL, respectively. All samples were negative for L. monocytogenes. One (7.1%) of the return flow samples was positive for E. coli O145. Nine (64.3%) of the samples were positive for Salmonella. Both real-time PCR and culture-based methods were used for the detection of Salmonella and L. monocytogenes, and the results from the two methods were comparable. The findings of this study provide evidence that irrigation waters in Arizona, including reclaimed water and return flows, could be potential sources of bacterial contamination of produce. Additional work is needed to evaluate whether bacteria present in irrigation water sources transfer to the edible portion of irrigated plants and are capable of persisting through post-harvest activities.
• Cordery, A., Rao, A. P., & Ravishankar, S. (2018). Antimicrobial Activities of Essential Oils, Plant Extracts and their Applications in Foods- A Review.. Journal of Agriculture and Environmental Sciences, 7, 76-89.
• Pinoargote, G., & Ravishankar, S. (2018). Effects of salinity on acid production and growth of three probiotic microbes with potential for application in intensive shrimp aquaculture.. Journal of Probiotics & Health, 6(1), 191. doi:10.4172/2329-8901.1000191.
• Pinoargote, G., Flores, G., Cooper, K., & Ravishankar, S. (2018). Effects on survival and bacterial community composition of the aquaculture water and gastrointestinal tract of shrimp (Litopenaeus vannamei) exposed to probiotic treatments after an induced infection of acute hepatopancreatic necrosis disease.. Aquaculture Research, 1-19.
• Ravishankar, S., & Pinoargote, G. (2018). Evaluation of the Efficacy of Probiotics in vitro Against Vibrio parahaemolyticus, Causative Agent of Acute Hepatopancreatic Necrosis Disease in Shrimp. . Journal of Probiotics & Health, 6(1), 193. doi:10.4172/2329-8901.1000193
• Jaroni, D., Kakani, R., Ravishankar, S., & Jadeja, R. (2017). Efficacy of roselle (Hibiscus sabdariffa) calyx formulations against Escherichia coli O157:H7 during flume washing of organic leafy greens. Quality Assurance and Safety of Crops & Foods, 9(1), 115-121.
• Joshi, K., Sparks, P., Friedman, M., & Ravishankar, S. (2016). Impact of Plant-Based Antimicrobial Washes on Sensory Properties of Organic Leafy Greens.. Food and Nutrition Sciences, 7, 906-919.
• Litt, P., Ravishankar, S., & Jaroni, D. (2016). Use of Fulvic Acid Formulations as Flume-wash Treatments for Reduction of Escherichia coli O157:H7 on Organic Leafy Greens.. Food Protection Trends, 36(4), 284-292.
• Rada, X., Todd, J. L., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. (2016). Combining essential oils and olive extract for control of multi-drug resistant Salmonella enterica on organic leafy greens.. SDRP Journal of Food Science & Technology, 1(2), 1-9.
• Zhu, L., & Ravishankar, S. (2016). Efficacy of a Citric Acid-based Organic Sanitizer against Salmonella enterica and Background Microflora on Fresh-cut Celery and Leeks.. SDRP Journal of Food Science & Technology, 1(1), 1-7.
• Dev Kumar, G., Crosby, K., Leskovar, D., Bang, H., Jayaprakasha, G., Patil, B., & Ravishankar, S. (2015). A Surveillance of Cantaloupe Genotypes for the Prevalence of Listeria and Salmonella.. Agriculture, Food and Analytical Bacteriology, 5(2), 73-84.
• Ravishankar, S., Denton, J., Friedman, M., & Jaroni, D. (2015). Efficacy of Plant-derived Compounds against Escherichia coli O157:H7 during Flume-washing and Storage of Organic Leafy Greens. Journal of Food Processing and Preservation, 39(6), 2728–2737.
• Zhu, L., Juneja, V., Fonseca, J., & Ravishankar, S. (2015). Survival of Escherichia coli O157:H7 on lettuce harvested from fields irrigated by different irrigation systems and stored under different conditions. Journal of Agriculture and Life Sciences, 2(1), 7-14.
• Buddhini, P. K., Jones, D., Ravishankar, S., & Jaroni, D. (2014). Evaluating the Efficacy of Olive, Apple and Grape Seed Extracts in Reducing Escherichia coli O157:H7 Contamination on Organic Leafy Greens during the Wash Process.. International Journal of Food Science, Nutrition and Dietetics, 3(10), 1-7.
• Zhu, L., Chirase, N., & Ravishankar, S. (2014). Use of Fulvic Acid or Sodium Silicate-Based Sanitizers to Inactivate Listeria monocytogenes, Salmonella Typhimurium and Pseudomonas aeruginosa on Food Contact Surfaces. Journal of Food Safety.
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  Abstract: The objective of this study was to determine the efficacy of five fulvic acid-based and one sodium silicate-based sanitizers against Listeria monocytogenes, SalmonellaTyphimurium DT104 and Pseudomonas aeruginosa on food contact surfaces. Minimum inhibitory concentration assays were conducted to determine the lowest effective concentration of sanitizers A, B, C, D, E and F against each bacterium. Stainless steel, high-density polyethylene, polyvinyl chloride and polycarbonate coupons were inoculated with the culture of one of the test organisms and dried for 1h. The coupons were then sprayed with sanitizer A, B, C, E or F, and treated for 2min. Samples were taken to enumerate the surviving organisms. The sanitizers reduced L.monocytogenes, S. Typhimurium and P.aeruginosa population by 2-6, 2.7-5.8 and 2-6log cfu/coupon on food contact surfaces, respectively. In general, the tested sanitizers were the most effective on P.aeruginosa, followed by S. Typhimurium and then L.monocytogenes. © 2014 Wiley Periodicals, Inc.
• Zhu, L., Olsen, C., Mchugh, T., Friedman, M., Jaroni, D., & Ravishankar, S. (2014). Apple, carrot, and hibiscus edible films containing the plant antimicrobials carvacrol and cinnamaldehyde inactivate Salmonella Newport on organic leafy greens in sealed plastic bags. Journal of Food Science, 79(1), M61-M66.
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  Abstract: The objective of this study was to investigate the antimicrobial effects of carvacrol and cinnamaldehyde incorporated into apple, carrot, and hibiscus-based edible films against Salmonella Newport in bagged organic leafy greens. The leafy greens tested included organic Romaine and Iceberg lettuce, and mature and baby spinach. Each leafy green sample was washed, dip inoculated with S. Newport (107 CFU/mL), and dried. Each sample was put into a Ziploc® bag. Edible films pieces were put into the Ziploc bag and mixed well. The bags were sealed and stored at 4 °C. Samples were taken at days 0, 3, and 7 for enumeration of survivors. On all leafy greens, 3% carvacrol films showed the best bactericidal effects against Salmonella. All 3 types of 3% carvacrol films reduced the Salmonella population by 5 log10 CFU/g at day 0 and 1.5% carvacrol films reduced Salmonella by 1 to 4 log10 CFU/g at day 7. The films with 3% cinnamaldehyde showed 0.5 to 3 log reductions on different leafy greens at day 7. The films with 0.5% and 1.5% cinnamaldehyde and 0.5% carvacrol also showed varied reductions on different types of leafy greens. Edible films were the most effective against Salmonella on Iceberg lettuce. This study demonstrates the potential of edible films incorporated with carvacrol and cinnamaldehyde to inactivate S. Newport on organic leafy greens. Practical Application: Antimicrobial edible films made from apples, carrots, and hibiscus calyces can be used by the food industry to inactivate Salmonella in bagged organic leafy green salads. This study provides a scientific basis for large-scale application of edible fruit- and vegetable-based antimicrobial films on foods to improve microbial food safety. © 2013 Institute of Food Technologists®.
• Chen, C. H., Ravishankar, S., Marchello, J., & Friedman, M. (2013). Antimicrobial activity of plant compounds against Salmonella Typhimurium DT104 in ground pork and the influence of heat and storage on the antimicrobial activity. Journal of food protection, 76(7).
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  Salmonella enterica is a predominant foodborne pathogen that causes diarrheal illness worldwide. A potential method of inhibiting pathogenic bacterial growth in meat is through the introduction of plant-derived antimicrobials. The objectives of this study were to investigate the influence of heat (70°C for 5 min) and subsequent cold storage (4°C up to 7 days) on the effectiveness of oregano and cinnamon essential oils and powdered olive and apple extracts against Salmonella enterica serovar Typhimurium DT104 in ground pork and to evaluate the activity of the most effective antimicrobials (cinnamon oil and olive extract) at higher concentrations in heated ground pork. The surviving Salmonella populations in two groups (heated and unheated) of antimicrobial-treated pork were compared. Higher concentrations of the most effective compounds were then tested (cinnamon oil at 0.5 to 1.0% and olive extract at 3, 4, and 5%) against Salmonella Typhimurium in heated ground pork. Samples were stored at 4°C and taken on days 0, 3, 5, and 7 for enumeration of survivors. The heating process did not affect the activity of antimicrobials. Significant 1.3- and 3-log reductions were observed with 1.0% cinnamon oil and 5% olive extract, respectively, on day 7. The minimum concentration required to achieve . 1-log reduction in Salmonella population was 0.8% cinnamon oil or 4% olive extract. The results demonstrate the effectiveness of these antimicrobials against multidrug-resistant Salmonella Typhimurium in ground pork and their stability during heating and cold storage. The most active formulations have the potential to enhance the microbial safety of ground pork.
• Macarisin, D., Patel, J., Bauchan, G., Giron, J. A., & Ravishankar, S. (2013). Effect of spinach cultivar and bacterial adherence factors on survival of escherichia coli o157:H7 on spinach leaves. Journal of Food Protection, 76(11), 1829-1837.
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  PMID: 24215684;Abstract: Similar to phytopathogens, human bacterial pathogens have been shown to colonize the plant phylloplane. In addition to environmental factors, such as temperature, UV, relative humidity, etc., the plant cultivar and, specifically, the leaf blade morphological characteristics may affect the persistence of enteropathogens on leafy greens. This study was conducted to evaluate the effect of cultivar-dependent leaf topography and the role of strain phenotypic characteristics on Escherichia coli O157:H7 persistence on organic spinach. Spinach cultivars Emilia, Lazio, Space, and Waitiki were experimentally inoculated with the foodborne E. Coli O157:H7 isolate EDL933 and its isogenic mutants deficient in cellulose, curli, or both curli and cellulose production. Leaves of 6-week-old plants were inoculated with 6.5 log CFU per leaf in a biosafety level 2 growth chamber. At 0, 1, 7, and 14 days, E. Coli O157:H7 populations were determined by plating on selective medium and verified by laser scanning confocal microscopy. Leaf morphology (blade roughness and stoma density) was evaluated by low-temperature and variable-pressure scanning electron microscopy. E. Coli O157:H7 persistence on spinach was significantly affected by cultivar and strain phenotypic characteristics, specifically, the expression of curli. Leaf blade roughness and stoma density influenced the persistence of E. Coli O157:H7 on spinach. Cultivar Waitiki, which had the greatest leaf roughness, supported significantly higher E. Coli O157:H7 populations than the other cultivars. These two morphological characteristics of spinach cultivars should be taken into consideration in developing intervention strategies to enhance the microbial safety of leafy greens.
• Macarisin, D., Patel, J., Bauchan, G., Giron, J., & Ravishankar, S. -. (2013). Effect of spinach cultivar and bacterial adherence factors on survival of Escherichia coli O157:H7 on spinach leaves.. Journal of Food Protection, 76(11), 1829-1837.
• Moore-Neibel, K., Gerber, C., Patel, J., Friedman, M., Jaroni, D., & Ravishankar, S. (2013). Antimicrobial activity of oregano oil against antibiotic-resistant Salmonella enterica on organic leafy greens at varyiing exposure times and storage temperatures. Food Microbiology, 34, 123-129.
• Moore-Neibel, K., Gerber, C., Patel, J., Friedman, M., Jaroni, D., & Ravishankar, S. (2013). Antimicrobial activity of oregano oil against antibiotic-resistant Salmonella enterica on organic leafy greens at varying exposure times and storage temperatures. Food Microbiology, 34(1), 123-129.
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  PMID: 23498188;Abstract: The objective of this study was to evaluate the effectiveness of oregano oil on four organic leafy greens (Iceberg and Romaine lettuces and mature and baby spinaches) inoculated with Salmonella Newport as a function of treatment exposure times as well as storage temperatures. Leaf samples were washed, dip inoculated with S. Newport (6-log CFU/ml) and dried. Oregano oil was prepared at 0.1, 0.3, and 0.5% concentrations in sterile phosphate buffered saline (PBS). Inoculated leaves were immersed in the treatment solution for 1 or 2 min, and individually incubated at 4 or 8 °C. Samples were taken at day 0, 1, and 3 for enumeration of survivors. The results showed that oregano oil was effective against S. Newport at all concentrations. S. Newport showed reductions from the PBS control of 0.7-4.8 log CFU/g (Romaine lettuce), 0.8-4.8 log CFU/g (Iceberg lettuce), 0.8-4.9 log CFU/g (mature spinach), and 0.5-4.7 log CFU/g (baby spinach), respectively. The antibacterial activity also increased with exposure time. Leaf samples treated for 2 min generally showed greater reductions (by 1.4-3.2 log CFU/g), than those samples treated for 1 min; however, there was minimal difference in antimicrobial activity among samples stored under refrigeration and abuse temperatures. This study demonstrates the potential of oregano oil to inactivate S. Newport on organic leafy greens. © 2012 Elsevier Ltd.
• Rounds, L., Havens, C. M., Feinstein, Y., Friedman, M., & Ravishankar, S. (2013). Concentration-dependent inhibition of Escherichia coli O157: H7 and heterocyclic amines in heated ground beef patties by apple and olive extracts, onion powder and clove bud oil. Meat Science, 94(4), 461-467.
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  PMID: 23624435;Abstract: The effects of plant compounds on Escherichia coli O157:H7 and two major heat-induced heterocyclic amines (HCAs) MeIQx and PhIP in grilled ground beef patties were determined. Ground beef with added apple and olive extracts, onion powder, and clove bud oil was inoculated with E. coli O157:H7 (107CFU/g) and cooked to reach 45°C at the geometric center, flipped and then cooked for another 5min. Cooled samples were taken for microbiological and HCA analyses. Olive extract at 3% reduced E. coli O157:H7 to below detection. Reductions of up to 1 log were achieved with apple extract. Olive and apple extracts reduced MeIQx by up to 49.1 and 50.9% and PhIP by up to 50.6 and 65.2%, respectively. Onion powder reduced MeIQx and PhIP by 47 and 80.7%, respectively. Inactivation of E. coli O157:H7 and suppression of HCAs in grilled meat were achieved by optimized amounts of selected plant compounds. © 2013 Elsevier Ltd.
• Rounds, L., Havens, C. M., Feinstein, Y., Friedman, M., & Ravishankar, S. (2013). Concentration-dependent inhibition of Escherichia coli O157:H7 and heterocyclic amines in heated ground beef patties by apple and olive extracts, onion powder and clove bud oil. Meat science, 94(4).
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  The effects of plant compounds on Escherichia coli O157:H7 and two major heat-induced heterocyclic amines (HCAs) MeIQx and PhIP in grilled ground beef patties were determined. Ground beef with added apple and olive extracts, onion powder, and clove bud oil was inoculated with E. coli O157:H7 (10⁷ CFU/g) and cooked to reach 45 °C at the geometric center, flipped and then cooked for another 5 min. Cooled samples were taken for microbiological and HCA analyses. Olive extract at 3% reduced E. coli O157:H7 to below detection. Reductions of up to 1 log were achieved with apple extract. Olive and apple extracts reduced MeIQx by up to 49.1 and 50.9% and PhIP by up to 50.6 and 65.2%, respectively. Onion powder reduced MeIQx and PhIP by 47 and 80.7%, respectively. Inactivation of E. coli O157:H7 and suppression of HCAs in grilled meat were achieved by optimized amounts of selected plant compounds.
• Todd, J., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. (2013). The antimicrobial effects of cinnamon leaf oil against multi-drug resistant Salmonella Newport on organic leafy greens. International Journal of Food Microbiology, 166(1), 193-199.
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  PMID: 23911760;Abstract: There is generally no kill-step when preparing salad vegetables, so there is a greater risk for foodborne illness from contaminated vegetables. Some essential oils have antimicrobial activities and could provide a natural way to reduce pathogens on fresh produce. The objective of this study was to investigate the antimicrobial activity of cinnamon oil wash against Salmonella enterica serotype Newport on organic leafy greens. Organic romaine and iceberg lettuce, and organic baby and mature spinach were inoculated with Salmonella Newport and then dip treated in a phosphate buffered saline (PBS) control and 3 different concentrations (0.1, 0.3, and 0.5% v/v) of cinnamon oil. The treatment time varied at either 1 or 2. min, and storage temperature varied at either 4 or 8. °C. Samples were collected at days 0, 1, and 3. For romaine and iceberg lettuce, S. Newport was not recovered on day 3 for 2. min 0.3% and 0.5% cinnamon oil treatments. For mature spinach, S. Newport was not recovered by day 3 for the 2. min 0.3% and 0.5% 4. °C treatments. For baby spinach, there was no recovery of S. Newport by day 1 for all 0.5% treatments. Overall, the cinnamon oil treatments were concentration and time dependent with higher concentrations and longer treatment times providing the greatest reduction in S. Newport population on leafy greens. In addition, the treatments had a residual effect with the greatest reduction generally seen on the last day of sampling. Storage temperature did not have a significant effect on the reduction of S. Newport. Based on the results of this study, cinnamon oil has the potential to be used as a treatment option for washing organic baby and mature spinach, and iceberg and romaine lettuces. © 2013 Elsevier B.V.
• Todd, J., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. (2013). The antimicrobial effects of cinnamon leaf oil against multi-drug resistant Salmonella Newport on organic leafy greens. International journal of food microbiology, 166(1).
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  There is generally no kill-step when preparing salad vegetables, so there is a greater risk for foodborne illness from contaminated vegetables. Some essential oils have antimicrobial activities and could provide a natural way to reduce pathogens on fresh produce. The objective of this study was to investigate the antimicrobial activity of cinnamon oil wash against Salmonella enterica serotype Newport on organic leafy greens. Organic romaine and iceberg lettuce, and organic baby and mature spinach were inoculated with Salmonella Newport and then dip treated in a phosphate buffered saline (PBS) control and 3 different concentrations (0.1, 0.3, and 0.5% v/v) of cinnamon oil. The treatment time varied at either 1 or 2min, and storage temperature varied at either 4 or 8°C. Samples were collected at days 0, 1, and 3. For romaine and iceberg lettuce, S. Newport was not recovered on day 3 for 2min 0.3% and 0.5% cinnamon oil treatments. For mature spinach, S. Newport was not recovered by day 3 for the 2min 0.3% and 0.5% 4°C treatments. For baby spinach, there was no recovery of S. Newport by day 1 for all 0.5% treatments. Overall, the cinnamon oil treatments were concentration and time dependent with higher concentrations and longer treatment times providing the greatest reduction in S. Newport population on leafy greens. In addition, the treatments had a residual effect with the greatest reduction generally seen on the last day of sampling. Storage temperature did not have a significant effect on the reduction of S. Newport. Based on the results of this study, cinnamon oil has the potential to be used as a treatment option for washing organic baby and mature spinach, and iceberg and romaine lettuces.
• Yossa, N., Patel, J., Millner, P., Ravishankar, S., & Lo, Y. M. (2013). Antimicrobial activity of plant essential oils against Escherichia coli O157:H7 and Salmonella on lettuce. Foodborne Pathogens and Disease, 10(1), 87-96.
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  PMID: 23256843;Abstract: Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce pieces were inoculated with a five-strain cocktail of Escherichia coli O157:H7 or Salmonella enterica (5 log CFU/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or Sporan® (800 and 1000 ppm) alone or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and stored at 4 C. Samples were taken to determine the surviving populations of E. coli O157:H7, Salmonella, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds during the 14-day storage period. The effect of treatments on lettuce color and texture was also determined. Cinnamaldehyde-Tween (800 ppm, 800T) reduced E. coli O157:H7 by 2.89 log CFU/g (p
• Yossa, N., Patel, J., Millner, P., Ravishankar, S., & Lo, Y. M. (2013). Antimicrobial activity of plant essential oils against Escherichia coli O157:H7 and Salmonella on lettuce. Foodborne pathogens and disease, 10(1).
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  Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce pieces were inoculated with a five-strain cocktail of Escherichia coli O157:H7 or Salmonella enterica (5 log CFU/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or Sporan(®) (800 and 1000 ppm) alone or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and stored at 4°C. Samples were taken to determine the surviving populations of E. coli O157:H7, Salmonella, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds during the 14-day storage period. The effect of treatments on lettuce color and texture was also determined. Cinnamaldehyde-Tween (800 ppm, 800T) reduced E. coli O157:H7 by 2.89 log CFU/g (p
• Jaroni, D., & Ravishankar, S. (2012). Bactericidal effects of roselle (Hibiscus sabdariffa) against foodborne pathogens in vitro and on romaine lettuce and alfalfa sprouts. Quality Assurance and Safety of Crops & Foods, 4, 33-40.
• Jaroni, D., & Ravishankar, S. (2012). Bactericidal effects of roselle (Hibiscus sabdariffa) against foodborne pathogens in vitro and on romaine lettuce and alfalfa sprouts. Quality Assurance and Safety of Crops and Foods, 4(1), 33-40.
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  Abstract: Introduction: An increased fresh-produce consumption trend accompanied by increased associated outbreaks suggests a need for better intervention strategies. Limitations of chemical sanitizers have necessitated alternative strategies. Research on antimicrobial properties of roselle against food pathogens is limited. Objectives: The study aims to investigate Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes survival in roselle calyx aqueous (RCA) or roselle leaf aqueous (RLA) extracts over 72h at 4, 8 and 25°C; bactericidal effects of roselle calyx concentrate (RCC) and roselle tea (RT) against E.coli O157:H7 on lettuce and of RCC against Salmonella on alfalfa sprouts. Methods: Microbiological analyses and preparation of RCA, RLA, RCC and RT were done according to standard and established methods. Results: No E.coli O157:H7 and Salmonella survivors were detected in RCA or RLA at 24h and all temperatures. L.monocytogenes population was reduced by 5 and 3 logs in RCA and RLA, respectively, at 24h and all temperatures; by 4-6 logs at 4°C and 8°C and to undetectable levels at 25°C, at 48h. At 24h, E.coli O157:H7 and Salmonella were not detected on RCC- or RT-treated lettuce or sprouts. Conclusion: These observations suggest the application of roselle extracts as potential antimicrobials in foods. © 2011 Blackwell Publishing Ltd.
• Moore, K., Gerber, C., Patel, J., Friedman, M., & Ravishankar, S. (2012). Antimicrobial activity of lemongrass oil against Salmonella enterica on organic leafy greens. Journal of Appl. Microbiol, 112, 485-492.
• Moore-Neibel, K., Gerber, C., Patel, J., Friedman, M., & Ravishankar, S. (2012). Antimicrobial activity of lemongrass oil against Salmonella enterica on organic leafy greens. Journal of Applied Microbiology, 112(3), 485-492.
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  PMID: 22188296;Abstract: Aims: We investigated the antimicrobial effectiveness of lemongrass essential oil on organic leafy greens, romaine and iceberg lettuces and mature and baby spinach, inoculated with Salmonella Newport. The influences of exposure times and abuse temperatures on bacterial survival were also investigated. Methods and Results: Leaf samples were washed, inoculated with Salm. Newport (6-log CFUml -1) and dried. Inoculated leaves were immersed in solutions containing 0·1, 0·3 or 0·5% lemongrass oil in phosphate-buffered saline for 1 or 2min and then individually incubated at 4 or 8°C. Samples were taken at day 0, 1 and 3 for the enumeration of survivors. Compared to the PBS control, romaine and iceberg lettuces, and mature and baby spinach samples showed between 0·6-1·5-log, 0·5-4·3-log, 0·5-2·5-log and 0·5-2·2-logCFUg -1 reductions in Salm. Newport by day 3, respectively. Conclusions: The antimicrobial activity of lemongrass oil against Salm. Newport was concentration and time dependent. The antimicrobial activity increased with exposure time; iceberg samples treated for 2min generally showed greater reductions (P
• Ravishankar, S., Jaroni, D., Zhu, L., Olsen, C., McHugh, T., & Friedman, M. (2012). Inactivation of Listeria monocytogenes on Ham and Bologna Using Pectin-Based Apple, Carrot, and Hibiscus Edible Films Containing Carvacrol and Cinnamaldehyde. Journal of Food Science, 77(7), M377-M382.
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  PMID: 22671718;Abstract: Edible films can be used as wrapping material on food products to reduce surface contamination. The incorporation of antimicrobials into edible films could serve as an additional barrier against pathogenic and spoilage microorganisms that contaminate food surfaces. The objective of this study was to investigate the antimicrobial effects of carvacrol and cinnamaldehyde, incorporated into apple, carrot, and hibiscus-based edible films against Listeria monocytogenes on contaminated ham and bologna. Ham or bologna samples were inoculated with L. monocytogenes and dried for 30 min, then surface wrapped with edible films containing the antimicrobials at various concentrations. The inoculated, film-wrapped samples were stored at 4 °C. Samples were taken at day 0, 3, and 7 for enumeration of surviving L. monocytogenes by plating on appropriate media. Carvacrol films showed better antimicrobial activity than cinnamaldehyde films. Compared to control films without antimicrobials, films with 3% carvacrol induced 1 to 3, 2 to 3, and 2 to 3 log CFU/g reductions on ham and bologna at day 0, 3, and 7, respectively. Corresponding reductions with 1.5% carvacrol were 0.5 to 1, 1 to 1.5, and 1 to 2 logs, respectively. At day 7, films with 3% cinnamaldehyde reduced L. monocytogenes population by 0.5 to 1.5 and 0.5 to 1.0 logs on ham and bologna, respectively. Inactivation by apple films was greater than that by carrot or hibiscus films. Apple films containing 3% carvacrol reduced L. monocytogenes population on ham by 3 logs CFU/g on day 0 which was 1 to 2 logs greater than that by carrot and hibiscus films. Films were more effective on ham than on bologna. The food industry and consumers could use these films to control surface contamination by pathogenic microorganisms. © 2012 Institute of Food Technologists ®.
• Ravishankar, S., Jaroni, D., Zhu, L., Olsen, C., McHugh, T., & Friedman, M. (2012). Inactivation of Listeria monocytogenes on Ham and Bologna Using Pectin-Based Apple, Carrot, and Hibiscus Edible Films Containing Carvacrol and Cinnamaldehyde. Journal of Food Science, 77, M377-M382.
• Rounds, L., Havens, C. M., Feinstein, Y., Friedman, M., & Ravishankar, S. (2012). Plant extracts, spices, and essential oils inactivate Escherichia coli O157:H7 and reduce formation of potentially carcinogenic heterocyclic amines in cooked beef patties. Journal of Agricultural and Food Chemistry, 60(14), 3792-3799.
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  PMID: 22397498;Abstract: Meats need to be heated to inactivate foodborne pathogens such as Escherichia coli O157:H7. High-temperature treatment used to prepare well-done meats increases the formation of carcinogenic heterocyclic amines (HCAs). We evaluated the ability of plant extracts, spices, and essential oils to simultaneously inactivate E. coli O157:H7 and suppress HCA formation in heated hamburger patties. Ground beef with added antimicrobials was inoculated with E. coli O157:H7 (10 7 CFU/g). Patties were cooked to reach 45 °C at the geometric center, flipped, and cooked for 5 min. Samples were then taken for microbiological and mass spectrometry analysis of HCAs. Some compounds were inhibitory only against E. coli or HCA formation, while some others inhibited both. Addition of 5% olive or apple skin extracts reduced E. coli O157:H7 populations to below the detection limit and by 1.6 log CFU/g, respectively. Similarly, 1% lemongrass oil reduced E. coli O157:H7 to below detection limits, while clove bud oil reduced the pathogen by 1.6 log CFU/g. The major heterocyclic amines 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were concurrently reduced with the addition of olive extract by 79.5% and 84.3% and with apple extract by 76.1% and 82.1%, respectively. Similar results were observed with clove bud oil: MeIQx and PhIP were reduced by 35% and 52.1%, respectively. Addition of onion powder decreased formation of PhIP by 94.3%. These results suggest that edible natural plant compounds have the potential to prevent foodborne infections as well as carcinogenesis in humans consuming heat-processed meat products. © 2012 American Chemical Society.
• Rounds, L., Havens, C., Feinstein, Y., Friedman, M., & Ravishankar, S. (2012). Plant Extracts, Spices, and Essential Oils Inactivate Escherichia coli O157:H7 and Reduce Formation of Potentially Carcinogenic Heterocyclic Amines in Cooked Beef Patties. J. Agric. Food Chem, 60, 3792-3799.
• Zhu, L., Elguindi, J., Rensing, C., & Ravishankar, S. (2012). Antimicrobial activity of different copper alloy surfaces against copper resistant and sensitive Salmonella enterica. Food Microbiology, 30(1), 303-310.
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  PMID: 22265316;Abstract: Copper has shown antibacterial effects against foodborne pathogens. The objective of this study was to evaluate the antibacterial activity of copper surfaces on copper resistant and sensitive strains of Salmonella enterica. Six different copper alloy coupons (60-99.9% copper) were tested along with stainless steel as the control. The coupons were surface inoculated with either S. Enteritidis or one of the 3 copper resistant strains, S. Typhimurium S9, S19 and S20; stored under various incubation conditions at room temperature; and sampled at various times up to 2h. The results showed that under dry incubation conditions, Salmonella only survived 10-15min on high copper content alloys. Salmonella on low copper content alloys showed 3-4 log reductions. Under moist incubation conditions, no survivors were detected after 30min-2h on high copper content alloys, while the cell counts decreased 2-4 logs on low copper content coupons. Although the copper resistant strains survived better than S. Enteritidis, they were either completely inactivated or survival was decreased. Copper coupons showed better antimicrobial efficacy in the absence of organic compounds. These results clearly show the antibacterial effects of copper and its potential as an alternative to stainless steel for selected food contact surfaces. © 2011 Elsevier Ltd.
• Zhu, L., Elguindy, E., Rensing, C., & Ravishankar, S. (2012). Antimicrobial activity of different copper alloy surfaces against copper resistant and sensitive Salmonella enterica. Food Microbiol, 30, 303-310.
• Zhu, L., Stewart, D., Reineke, K., Ravishankar, S., Palumbo, S., Cirigliano, M., & Tortorello, M. (2012). Comparison of swab transport media for recovery of Listeria monocytogenes from environmental samples. Journal of Food Protection, 75(3), 580-584.
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  PMID: 22410235;Abstract: Environmental monitoring is recognized as an important strategy for controlling Listeria monocytogenes in food processing facilities. Samples are taken by swabbing environmental surfaces, and the swabs are immersed in a medium for transport to the laboratory. In this study, buffered peptone water (BPW), Dey-Engley neutralizing broth (DE), neutralizing buffer (NB), Letheen broth (LE), and newly described MCC buffer (MCC) were evaluated as transport media for recovery of sanitizer-stressed L. monocytogenes from inoculated swabs. After storage at 4°C, the media performed similarly, but at 25°C relative recovery efficiency from the inoculated sponges was DE > LE > BPW > MCC > NB. Recoveries from stainless steel surfaces followed similar trends. MCC, DE, and NB were compared for L. monocytogenes recovery in the presence of Escherichia coli, Enterococcus faecalis, Lactobacillus plantarum, Pseudomonas fluorescens, and Listeria innocua. After 4°C storage, all population levels changed little; after 25°C storage, DE allowed the best growth of L. monocytogenes regardless of other species present. MCC, DE, and NB performed similarly for recovery of L. monocytogenes from an artificial milk biofilm and for recovery of Listeria spp. from swabs obtained from a meat processing facility. Transport medium formulation, time and temperature of swab storage, and coexistence of other species affect recovery of sanitizer-stressed L. monocytogenes from environmental swabs. The study confirms the need to maintain 4°C storage conditions during swab transport. Copyright © International Association for Food Protection.
• Zhu, L., Stewart, D., Reineke, K., Ravishankar, S., Palumbo, S., Cirigliano, M., & Tortorello, M. (2012). Comparison of swab transport media for recovery of Listeria monocytogenes from environmental samples. Journal of Food Protection, 75, 580-584.
• Grosulescu, C., Juneja, V. K., & Ravishankar, S. (2011). Effects and interactions of sodium lactate, sodium diacetate, and pediocin on the thermal inactivation of starved Listeria monocytogenes on bologna. Food Microbiology, 28(3), 440-446.
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  PMID: 21356449;Abstract: The effects and interactions of temperature (56.3-60 °C), sodium lactate (SL; 0-4.8%), sodium diacetate (SDA; 0-2.5%), and pediocin (0-10,000 AU) on starved Listeria monocytogenes (107 CFU/g) on bologna were investigated. Bologna slices containing SL and SDA in the formulation were dipped in pediocin, surface inoculated, and treated at various temperatures using combinations of parameters determined by central composite design. D-values were calculated. The observed D-values ranged from 2.8 min at 60 °C to 24.61 min at 56.3 °C. Injury ranged from 9.1 to 76% under various conditions. The observed D-values were analyzed using second order response surface regression for temperature, SL, SDA, and pediocin, and a predictive model was developed. Predicted D-values were calculated and ranged from 3.7 to 19 min for various combinations of parameters. Temperature alone reduced the predicted D-values from 33.96 min at 56.3 °C to 11.51 min at 60 °C. Addition of SL showed a protective effect. Other combination treatments either reduced or increased D-values depending on temperature. The combination of SL and SDA was effective at lower temperatures, however, higher levels of SDA at higher temperatures made the organism more heat resistant. Pediocin (up to 5000 AU) with increasing temperature and SDA reduced D-values. Depending on temperature and concentration, the interactions between various additives can affect thermal inactivation of L. monocytogenes on bologna. Starvation rendered L. monocytogenes more susceptible to heat and additives. © 2010 Elsevier Ltd.
• Mild, R., Joens, L., Friedman, M., Olsen, C., McHugh, T., Law, B., & Ravishankar, S. (2011). Antimicrobial edible apple films inactivate antibiotic resistant Campylobacter jejuni strains on poultry. Journal of Food Science, 76, M163-M168.
• Moore, K. L., Patel, J., Jaroni, D., Friedman, M., & Ravishankar, S. (2011). Antimicrobial activity of apple, hibiscus, olive, and hydrogen peroxide formulations against Salmonella enterica on organic leafy greens. Journal of Food Protection, 74(10), 1676-1683.
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  PMID: 22004815;Abstract: Salmonella enterica is one of the most common bacterial pathogens implicated in foodborne outbreaks involving fresh produce in the last decade. In an effort to discover natural antimicrobials for use on fresh produce, the objective of the present study was to evaluate the effectiveness of different antimicrobial plant extract-concentrate formulations on four types of organic leafy greens inoculated with S. enterica serovar Newport. The leafy greens tested included organic romaine and iceberg lettuce, and organic adult and baby spinach. Each leaf sample was washed, dip inoculated with Salmonella Newport (10 6 CFU/ml), and dried. Apple and olive extract formulations were prepared at 1, 3, and 5% concentrations, and hibiscus concentrates were prepared at 10, 20, and 30%. Inoculated leaves were immersed in the treatment solution for 2 min and individually incubated at 4°C. After incubation, samples were taken on days 0, 1, and 3 for enumeration of survivors. Our results showed that the antimicrobial activity was both concentration and time dependent. Olive extract exhibited the greatest antimicrobial activity, resulting in 2-to 3-log CFU/g reductions for each concentration and type of leafy green by day 3. Apple extract showed 1-to 2-log CFU/g reductions by day 3 on various leafy greens. Hibiscus concentrate showed an overall reduction of 1 log CFU/g for all leafy greens. The maximum reduction by hydrogen peroxide (3%) was about 1 log CFU/g. The antimicrobial activity was also tested on the background microflora of organic leafy greens, and reductions ranged from 0 to 2.8 log. This study demonstrates the potential of natural plant extract formulations to inactivate Salmonella Newport on organic leafy greens.
• Moore, K., Patel, J., Jaroni, D., Friedman, M., & Ravishankar, S. (2011). Antimicrobial activity of apple, hibiscus, olive, and hydrogen peroxide formulations against Salmonella enterica on organic leafy greens. Journal of Food Protection, 74, 1676-1683.
• Patel, J., Sharma, M., & Ravishakar, S. (2011). Effect of curli expression and hydrophobicity of Escherichia coli O157:H7 on attachment to fresh produce surfaces. Journal of Applied Microbiology, 110(3), 737-745.
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  PMID: 21205101;Abstract: Aim: To investigate the effect of curli expression on cell hydrophobicity, biofilm formation and attachment to cut and intact fresh produce surfaces. Methods and Results: Five Escherichia coli O157:H7 strains were evaluated for curli expression, hydrophobicity, biofilm formation and attachment to intact and cut fresh produce (cabbage, iceberg lettuce and Romaine lettuce) leaves. Biofilm formation was stronger when E. coli O157:H7 were grown in diluted tryptic soy broth (1:10). In general, strong curli-expressing E. coli O157:H7 strains 4406 and 4407 were more hydrophobic and attached to cabbage and iceberg lettuce surfaces at significantly higher numbers than other weak curli-expressing strains. Overall, E. coli O157:H7 populations attached to cabbage and lettuce (iceberg and Romaine) surfaces were similar (P>0·05), indicating produce surfaces did not affect (P0·05) in most cases. Escherichia coli O157:H7 attachment and attachment strength (SR) to intact and cut produce surfaces increased with time. Conclusions: Curli-producing E. coli O157:H7 strains attach at higher numbers to produce surfaces. Increased attachment of E. coli O157:H7 on cut surfaces emphasizes the need for an effective produce wash to kill E. coli O157:H7 on produce. Significance and Impact of the Study: Understanding the attachment mechanisms of E. coli O157:H7 to produce surfaces will aid in developing new intervention strategies to prevent produce outbreaks. © 2011 The Society for Applied Microbiology. No claim to US Government works.
• Patel, J., Sharma, M., & Ravishankar, S. (2011). Effect of curli expression and hydrophobicity of Escherichia coli O157:H7 on attachment to fresh produce surfaces. J. Appl. Microbiol, 110, 737-745.
• Maks, N., Zhu, L., Juneja, V. K., & Ravishankar, S. (2010). Sodium lactate, sodium diacetate and pediocin: Effects and interactions on the thermal inactivation of Listeria monocytogenes on bologna. Food Microbiology, 27(1), 64-69.
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  PMID: 19913694;Abstract: The effects and interactions of temperature (56.3-60 °C), sodium lactate (SL; 0-4.8%), sodium diacetate (SD; 0-0.25%) and pediocin (0-10,000 AU) on Listeria monocytogenes on bologna were studied and a predictive inactivation model was developed. Bologna was manufactured with different SL/SD concentrations in the formulation, dipped in pediocin solution and treated at different temperatures using combinations of parameters determined by central composite design. D-values were calculated and analyzed using second order response regression. Predicted D-values were also calculated. The observed D-values for L. monocytogenes on bologna ranged from 2.10 to 35.59 min. Temperature alone decreased predicted D-values from 99.02 min at 56.3 °C to 44.71 min at 60.0 °C. Adding SL decreased D-values (85.43-22.71 min) further; however, heat and SD combined was the most effective for reducing L. monocytogenes on bologna. An SD level of 0.25% at 58.2 °C had the overall lowest predicted D-value (15.95 min). Combination treatments increased or decreased D-values, depending on the temperature. Pediocin (2500 and 5000 AU) and heat decreased D-values, but exhibited a protective effect at higher concentrations (≥7500 AU). The results showed that interactions between additives in formulations can vary at different temperatures/concentrations, thereby affecting thermal inactivation of foodborne pathogens in meat products. Hence, food processors should modify food formulations carefully, and verify with adequate testing so that product safety is not compromised. © 2009 Elsevier Ltd.
• Ravishankar, S., Zhu, L., & Jaroni, D. (2010). Assessing the cross contamination and transfer rates of Salmonella enterica from chicken to lettuce under different food-handling scenarios. Food Microbiology, 27(6), 791-794.
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  PMID: 20630321;Abstract: Cross contamination of foodborne pathogens from raw meats to ready-to-eat foods has caused a number of foodborne outbreaks. The cross contamination and transfer rates of Salmonella enterica from chicken to lettuce under various food-handling scenarios were determined. The following scenarios were tested: in scenario 1, cutting board and knife used to cut chicken (106 CFU/g) were also used for cutting lettuce, without washing; in scenario 2, cutting board and knife were washed with water separately after cutting chicken, and subsequently used for cutting lettuce; and in scenario 3, cutting board and knife were thoroughly washed with soap and hot water after cutting chicken, and before cutting lettuce. In each scenario, cutting board, knife, chicken and lettuce were sampled for population of S. enterica. For scenario 1, both before and after cutting lettuce, the cutting board and knife each had about 2 logs CFU/cm2 of S. enterica, respectively. The cut lettuce had about 3 logs CFU/g of S. enterica. In scenario 2, fewer organisms (0.5-2.4 logs CFU/g or cm2) were transferred. The transfer rates in both scenarios ranged from 0.02 to 75%. However, in scenario 3,
• Friedman, M., Zhu, L., Feinstein, Y., & Ravishankar, S. (2009). Carvacrol facilitates heat-induced inactivation of escherichia coli O157: H7 and inhibits formation of heterocyclic amines in grilled ground beef patties. Journal of Agricultural and Food Chemistry, 57(5), 1848-1853.
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  PMID: 19222201;Abstract: Heating meat at high temperature and/or for a long time to kill foodborne pathogens increases the formation of potentially carcinogenic heterocyclic amines. To overcome this problem, 1% carvacrol, the main ingredient of oregano oil widely used in salad dressings, was added to ground beef, which was mixed well and then inoculated with Escherichia coli O157:H7. Beef patties were then prepared and heat-treated on a preheated electrical skillet to reach an internal temperature of 65, 70, or 80 °C at the cold spot. Samples were enumerated for surviving E. coli O157:H7 population by plating on appropriate media. Heterocyclic amines (MeIQ, MeIQx, and PhIP) were extracted from ground beef using solid phase extraction and analyzed by mass spectrometry. Multiple reaction monitoring (MRM) scan type in positive mode was used to monitor the amines of interest. Compared to controls, the population of E. coli O157:H7 was reduced by 2.5-5 logs. The corresponding highest reductions in the three major amines were MeIQ, 58%; MeIQx, 72%; and PhIP, 78%. The results show that carvacrol concurrently reduced E. coli O157:H7 and amines in a widely consumed meat product. Possible mechanisms of the beneficial effects and dietary significance of the results are discussed. © 2009 American Chemical Society.
• Ravishankar, S., Zhu, L., Olsen, C. W., McHugh, T. H., & Friedman, M. (2009). Edible apple film wraps containing plant antimicrobials inactivate foodborne pathogens on meat and poultry products. Journal of Food Science, 74(8), M440-M445.
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  PMID: 19799671;Abstract: ABSTRACT Apple-based edible films containing plant antimicrobials were evaluated for their activity against pathogenic bacteria on meat and poultry products. Salmonella enterica or E. coli O157:H7 (107 CFU/g) cultures were surface inoculated on chicken breasts and Listeria monocytogenes (10 6 CFU/g) on ham. The inoculated products were then wrapped with edible films containing 3 concentrations (0.5%, 1.5%, and 3%) of cinnamaldehyde or carvacrol. Following incubation at either 23 or 4 °C for 72 h, samples were stomached in buffered peptone water, diluted, and plated for enumeration of survivors. The antimicrobial films exhibited concentration-dependent activities against the pathogens tested. At 23 °C on chicken breasts, films with 3% antimicrobials showed the highest reductions (4.3 to 6.8 log CFU/g) of both S. enterica and E. coli O157:H7. Films with 1.5% and 0.5% antimicrobials showed 2.4 to 4.3 and 1.6 to 2.8 log reductions, respectively. At 4 °C, carvacrol exhibited greater activity than did cinnamaldehyde. Films with 3%, 1.5%, and 0.5% carvacrol reduced the bacterial populations by about 3, 1.6 to 3, and 0.8 to 1 logs, respectively. Films with 3% and 1.5% cinnamaldehyde induced 1.2 to 2.8 and 1.2 to 1.3 log reductions, respectively. For L. monocytogenes on ham, carvacrol films induced greater reductions than did cinnamaldehyde films at all concentrations tested. In general, the reduction of L. monocytogenes on ham at 23 °C was greater than at 4 °C. Added antimicrobials had minor effects on physical properties of the films. The results suggest that the food industry and consumers could use these films as wrappings to control surface contamination by foodborne pathogenic microorganisms. © 2009 Institute of Food Technologists®.
• Ravishankar, S., Zhang, H., & Kempkes, M. L. (2008). Pulsed electric fields. Food Science and Technology International, 14(5), 429-432.
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  Abstract: The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular content and transfer of genetic material across cell membrane. The lethal effects of PEF to microorganisms were studied in 1990s when laboratory and pilot plant equipment were developed to evaluate the effect of PEF as a nonthermal food process to provide consumers with microbiologically-safe and fresh-like quality foods. Application of high voltage electric field at a certain level for a very short time by PEF not only inactivates pathogenic and spoilage microorganisms, but also results in the retention of flavor, aroma, nutrients, and color of foods. The first commercial PEF pasteurization of apple cider products took place in 2005 in the United States. This paper provides current information about PEF food processing and identifies a list of research needs to further develop PEF technology for food processing and preservation. © 2008 SAGE Publications.
• Fonseca, J. M., & Ravishankar, S. (2007). Safer salads. American Scientist, 95(6), 494-501.
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  Abstract: People may wonder as to why they get sick after eating fresh fruits and vegetables. This is mainly due to the presence of microorganisms that brings food poisoning and that people are now eating more fresh fruits, vegetables and salads especially in places that are common settings for foodborne illnesses in the likes of restaurants or public gatherings. The risk roots all the way on how the food were prepared and distributed that can easily spread the contamination. On the other hand, most produce are from abroad which may have gone through lesser strict standards. Thus, a discussion is presented regarding on the pathogens on produce, the microbes before and after the harvest, the right sanitizer to be used and some tips for consumers.
• Ravishankar, S., & Maks, N. (2007). Basic Food Microbiology. Advances in Thermal and Non-Thermal Food Preservation, 1-31.
• Pascall, M. A., Ravishankar, S., Ghiron, K., Lee, B. T., & Johannessen, J. N. (2006). Evaluation of magnetic resonance for detection of bacterial contamination in low-acid, shelf-stable packaged soymilk. Journal of Food Protection, 69(7), 1668-1674.
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  PMID: 16865902;Abstract: This study evaluated magnetic resonance (MR) as a nondestructive method for detection of bacterial contamination in shelf-stable soymilk and cheese sauce. To accomplish this, individual 355-ml polymeric trays filled with soymilk and inoculated with Bacillus stearothermophilus and Bacillus subtilis (10 3 CFU) were incubated for up to 28 h at 55°C and 62 h at 37°C. respectively. MR relaxation times (T2) of these samples were then correlated with the bacterial growth as well as viscosity and pH changes caused by the bacteria in the packaged soymilk. In addition, this study investigated the ability of MR to differentiate between regularly processed cheese sauce and cheese sauce that was modified with α-amylase as a spoilage simulation. Results showed increased MR T2 relaxation times after the bacterial populations reached 108 CFU/ml (after 18 h) and 107 CFU/ml (after 44 h) for B. stearothermophilus and B. subtilis, respectively. B. subtilis had an undetectable influence on viscosity but a profound influence on pH. B. stearothermophilus, in comparison, significantly lowered the pH and increased the viscosity of the soymilk. MR was able to distinguish between regularly processed 85-g pouches of cheese sauce and other pouches with sauce that were modified with 0.5 ml of 1% α-amylase solution. These results showed that MR has the potential to be used for nondestructive detection of physical changes in soymilk and cheese sauce induced by bacterial growth and enzymatic activities, respectively. Copyright ©, International Association for Food Protection.
• Schlesser, J. E., Gerdes, R., Ravishankar, S., Madsen, K., Mowbray, J., & Teo, A. Y. (2006). Survival of a five-strain cocktail of Escherichia coli O157:H7 during the 60-day aging period of Cheddar cheese made from unpasteurized milk. Journal of Food Protection, 69(5), 990-998.
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  PMID: 16715794;Abstract: The U.S. Food and Drug Administration Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at ≥2°C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk. The objective of this study was to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk. Cheddar cheese was made from unpasteurized milk inoculated with 101 to 105 CFU/ml of a five-strain cocktail of acid-tolerant Escherichia coli O157:H7. Samples were collected during the cheese manufacturing process. After pressing, the cheese blocks were packaged into plastic bags, vacuum sealed, and aged at 7°C. After 1 week, the cheese blocks were cut into smaller-size uniform pieces and then vacuum sealed in clear plastic pouches. Samples were plated and enumerated for E. coli O157:H7. Populations of E. coli O157:H7 increased during the cheese-making operations. Population of E. coli O157:H7 in cheese aged for 60 and 120 days at 7°C decreased less than 1 and 2 log, respectively. These studies confirm previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Subpasteurization heat-treatment runs were conducted at 148°F (64.4°C) for 17.5 s on milk inoculated with E. coli O157:H7 at 105 CFU/ml. These heat-treatment runs resulted in a 5-log E. coli O157:H7 reduction.
• Uhart, M., Maks, N., & Ravishankar, S. (2006). Effect of spices on growth and survival of Salmonella Typhimurium DT 104 in ground beef stored at 4 and 8C. Journal of Food Safety, 26(2), 115-125.
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  Abstract: Few studies have addressed the use of spices against pathogens associated with meat. The effects of garlic, ginger and turmeric were evaluated against Salmonella Typhimurium DT 104 that were inoculated either in spice paste or in buffered peptone water (BPW) or in heat-treated ground beef and stored at 4 and 8C for 10 days. Data from the spice pastes study showed a decrease in Salmonella Typhimurium DT 104 counts, and the greatest reduction (3.39 log) was observed in garlic paste stored at 4C. Garlic in BPW data showed a reduction of 1.5 and 1.0 log in Salmonella Typhimurium counts at 4 and 8C, respectively. Ground beef stored at 4C showed no growth or a slight reduction in growth in samples with spice, while all samples at 8C showed an increase in Salmonella Typhimurium counts. Results show that the spices inhibit or inactivate Salmonella Typhimurium DT 104 when they are in direct contact. However, when spices are added to a complex food system such as ground beef, the inhibitory activity of these spices considerably decreases. © 2006, The Author(s).
• Gupta, S., & Ravishankar, S. (2005). A comparison of the antimicrobial activity of garlic, ginger, carrot, and turmeric pastes against Escherichia coli O157:H7 in laboratory buffer and ground beef. Foodborne Pathogens and Disease, 2(4), 330-340.
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  PMID: 16366855;Abstract: The antimicrobial effects of garlic, ginger, carrot and turmeric pastes against Escherichia coli O157:H7 in laboratory buffer and model food system were investigated. Turmeric paste, fresh carrot, ginger and garlic pastes from roots, and commercial ginger and garlic paste were heated alone or with buffered peptone water (BPW) or ground beef at 70°C for 7 min. All samples were inoculated with a three strain cocktail of overnight cultures of E. coli O157: H7 and stored at 4°C and 8°C for 2 weeks. Each paste exhibited different antimicrobial effects alone and in ground beef or BPW at 4°C and 8°C for 2 weeks. Commercial ginger paste and fresh garlic paste showed the strongest antimicrobial activity with complete inactivation of E. coli O157:H7 in the paste at 3 days at 4°C and 8°C. Carrot and turmeric pastes did not show any antimicrobial activity both at 4°C and 8°C. Commercial garlic showed antimicrobial activity at both 4°C and 8°C (about 1 log CFU/g reduction) in the paste. However, fresh ginger paste showed antimicrobial activity only at 8°C. Only commercial ginger paste had antimicrobial activity in BPW at 4°C for 2 weeks. However, commercial ginger paste showed antimicrobial activity in ground beef at 3 days and after (about 1-2 log CFU/g) compared to control samples at 8°C for 2 weeks. Fresh garlic paste showed antimicrobial activity only in BPW (1.3 log CFU/g) at 8°C. These results indicate that the antimicrobial activity of these pastes is decreased in ground beef and laboratory buffer. © Mary Ann Liebert, Inc.
• Ravishankar, S., Maks, N. D., Teo, A. Y., Strassheim, H. E., & Pascall, M. A. (2005). Minimum leak size determination, under laboratory and commercial conditions, for bacterial entry into polymeric trays used for shelf-stable food packaging. Journal of Food Protection, 68(11), 2376-2382.
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  PMID: 16300076;Abstract: This study sought to determine the minimum leak size for entry of Enterobacter aerogenes under laboratory conditions, and normal flora under commercial conditions, into tryptic soy broth with yeast extract (TSBYE), homestyle chicken, and beef enchilada packaged in 355-ml polyethylene terephthalate/ethylene vinyl alcohol/polypropylene trays. Channel leaks (diameters of 50 to 200 μm) were made across the sealing area of the trays. Pinholes (diameters of 5 to 50 μm) were made by imbedding laser-drilled metal and plastic disks into the tray lids. For the laboratory simulation, all trays were submerged and agitated for 30 min at 25°C in phosphate-buffered saline that contained 107 CFU/ml of E. aerogenes. Under commercial conditions, trays with channel leaks were processed in retorts to achieve commercial sterility. All trays were subsequently incubated at 37°C for 2 weeks, and their contents plated onto eosin-methylene blue agar (for laboratory simulation) to enumerate E. aerogenes and brain heart infusion agar (for commercial conditions) to determine the presence of any bacteria. Under laboratory conditions, minimum pinhole sizes for E. aerogenes entry approximated 5 μm (TSBYE, metal disks; homestyle chicken, plastic disks), 20 μm (beef, plastic disks), and 30 μm (beef, metal disks). The minimum channel leak sizes for entry of E. aerogenes approximated 10 μm (TSBYE), 70 μm (chicken), and 200 μm (beef enchilada). Under commercial conditions, the minimum channel leak size for bacterial entry approximated 40 μm (TSBYE), 50 μm (homestyle chicken), and more than 200 μm (beef). Results showed that E. aerogenes can enter pinholes as small as 5 μm under a worst-case scenario. This information can be used to set pass and fail parameters for leak detection devices. Copyright ©, International Association for Food Protection.
• Fleischman, G. J., Ravishankar, S., & Balasubramaniam, V. M. (2004). The inactivation of Listeria monocytogenes by pulsed electric field (PEF) treatment in a static chamber. Food Microbiology, 21(1), 91-95.
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  Abstract: An experimental analysis of the effect of pulsed electric field (PEF) energy on the inactivation of Listeria monocytogenes was conducted using a custom-designed static chamber and a gel suspension medium for treatment. This allowed PEF energy to be delivered to the suspension under near isothermal conditions. The effects of variations in the number of pulses (5-50 pulses), electric field strength (15-30 kV/cm), temperature (0-60°C) and media bases (water and skim milk) on the inactivation of L. monocytogenes were examined. At temperatures less than 50°C a maximum of 1 log reduction was obtained for L. monocytogenes regardless of pulse number or electric field strength within the ranges examined. In skim milk no reduction occurred. At 50°C and 55°C synergy between PEF and thermal energy was observed. The experimental approach separated the contribution of PEF and thermal energy to total kill and thus allowed this synergy to be quantified. At 55°C the kill due to PEF energy increased to 4.5 logs with another 4.5 logs reduction attributable to thermal energy. It appears that under the conditions of this study PEF alone has a very limited effect on the reduction of L. monocytogenes. However, the addition of thermal energy not only contributed to the kill, but also increased the susceptibility of L. monocytogenes to PEF energy. Published by Elsevier Science Ltd.
• Tipparaju, S., Ravishankar, S., & Slade, P. J. (2004). Survival of Listeria monocytogenes in Vanilla-Flavored Soy and Dairy Products Stored at 8°C. Journal of Food Protection, 67(2), 378-382.
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  PMID: 14968973;Abstract: The survival of Listeria monocytogenes V37 in vanilla-flavored yogurt (low-fat and nonfat) and soy milk (low-fat and Plus) stored at 8°C for 31 days was investigated. Commercial samples of yogurt and soy milk were used. These samples were inoculated with either 104 or 107 CFU of L. monocytogenes per ml. Sampling was carried out every 3 to 4 days initially and was then carried out weekly, for a total storage time of 31 days. Each time a sample was collected, the pH of the sample was measured. After 31 days, low-fat plain, low-fat vanilla, and nonfat plain yogurt samples inoculated with 104 CFU/ml showed 2.5-log reductions in viable cell populations, and nonfat vanilla yogurt showed a 3.5-log reduction. For yogurt inoculated with 107 CFU/ml, reductions of 2.5 log CFU/ml were observed for plain low-fat and nonfat yogurts, and reductions of 5 log CFU/ ml were observed for vanilla-flavored low-fat and nonfat yogurts. In vanilla-flavored and plain low-fat and Plus soy milk samples, cell counts increased from 104 and 107 CFU/ml to 109 CFU/ ml at 7 and 3 days of storage, respectively, at 8°C. Coagulation in soy milk samples was observed when the cell population reached 109 CFU/ml. In soy milk, the L. monocytogenes population did not change for up to 31 days. Vanillin had an inhibitory effect on L. monocytogenes in yogurt but not in soy milk.
• Uhart, M., Ravishankar, S., & Maks, N. D. (2004). Control of Listeria monocytogenes with combined antimicrobials on beef franks stored at 4°C. Journal of Food Protection, 67(10), 2296-2301.
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  PMID: 15508647;Abstract: Contamination of ready-to-eat meat products such as beef franks with Listeria monocytogenes has become a major concern for the meat processing industry and an important food safety issue. The objective of this study was to determine the effectiveness of combinations of antimicrobials as aqueous dipping solutions to control L. monocytogenes on vacuum-packaged beef franks stored at 4°C for 3 weeks. Commercial beef franks were dipped for 5 min in three antimicrobial solutions: pediocin (6,000 AU), 3% sodium diacetate and 6% sodium lactate combined, and a combination of the three antimicrobials. Samples were then inoculated with 107 CFU/g of either four L. monocytogenes strains individually or a cocktail of the four strains, vacuum packaged, and stored at 4°C for 3 weeks. Sampling was carried out at day 0 and after 2 and 3 weeks of storage. Individual strains, as well as the cocktail, exhibited different responses to the antimicrobial treatments. After 2 and 3 weeks of storage at 4°C, pediocin-treated beef franks showed a less than 1-log reduction for all bacterial strains. Samples treated with the sodium diacetate-sodium lactate combination showed about a 1-log reduction after 2 weeks of storage for all strains and between a 1- and 2-log reduction after 3 weeks of storage, depending on the bacterial strain. When the three antimicrobials were combined, reductions ranged between 1 and 1.5 log units and 1.5 to 2.5 log units after 2 and 3 weeks of storage, respectively, at 4°C. These results indicate that the use of combined antimicrobial solutions for dipping treatments is more effective at inhibiting L. monocytogenes than treatments using antimicrobials such as pediocin separately.
• Ravishankar, S., Fleischman, G. J., & Balasubramaniam, V. M. (2002). The inactivation of Escherichia coli O157:H7 during pulsed electric field (PEF) treatment in a static chamber. Food Microbiology, 19(4), 351-361.
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  Abstract: The inactivation of Escherichia coli O157:H7 by pulsed electric field (PEF) processing as a function of electric field strength (15-30 kV cm-1), pulse number (1-20), temperature (5-65°C) and pH (3.5 and 6.8) was studied using a commercially available pulser, a static chamber and gellan gum gel as a suspension medium. The custom-designed static chamber achieved near-isothermal treatment conditions while eliminating flow field effects. Gellan gum gel was used to suspend the bacteria for treatment. It allowed uniform distribution of bacteria and neither inhibited nor promoted bacterial growth. The combination of equipment design and experimental protocol allowed the contribution of electrical (PEF) and thermal energy to be measured separately. In water-based gel, a maximum of 3 log reductions were achieved by PEF energy. Greater inactivation was observed at a treatment temperature of 55°C, but the additional inactivation was attributable entirely to thermal energy. Microbial injury was also observed at this temperature. At 60°C and above, complete inactivation was achieved, but this was attributable entirely to thermal energy. In water-based gellan gum gel adjusted to pH 3.5, again a 3 log reduction was achieved by PEF. In gel made from freshly squeezed apple juice naturally having the same pH, however, a maximum of 1.5 log reduction was observed.
• Teo, A. Y., Ravishankar, S., & Sizer, C. E. (2001). Effect of low-temperature, high-pressure treatment on the survival of Escherichia coli O157:H7 and Salmonella in unpasteurized fruit juices. Journal of Food Protection, 64(8), 1122-1127.
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  PMID: 11510646;Abstract: The destructive effect of high pressure (615 MPa) combined with low temperature (15°C) on various strains of Escherichia coli O157:H7 and various serovars of Salmonella in grapefruit, orange, apple, and carrot juices was investigated. The three-strain cocktail of E. coli O157:H7 (SEA13B88, ATCC 43895, and 932) was found to be most sensitive in grapefruit juice (8.34-log reduction) and least in apple juice (0.41-log reductions) when pressurized at 615 MPa for 2 min at 15°C. Correspondingly, no injured survivor was detected in grapefruit and carrot juices under similar treatment conditions. No Salmonella spp. were detected in a 2-min pressure treatment (615 MPa, 15°C) of grapefruit and orange fruit juices. Except for Enteritidis, all four serovars tested in the present study have viability loss of between 3.92- and 5.07-log reductions when pressurized in apple juice at 615 MPa for 2 min at 15°C. No injured cells were recovered from grapefruit and orange juices, whereas the same treatment demonstrated reduction in numbers of Salmonella serovars Agona and Muenchen in apple juices and to a lesser extent with Typhimurium, Agona, and Muenchen in carrot juice. The present study demonstrated that low-temperature, high-pressure treatment has the potential to inactivate E. coli O157:H7 strains and different Salmonella spp. in different fruit juices.
• Ravishankar, S., Harrison, M. A., & Wicker, L. (2000). Protein profile changes in acid adapted Listeria monocytogenes exhibiting cross-protection against an activated lactoperoxidase system in tryptic soy broth. Journal of Food Safety, 20(1), 27-42.
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  Abstract: Foodborne pathogens often tolerate and survive environmental stress conditions including extreme acidity to varying degrees. One possible reason for this survival may be the production of protective stress proteins during acid shock (ASR) and/or tolerance (ATR) responses. The ASR and ATR of Listeria monocytogenes strains V7, V37 and CA in tryptic soy broth without dextrose acidified with lactic acid were studied. Possible cross-protection of acid adapted cells against an activated lactoperoxidase system was also determined. The strains were either directly challenged at pH 4.0 and 3.5 to study their ASR or initially adapted at pH 5.5 for the equivalent of 1 generation before challenging at pH 4.0 and 3.5 to study their ATR. Adapted and nonadapted cells were challenged at pH 4.5 with or without an activated lactoperoxidase system. In all cases viability was determined by enumeration over a period of 24 or 48 h after challenge and the production of stress proteins analyzed by 2-dimensional gel electrophoresis. While there were some differences in the survival responses for each strain, the acid adapted cells of each strain survived to a greater degree than nonadapted cells at both pH 4.0 (at least 10 fold at 24 h) and pH 3.5 (at least 1000 fold at 6 h) but not at pH 4.5. The acid adapted cells exposed to the lactoperoxidase system survived better (at least 5-fold) than their nonadapted counterparts for all 3 strains at 24 and 48 h. The 2-dimensional gel analysis for all 3 strains showed that the adapted and nonadapted cells underwent a change in their physiology, (at pH 4.0 compared to the control at pH 7.0; at pH 4.5 with the addition of lactoperoxidase system components) in that there was induction as well as repression of several proteins.
• Ravishankar, S., & Harrison, M. A. (1999). Acid adaptation of Listeria monocytogenes strains does not offer cross-protection against an activated lactoperoxidase system. Journal of Food Protection, 62(6), 670-673.
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  PMID: 10382659;Abstract: Listeria monocytogenes has been implicated in foodborne illness outbreaks involving several types of cheeses made from acidified milk. Acid shock response (ASR) and acid tolerance response (ATR) could be possible reasons for its survival. The ASR and ATR of three strains of L. monocytogenes (V7, V37, and CA) in skim milk acidified to pH 4.0 and 3.5 with lactic acid and held at 32°C were studied. Studies were also done to determine if acid adaptation of the organism enhanced survival in the presence of an activated lactoperoxidase system. The cells were directly shocked at pH 4.0 and 3.5 in skim milk to study the ASR. To study the ATR, cells were initially adapted in skim milk at a mild pH of 5.5 for the equivalent of one generation before being shocked at pH 4.0 and 3.5 in skim milk. Cells adapted at pH 5.5 in tryptic soy broth without dextrose and nonadapted cells were challenged at pH 4.5 in skim milk with or without an activated lactoperoxidase system. In all cases, viability and pH were measured 24 or 48 h after challenge. In pH 4.0 skim milk, for all three strains, the adapted cell population survived better (0.5 to 1.0 log higher) than that of nonadapted cells for 24 h. In pH 3.5 skim milk, the acid-adapted populations of all three strains were 3 to 4 logs greater than those of nonadapted cells at 6 h. The acid adapted cells of all three strains had survival rates similar to those of the nonadapted cells at pH 4.5 both in the presence and absence of an activated lactoperoxidase system. It was also evident that these strains do not exhibit an adaptive ATR at pH 4.5, although they do at lower pH levels (pH 4.0 and 3.5). Survival due to the ATR was better seen at pH 3.5 than at pH 4.0.

Proceedings Publications

• Joshi, K., Ravishankar, S., Nolte, K. D., & Siemens, M. C. (2016, August). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and the efficacy of plant antimicrobials and organic sanitizers. In Annual Meeting of the International Association for Food Protection, No. P1-42, J. of Food Production Supplement A, 79, 96 (abstr)..
• Bevington, R., Nolte, K., & Ravishankar, S. (2014, July). Best Methods to Present Research Information via Video Formats to a Public Audience.. In American Society for Horticultural Science Annual Meeting 2014 Proceedings.
• Nolte, K., & Ravishankar, S. (2014, July). The 5 Year Anniversary of the Arizona Leafy Green Marketing Agreement: What Works and What Doesn’t.. In American Society for Horticultural Science Annual Meeting 2014 Proceedings.
• Wilson, R., Bevington, R., Nolte, K., & Ravishankar, S. (2014, July). Extending Research Impacts to a General Audience Via Video: The Good, The Bad, And The Ugly.. In American Society for Horticultural Science Annual Meeting 2014 Proceedings,.

Presentations

• Bains, K., Rowlands, D., Rao, A., & Ravishankar, S. (2021, October). Biofilms: Significance in Food Processing and Control Strategies.. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Park, R., Rao, A., Rowlands, D., Wei, Q., Porchas, M., Brierley, P., Patil, B., & Ravishankar, S. (2021, October). Why We Peel Melons: A Peek into the Prevalence of Foodborne Pathogens Among Field-Grown Melons in Arizona.. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Ravishankar, S. (2021, April). Symposium Talk ""Attachment Strength of Foodborne Pathogens and Efficacy of Plant-based Antimicrobials Against Salmonella enterica and Listeria monocytogenes on Melons Grown in Different Regions of the United States". Annual Meeting of the American Chemical Society- Symposium "Beyond Chemistry: Consumer Acceptance of Flavor, Food Safety and Health Benefits of Fruits and Vegetables"". Virtual- Zoom: American Chemical Society.
• Ravishankar, S. (2021, February). Research Overview- Food Safety: Creative a Safer Farm to Fork Journey. Graduate Student Orientation 2021- Faculty Datablitz. Virtual- Zoom: ACBS.
• Ravishankar, S. (2021, June). Filling Science-based Knowledge Gaps in Food Safety: Prevalence of Foodborne Pathogens in Fresh Produce Production Environments. Burroughs Wellcome Foundation Meeting. Virtual-Google Meet: Burroughs Wellcome Foundation.
• Ravishankar, S. (2021, November 10). Current Trends in Food Safety & Food Production. International Conference on “Novel Paradigms in Biotechnology-Bioengineering Interface: From Concepts to Reality”. Virtual- Zoom: Sathyabama Institute of Science and Technology, India, Indian Association of Applied Microbiologists, and California University of Science & Medicine.
• Ravishankar, S. (2021, September 27). Scholarly Activities in Life Sciences: Effective Grant writing and Intellectual Property Protection for Innovation and Entrepreneurship. Special Seminar- Center for Drug Discovery & Development, Sathyabama University, Chennai, India. Virtual- Zoom: Sathyabama University.
• Singh, J., Metrani, R., Crosby, K., Jifon, J., Ravishankar, S., & Patil, B. (2021, April). Assessment of carotenoids and sugars contents in melon cultivars harvested from five different locations in the United States. American Chemical Society National Meeting & Exposition. San Antonio, TX: American Chemical Society.
• Singh, J., Metrani, R., Crosby, K., Jifon, J., Ravishankar, S., & Patil, B. (2021, August). A metabolomics profiling of cantaloupe hybrids grown in various locations in the United States. American Chemical Society National Meeting & Exposition. Atlanta, GA: American Chemical Society.
• Singh, J., Metrani, R., Crosby, K., Jifon, J., Ravishankar, S., & Patil, B. (2021, August). Comparative phytochemical profiling of different melon hybrids grown in different locations in the United States. American Society for Horticultural Sciences Annual Conference. Denver, CO: American Society for Horticultural Sciences.
• Zhu, L., Zerzghi, H., Betancourt, W., Gerba, C., Bright, K., Rock, C., & Ravishankar, S. (2021, October). Isolation of Indicator and Foodborne Pathogenic Bacteria from Non-traditional Irrigation Water Sources in Arizona.. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Arellano, S., Law, B., & Ravishankar, S. (2020, October). Green Sanitizers: Improved Safety and Shelf-life of Iceberg Lettuce Washed with Plant-based Antimicrobial Microemulsions. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Arellano, S., Law, B., & Ravishankar, S. (2020, October). Green Sanitizers: Improved Safety and Shelf-life of Iceberg Lettuce Washed with Plant-based Antimicrobial Microemulsions. International Association for Food Protection (IAFP) Annual Conference. Virtual- Zoom: IAFP.
• Oliveras, V., Park, R., & Ravishankar, S. (2020, October). Efficacy of ozone against Salmonella Newport in recycled and non-recycled spinach wash water. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Oliveras, V., Park, R., & Ravishankar, S. (2020, October). Efficacy of ozone against Salmonella Newport in recycled and non-recycled spinach wash water. International Association for Food Protection (IAFP) Annual Conference. Virtual- Zoom: IAFP.
• Park, R., Rowlands, D., Porchas, M., Brierley, P., Patil, B., & Ravishankar, S. (2020, October). Understanding the Cross-contamination of Melons Via Environmental Matrices Under Field Conditions and Prevalence of Foodborne Pathogens. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Park, R., Rowlands, D., Porchas, M., Brierley, P., Patil, B., & Ravishankar, S. (2020, October). Understanding the Cross-contamination of Melons Via Environmental Matrices Under Field Conditions and Prevalence of Foodborne Pathogens. International Association for Food Protection (IAFP) Annual Conference. Virtual- Zoom: IAFP.
• Ravishankar, S. (2020, April 30). Emerging Foodborne Microbial Threats: Challenges & Control Strategies.. International Webinar Series “Novel Microbes & Newer Threats”. Zoom: Sathyabama Institute of Science & Technology, Indian Association of Applied Microbiologists, California University of Science & Medicine-.
• Ravishankar, S. (2020, August). Is UV exposure of irrigation water a trigger for the formation of VBNC Salmonella?. Arizona Iceberg Lettuce Research Council Meeting. Virtual- Zoom: Arizona Iceberg Lettuce Research Council.
• Ravishankar, S. (2020, August). Natural sanitizers: A quick and effective method to control Fusarium and Downy Mildew in seeds and crops of iceberg lettuce. Arizona Iceberg Lettuce Research Council Meeting. Virtual- Zoom: Arizona Iceberg Lettuce Research Council.
• Ravishankar, S. (2020, August). Natural sanitizers: A quick and effective method to control Thrips and Aphids on iceberg lettuce. Arizona Iceberg Lettuce Research Council. Virtual- Zoom: Arizona Iceberg Lettuce Research Council.
• Ravishankar, S. (2020, December). Benefits of Asset Development Funding to Our Research and Beyond. TLA Commercialization Conversations: Asset Development. Virtual- Zoom: Tech Launch Arizona.
• Ravishankar, S. (2020, December). Current Trends in Food Safety and Food Production. International Seminar on "Novel Strategies in Drug Development. Virtual- Google Meet: Hindustan College of Arts & Sciences, Coimbatore, Tamil Nadu, India.
• Ravishankar, S. (2020, February). CONSERVE Southwest Update: Water Quality Assessment and Water Treatment.. CONSERVE Southwest Extension Advisory Panel Meeting. Yuma, AZ: University of Arizona.
• Ravishankar, S. (2020, January). Food Safety- Identify Critical Control Points and Develop Pre- & Post-harvest Strategies to Minimize Microbial Contamination.. USDA-SCRI Melons Project Annual PI Meeting/Webinar. Virtual- Zoom: Texas A & M University.
• Ravishankar, S. (2020, October). Symposium Talk "Adoption of Emerging Technologies by the Food Industry Worldwide: Issues and Challenges". International Association for Food Protection Annual Meeting Symposium "A Global Perspective on New Generation of Food Processing/Preservation Techniques for Food Safety: Riding the Tides of Clean Labels". Virtual- Zoom: International Association for Food Protection.
• Ravishankar, S., & Law, B. (2020, July). Green & Clean Sanitizers. National Council of Entrepreneurial Tech Transfer (NCET2) virtual conference- online showcase of “COVID-19 Innovations Today and Beyond”. Virtual- Zoom: NCET2.
• Ravishankar, S., & Law, B. (2020, July). Green & Clean Sanitizers. TLA Roundtable with Industry. Virtual- Zoom: Tech Launch Arizona.
• Rossete, J., Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2020, October). Determination of the Shelf-Life and Keeping Quality of Melons Grown in Different Regions with Respect to Background Microflora, Prevalence of Foodborne Pathogens and Variances in Netting Densities. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Zhu, L., Wei, Q., Brielrley, P., Porchas, M., Patil, B., & Ravishankar, S. (2020, October). Plant-based Antimicrobials Inactivate Salmonella enterica and Listeria monocytogenes on Melon Rinds. International Association for Food Protection (IAFP) Annual Conference. Virtual- Zoom: IAFP.
• Zhu, L., Wei, Q., Brierley, P., Porchas, M., Patil, B., & Ravishankar, S. (2020, October). Plant-based Antimicrobials Inactivate Salmonella enterica and Listeria monocytogenes on Melon Rinds. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Oliveras, V., & Ravishankar, S. (2019, August 1). Efficacy of ozone against Salmonella Newport in recycled and non-recycled spinach wash water. CONSERVE Summer Internship Webinar. University of Arizona: University of MD.
• Rao, A., & Ravishankar, S. (2019, April 9). Cleaner and Greener Alternatives for Safe Food- It’s Essential!. Maricopa Environmental Health Services Department Training for Health Inspectors. Phoenix, AZ.
• Rao, A., & Ravishankar, S. (2019, June 24). Cleaner and Greener Alternatives for Safe Food- It’s Essential!. USDA-Ag Discovery Camp. University of Arizona.
• Ravishankar, S. (2019, Jan 7). Food Safety- Identify Critical Control Points and Develop Pre- & Post-harvest Strategies to Minimize Microbial Contamination. USDA-SCRI Melons Project Annual PI Meeting/Webinar. Tucson, AZ.
• Ravishankar, S. (2019, June 27). Cleaner and Greener Alternatives for Safe Food- It’s Essential!. Special Seminar- Sathyabama University, Chennai, India. Chennai, India: Sathyabama University.
• Ravishankar, S. (2019, November). Research Opportunities: Food Safety Lab- Creating a Safer Farm to Fork Journey. Microbiology Program Information Blitz- Faculty "Elevator Pitches". Tucson, AZ.
• Ravishankar, S., & Gerba, C. (2019, July 14). CONSERVE: Activities 1b & 3b- Analysis of Water Samples and Ozone Treatments. CONSERVE Annual PI Meeting. University of MD, College Park, MD: University of MD.
• Betancourt, W., Zhu, L., Ravishankar, S., Rock, C., Ikner, L., & Gerba, C. (2018, October). Pathogen occurrence in treated wastewater intended for irrigation.. 11th International Conference on Irrigation and Drainage: Water Reuse and Non-Traditional Water Sources for Irrigated Agriculture. Mesa, AZ.. Mesa, AZ.
• Ravishankar, S. (2018, April). Chico Wash: An Organic Sanitizer Effective Against Foodborne Pathogens on Fresh Produce. Presentation to Miles Chemical Company. Tucson, AZ.
• Ravishankar, S. (2018, April). Ravishankar Lab- Research/Testing Activities & Capabilities. Presentation to Miles Chemical Company. Tucson, AZ.
• Ravishankar, S. (2018, February). Analyzing Non-traditional Water Sources for Foodborne Pathogenic Bacteria & Indicator Microorganisms & Evaluation of Treatment Technologies. CONSERVE Southwest Extension Advisory Panel Meeting, Yuma, AZ. Yuma, AZ.
• Ravishankar, S. (2018, February). Majors and Research Opportunities at the School of Animal & Comparative Biomedical Sciences. Southwest Ag Summit, Yuma, AZ. Yuma, AZ.
• Ravishankar, S. (2018, January). Safer Salads & Grilled Meats: Clean and Green Approaches to Food Safety. Spring Seminar Series, College of Public Health. College of Public Health, University of Arizona, Tucson, AZ: College of Public Health.
• Ravishankar, S. (2018, Spring). Identify Critical Control Points and Develop Pre- & Post-harvest Strategies to Minimize Microbial Contaminati. USDA-SCRI- Melons Annual PI Meeting. Tucson, AZ.
• Ravishankar, S., & Rao, A. (2018, July). Analyzing Non-traditional Water Sources for Foodborne Pathogenic Bacteria and Indicator Microorganisms & Evaluation of Treatment Technologies. CONSERVE Annual PI Meeting, University of MD, College Park, MD. University of Maryland, College Park, MD: University of Maryland.
• Ravishankar, S. (2017, August). Research Activities- Ravishankar Lab. Nutritional Sciences Research Datablitz Presentations. Tucson, AZ.
• Ravishankar, S. (2017, August). Research Update- Analysis of Water Samples for Bacteria and Ozone Technology for Water Treatment. CONSERVE Annual Meeting. University of MD, College Park, MD: School of Public Health, University of MD, College Park, MD.
• Ravishankar, S. (2017, July). Keynote Speaker- Recent Trends in Food Microbiology. Invited National Seminar at the Sathyabama University, Chennai, India. Chennai, India: Center for Drug Discovery & Development, Sathyabama University, Chennai, India.
• Ravishankar, S. (2017, July). Safer Salads and Grilled Meats: Clean and Green Approaches. Invited Seminar at the Sathyabama University, Chennai, India. Chennai, India: Center for Drug Discovery & Development, Sathyabama University, Chennai, India.
• Ravishankar, S. (2017, October). Safer Salads and Grilled Meats: Clean and Green Approaches to Food Safety. Invited Seminar at the College of Agriculture & Life Sciences- Frontiers in Life Sciences Research Seminar Series. Tucson, AZ.
• Ravishankar, S. (2017, October). Safer Salads and Grilled Meats: Clean and Green Approaches. Invited Seminar at the Fujian University, Fuzhou, China. Fuzhou, China: Department of Food Science, Fujian University, Fuzhou, China..
• Ravishankar, S. (2016, August). Plant Essential Oils: Clean and Green Applications. Invited talk & Featured Speaker at the Live Bare Conference Organized by Yor Health. Las Vegas, NV: Yor Health.
• Ravishankar, S. (2016, August). Safer salads and grilled meats: Clean and green approaches. Invited talk at the American Chemical Society Annual Meeting- Symposium 'Natural and Bio-based Antimicrobials for Food Applications". Philadelphia, PA: American Chemical Society.
• Ravishankar, S. (2016, February). Food Microbiology & Safety- Job and Internship Opportunities. Invited talk at the Microbiology club, University of Arizona. Tucson, AZ: Microbiology Club.
• Ravishankar, S. (2016, March). Safer salads and Grilled Meats: clean and green approaches. Invited Seminar at the Department of Nutritional Sciences, University of Arizona. Tucson, AZ.
• Ravishankar, S. (2016, March). Safer salads and grilled meats: Clean and green approaches. Invited talk at the Maricopa County Environmental Services Department. Phoenix, AZ: Maricopa County Environmental Services Department.
• Dev Kumar, G., Patel, J., & Ravishankar, S. (2015, July). Persistence and internalization of Salmonella on/in organic spinach sprout: Exploring the contamination route. Annual Meeting of the International Association for Food Protection. Portland, OR.
• Ravishankar, S. (2015, April). Food Microbiology & Safety- Job and Internship Opportunities. Invited talk at the Microbiology club, University of Arizona. Tucson,AZ: Micro Club.
• Ravishankar, S. (2015, April). Safer salads and grilled meats: Clean and green approaches. Invited talk at the USDA-Western Regional Research Center. Albany, CA.
• Ravishankar, S. (2015, May). Career Day- Summit View Elementary School- Faculty/Scientist Profession. Invited talk at Summit View elementary school. Tucson, AZ: Summit View Elementary School.
• Ravishankar, S. (2015, November). Safer salads and grilled meats: Clean and green approaches.. Invited talk at the Annual Registered Sanitarians Conference. Phoenix, AZ.
• Ravishankar, S. (2015, October). Arizona's Food Microbiology Experts. Invited talk for TellSpec Inc.. Tucson, AZ.
• Ravishankar, S. (2015, October). Safer salads: clean and green approaches. Invited seminar at the Department of Horticultural Sciences, Texas A & M University. College Station, TX: Texas A & M University.
• Dev Kumar, G., & Ravishankar, S. (2014, July). Detection of stressed Salmonella enterica from Iceberg lettuce irrigation and processing water.. Arizona Iceberg Lettuce Research Council Quarterly Meeting. Yuma, AZ.
• Dev Kumar, G., & Ravishankar, S. (2014, July). Efficacy of sequential dual hurdle treatments- ozone and plant antimicrobials in reducing Salmonella enterica on iceberg lettuce.. Arizona Iceberg Lettuce Research Council Quarterly Meeting. Yuma, AZ.
• Dev Kumar, G., & Ravishankar, S. (2014, June). Mesquite Flour- Microbiology & Food Safety. Mesquite Workshop- New Agricultural Traditions for an Ancient Food. Benson, AZ: UA-CALS, Western SARE, BAJA-Arizona.
• Dev Kumar, G., Patel, J., & Ravishankar, S. (2014, August). Comparative Evaluation of Factors Affecting Escherichia coli Biofilms on Organic Leafy Green Wash Water Contact Surface.. Annual Meeting of the International Association for Food Protection. Indianapolis, IN.
• Ravishankar, S. (2014, February). Improving the Safety & Quality of Organic Leafy Greens. National Webinar hosted by the eOrganic. Tucson, AZ and webcast nationwide: eOrganic.
• Ravishankar, S. -. (2013, September). Fresh Produce: Farm to Fork Food Safety. Food Safety Research Update Meeting with the Yuma Fresh Produce Growers. Yuma, AZ: University of Arizona.
• Ravishankar, S. (2012). Improving the Safety and Post-harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm-to-Fork Continuum. Organic Leafy Greens Project PI Meeting.
• Ravishankar, S. (2012). Safer Salads: Clean and Green Approaches. Yuma Fresh Vegetable Association Annual Meeting. Yuma, AZ: Yuma Fresh Vegetable Association.
• Ravishankar, S. (2012, March). Food Safety and Control of Foodborne Pathogens Using Natural Antimicrobials. Seminar presented to the Microbiology Club.
• Ravishankar, S. -. (2012, June). Antimicrobial activity of spices, their active components and plant extracts against foodborne pathogenic bacteria.. IFT Symposium- Assessment and mitigation of risk with the use of spices and other dry ingredients in the food industry. Las Vegas, Nevada: IFT.
• Ravishankar, S. (2011). Control of Foodborne Pathogenic Bacteria Using Natural Antimicrobials. Food Safety Retreat. Tucson, AZ.
• Ravishankar, S. (2011). Improving the Safety and Post-harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm-to-Fork Continuum. Organic Leafy Greens Project PI Meeting.
• Ravishankar, S. (2011). Improving the Safety and Quality of Organic Leafy Greens. Fresh Produce Safety: Research Update Meeting with the Yuma Fresh Produce Growers. Yuma, AZ: Yuma Fresh Produce Growers.
• Ravishankar, S. (2011, January). Improving the Safety and Quality of Fresh Produce. Food Safety Summit, Yuma, AZ. Yuma, AZ.
• Ravishankar, S. (2011, May). Food Safety and Control of Foodborne Pathogens Using Natural Antimicrobials. Arizona Senior Academy Spring seminar series.

Poster Presentations

• Alshahrani, S., Getchell, K., Raygoza, K., Bains, K., Murell, V., Porchas, M., Brierley, P., Patil, B., & Ravishankar, S. (2021, October). A Comparison of Initial Background Microbiota on Surface of Melons Grown in Different Regions of the United States.. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Arellano, S., Zhu, L., Law, B., & Ravishankar, S. (2021, July). Plant-based Microemulsions Inactivate Escherichia coli O157:H7 and Pseudomonas fluorescens on Iceberg Lettuce and Improve Visual Quality during 28-Day Storage.. International Association for Food Protection (IAFP) Annual Conference. Phoenix, AZ: IAFP.
• Rowlands, D., Raygoza, K., Porchas, M., Brierley, P., Patil, B., & Ravishankar, S. (2021, October). Attachment Strength of Salmonella enterica serovar Newport and Listeria monocytogenes on Melon Hybrids Grown in Five Different Regions of the United States. Annual Food Safety Conference. Virtual- Zoom: University of Arizona Food Safety Consortium.
• Arellano, S., & Ravishankar, S. (2020, February). Green Sanitizers: Improved Safety and Shelf-life of Iceberg Lettuce Washed with Plant-based Antimicrobial Microemulsions. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Kaneshamoorthy, S., Mai, H., Ravishankar, S., & Dhar, A. (2020, February). Efficacy of Natural Compounds Against Vibrio parahaemolyticus causing Acute Hepatopancreatic Necrosis Disease (APHND) in Pacific White Shrimp (Penaeus vannamei). Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Nguyen, M., & Ravishankar, S. (2020, February). Antibiotic Resistance and Susceptibility of Bacterial Isolates from Various Irrigation Water Sources.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Oliveras, V., & Ravishankar, S. (2020, February). Efficacy of ozone against Salmonella Newport in recycled and non-recycled spinach wash water.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Park, R., Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2020, February). Understanding Cross-Contamination of Melons via Environmental Matrices Under Field Conditions.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Assocation.
• Rao, A., Porchas, M., Oatil, B., Ravishankar, S., & Brierley, P. (2020, February). Determination of the Shelf-Life and Keeping Quality of Melons Grown In Different Regions With Respect To Background Microflora, Prevalence of Foodborne Pathogens and Variances in Netting Densities.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Vitha, S., & Ravishankar, S. (2020, January). Surface Texture Analysis of Melon Rind Using 3D Reconstruction from SEM Stereo Image.. Texas Society for Microscopy Conference.. College Station, TX: Texas Society for Microscopy.
• Wei, Q., Torres, M., Porchas, M., Fang, T., Brierley, P., Patil, B., & Ravishankar, S. (2020, February). Attachment Strength of Foodborne Pathogens on Different Melon Varieties from Various Regions in the United States.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Zhu, L., Torres, M., Betancourt, W., Gerba, C., & Ravishankar, S. (2020, February). Incidence of Fecal Indicator and Pathogenic Bacteria in Reclaimed and Return Flow Waters in Arizona, USA.. Southwest Agricultural Summit. Yuma, AZ: Yuma Fresh Vegetable Association.
• Arellano, S., & Ravishankar, S. (2019, December). Green Sanitizers: Improved Safety and Shelf-life of Iceberg Lettuce Washed with Plant-based Antimicrobial Microemulsions. Annual GIDP Student Research Showcase. Tucson, AZ.
• Arellano, S., & Ravishankar, S. (2019, October). Green Sanitizers: Improved Safety and Shelf-life of Iceberg Lettuce Washed with Plant-based Antimicrobial Microemulsions. Annual Food Safety Conference. Tucson, AZ.
• Dev Kumar, G., & Ravishankar, S. (2019, July). Ozonized Water with Plant Antimicrobials: An Effective Method to Inactivate Salmonella enterica on Iceberg Lettuce in Produce Wash Water. International Association for Food Protection Annual Meeting. Louisville, Kentucky.
• Kaneshamoorthy, S., Mai, H., Ravishankar, S., & Dhar, A. (2020, October). Efficacy of Natural Compounds Against Vibrio parahaemolyticus causing Acute Hepatopancreatic Necrosis Disease (APHND) in Pacific White Shrimp (Penaeus vannamei). Annual Food Safety Conference. Tucson, AZ: Smith Endowment.
• Nguyen, M., & Ravishankar, S. (2019, October). Antibiotic Resistance and Susceptibility of Bacterial Isolates from Various Irrigation Water Sources. Annual Food Safety Conference. Tucson, AZ.
• Oliveras, V., & Ravishankar, S. (2019, October). Efficacy of ozone against Salmonella Newport in recycled and non-recycled spinach wash water. Annual Food Safety Conference. Tucson, AZ.
• Park, R., Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2019, July). Understanding Cross-Contamination of Melons via Environmental Matrices Under Field Conditions. International Association for Food Protection Annual Meeting. Louisville, Kentucky.
• Park, R., Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2019, October). Understanding the Cross-Contamination of Melons via Environmental Matrices Simulating Field Conditions. Annual Food Safety Conference. Tucson, AZ.
• Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2019, July). Determination of the Shelf-Life and Keeping Quality of Melons Grown In Different Regions With Respect To Background Microflora, Prevalence of Foodborne Pathogens and Variances in Netting Densities. International Association for Food Protection Annual Meeting. Louisville, Kentucky.
• Rao, A., Porchas, M., Patil, B., Brierley, P., & Ravishankar, S. (2019, October). Microbial Quality During Storage, Prevalence of Foodborne Pathogens and Salmonella Colonization Based on Variances in Netting Densities of Melons Grown in Different Regions of the United States. Annual Food Safety Conference.
• Wei, Q., Torres, M., Porchas, M., Fang, T., Brierley, P., Patil, B., & Ravishankar, S. (2019, July). Attachment Strength of Foodborne Pathogens on Different Melon Varieties from Various Regions in the United States. International Association for Food Protection Annual Meeting. Louisville, Kentucky.
• Zhu, L., Torres, M., Betancourt, W., Gerba, C., & Ravishankar, S. (2019, July). Incidence of Fecal Indicator and Pathogenic Bacteria in Reclaimed and Return Flow Waters in Arizona, USA. International Association for Food Protection Annual Meeting. Louisville, Kentucky.
• Zhu, L., Torres, M., Betancourt, W., Gerba, C., & Ravishankar, S. (2019, October). Incidence of Fecal Indicator and Pathogenic Bacteria in Reclaimed and Return Flow Waters in Arizona, USA. Annual Food Safety Conference. Tucson, AZ.
• Rao, A., & Ravishankar, S. (2017, July). Effect of essential oils and their active components on Salmonella enterica serovar Newport- Inactivation or induction into the Viable But Non-Culturable (VBNC) state?. Annual Meeting of the International Association for Food Protection. Tampa, FL.
• Wei, Q., Torres, M., Porchas, M., Fang, T., Patil, B., Brierley, P., & Ravishankar, S. (2019, October). Attachment Strength of Foodborne Pathogens on Different Melon Varieties from Various Regions in the United States. Annual Food Safety Conference. Tucson, AZ.
• Green, J., Keelara, S., Ravishankar, S., & Patel, J. (2016, July). Antimicrobial Effect of Essential Oils against E. coli O157:H7 and Salmonella on Fresh Herbs. Annual Meeting of the Institute of Food Technologists. Chicago, IL.
• Joshi, K., & Ravishankar, S. (2016, March). Evaluating the Impact of Plant-Based Antimicrobials on Sensory Properties of Organic Leafy Greens. Abstract submitted to the Annual IFT meeting.
• Joshi, K., Ravishankar, S., Nolte, K. D., & Siemens, M. C. (2016, August). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and the efficacy of plant antimicrobials and organic sanitizers. Annual Meeting of the International Association for Food Protection.
• Kumar, G. D., Zhu, L., Nolte, K. D., Siemens, M. C., Fonseca, J., & Ravishankar, S. (2016, August). Modified coring tool designs reduce iceberg lettuce cross-contamination. Annual Meeting of the International Association for Food Protection. St. Louis, MI.
• Zhu, L., & Ravishankar, S. (2016, August). Effectiveness of wash water containing plant antimicrobials against Salmonella Newport on organic leafy greens during reuse. Annual Meeting of the International Association for Food Protection. St. Louis, MI.
• Brooks, J., Ravishankar, S., & Jaroni, D. (2015, July). Evaluating the Re-usability of Organic Sanitizers in Reducing Escherichia coli O157:H7 on Organic Leafy Greens. Annual Meeting of International Association for Food Protection. Portland, OR.
• Govindaraj, D. K., Ravishankar, S., & Patel, J. (2015, October). Persistance and internalization of Salmonella on/in organic spinach sprout: Exploring the contamination route. 2015 CALS Poster Forum.
• Kakani, R., Ravishankar, S., & Jaroni, D. (2015, July). Inhibitory Activity of Plant-derived Antimicrobials against Lactobacillus brevis on Organic Leafy Greens. Annual Meeting of International Association for Food Protection. Portland, OR.
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, October). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and efficacy of plant antimicrobials and organic sanitizers. 2015 CALS Poster Forum.
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, October). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and efficacy of plant antimicrobials and organic sanitizers. Cactus- Institute of Food Technologists Regional Meeting.
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, September). Understanding the attachment of Salmonella Newport on lettuce coring tools and efficacy of organic sanitizers against the pathogen. 2015 Food Safety Conference.
  More info

  This was an abstract submitted to the food safety conference. The abstract was accepted but the poster presentations for this conference were cancelled due to the unavailability of the meeting room.
• Ravishankar, S., Litt, P. K., & Jaroni, D. (2015, February). Antimicrobial Efficacy of Fulvic Acid Formulations against Escherichia coli O157:H7 on Bagged Organic Leafy Greens at Refrigeration Temperatures. Annual FAPC Research Symposium, Oklahoma State University. Stillwater, OK.
• Schneider, A., Freidman, M., Patel, J., Jaroni, D., & Ravishankar, S. (2015, July). Clove Bud Oil, Its Active Component, and Combination Treatments with Plant Extracts Inactivate Multi-Drug Resistant Salmonella Newport on Organic Leafy Greens. Annual Meeting of the International Association for Food Protection. Portland, OR.
• Zhu, L., Mild, R., & Ravishankar, S. (2015, July). Efficacy of a Citric Acid based Organic Sanitizer against Salmonella enterica and Escherichia coli K-12 on organic leafy greens during wash water recycling.. Annual Meeting of the International Association for Food Protection. Portland, OR.
• Jaroni, D., Litt, P. K., Ravishankar, S., & Brooks, J. (2014, August). Inhibitory Activity of Hydrogen Peroxide, Water and Organic Sanitizers against Escherichia coli O157:H7 on Organic Leafy Greens.. Annual Meeting of the International Association for Food Protection. Indianapolis, IN.
• Litt, P. K., Ravishankar, S., & Jaroni, D. (2014, August). Antimicrobial Efficacy of Fulvic Acid Formulations against Escherichia coli O157:H7 on Bagged Organic Leafy Greens at Refrigeration Temperatures. Annual Meeting of the International Association for Food Protection. Indianapolis, IN.
• Rada, X., Todd, J., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. (2014, August). Effects of Combination Treatments of Essential Oils and a Plant Extract Against Multi – drug Resistant Salmonella Newport on Organic Leafy Greens.. Annual Meeting of the International Association for Food Protection. Indianapolis, IN.
• Schneider, A., & Ravishankar, S. (2014, October). Antimicrobial Activity of Essential Oil X Against Multi-Drug Resistant Salmonella enterica on Organic Leafy Greens.. Annual Food Safety Conference of the UA-Food Safety Consortium. Tucson, AZ.
• Zhu, L., & Ravishankar, S. (2014, August). Efficacy of a Citric Acid based Organic Sanitizer against Salmonella enterica and Background Microflora on Fresh-cut Celery and Leeks.. Annual Meeting of the International Association for Food Protection. Indianapolis, IN.
• Denton, J., Jeyasundara, B., Ravishankar, S. -., & Jaroni, D. (2013, August). Antimicrobial activity of cinnamon, oregano and lemongrass essential oils against Escherichia coli O157:H7 on organic leafy greens stored at refrigeration temperatures. International Association for Food Protection Annual Meeting 2013. Charlotte, NC: University of Arizona.
• Denton, J., Ravishankar, S. -., & Jaroni, D. (2013, August). Antimicrobial efficacy of cinnamaldahyde, carvacrol and citral against Escherichia coli O157:H7 on organic leafy greens at 4oC. International Association for Food Protection Annual Meeting 2013,. Charlotte, NC: University of Arizona.
• Dev Kumar, G., Patel, J., & Ravishankar, S. -. (2013, October). Comparative evaluation of factors affecting Escherichia coli biofilms on organic leafy green wash water equipment surfaces.. 2013 Food Safety Conference, University of Arizona Food Safety Consortium. Tucson, AZ: University of Arizona.
• Jaroni, D., Jeyasundera, B., Ramirez-Lopez, L., & Ravishankar, S. -. (2013, August). Efficacy of roselle (Hibiscus sabdariffa) calyx formulations against Escherichia coli O157:H7 on bagged organic leafy greens.. International Association for Food Protection Annual Meeting 2013. Charlotte, NC: University of Arizona.
• Jeyasundera, B., Jaroni, D., Ramirez-Lopez, L., & Ravishankar, S. -. (2013, August). Antimicrobial effects of olive, apple and grapeseed extracts against Escherichia coli O157:H7 on organic leafy greens stored at 4° C. International Association for Food Protection Annual Meeting 2013. Charlotte, NC: University of Arizona.
• Rada, X., Todd, J., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. -. (2013, October). Synergistic effects of combination treatments of essential oils and a plant extract against multi-drug resistant Salmonella enterica on organic leafy greens.. 2013 Food Safety Conference, University of Arizona Food Safety Consortium. Tucson, AZ: University of Arizona.
• Ravishankar, S. -., Bevington, R., & Nolte, K. (2013, August). How to: making an informative video from start to finish. Annual Meeting of the American Society for Horticultural Sciences. Palm Desert, CA: University of Arizona.
• Ravishankar, S. -., Zhu, L., Friedman, M., Olsen, C., McHugh, T., & Jaroni, D. (2013, August). . Use of edible films containing plant antimicrobials to inhibit Pseudomonas fluorescens in bagged organic lettuce.. International Association for Food Protection Annual Meeting 2013. Charlotte, NC: University of Arizona.
• Ravishankar, S. -., Zhu, L., Olsen, C., McHugh, T., Friedman, M., & Jaroni, D. (2013, July). Apple, carrot, and hibiscus edible films containing plant antimicrobials inactivate Salmonella Newport in packaged organic leafy greens.. Institute of Food Technologists Annual Meeting 2013. Chicago, IL: University of Arizona.
• Todd, J., Friedman, M., Patel, J., Jaroni, D., & Ravishankar, S. -. (2013, July). The antimicrobial effects of cinnamon oil against multi-drug resistant Salmonella Newport on organic leafy greens. Institute of Food Technologists Annual Meeting 2013. Chicago, IL: University of Arizona.
• Tollerson, R., Dev Kumar, G., & Ravishankar, S. -. (2013, October). Role of environmental factors in the transfer of Salmonella enterica to iceberg lettuce leaves and biophotonic imaging of transfer sites.. 2013 Food Safety Conference, University of Arizona Food Safety Consortium. Tucson, AZ: Universitry of Arizona.
• Moore-Neibel, K., PatelJ, ., Friedman, M., & Ravishankar, S. (2012, July). Antimicrobial Activity of Oregano Oil Against Salmonella enterica on Organic Leafy Greens at Varying Exposure Times and Storage Temperatures. International Association for Food Protection (IAFP) Annual Meeting 2012. Providence, RI.
• Ravishankar, S., Bright, K., FonsecaJ, ., Gerba, C., Knolte, K., Jaroni, D., Patel, J., & Friedman, M. (2012, October). Improving the Safety and Post-Harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm to Fork Continuum.. USDA-NIFA-Organic Program Project Directors Meeting. USDA-NIFA Waterfront Center, Washington, DC.
• Reyna-Granados, J., Joens, L., Friedman, M., & Ravishankar, S. (2012, July). Concentration and Time-dependent Inactivation of Escherichia coli O157:H7 by Plant Extract. IAFP 2012. Providence, RI.
• Rojas, D., Todd, J., Friedman, M., Jaroni, D., & Ravishankar, S. (2012, June). Antimicrobial Activity of Hibiscus Tea and Grapeseed and Green Tea Extracts Against Antibiotic-Resistant Salmonella Newport on Organic Leafy Greens.. Institute of Food Technologists (IFT) Annual Meeting 2012. Las Vegas, NV.
• Rounds, L., Havens, C., Feinstein, Y., Friedman, M., & Ravishankar, S. (2012, June). Concentration-dependant Inhibition of Escherichia coli O157:H7 and Potentially Carcinogenic Heterocyclic Amines in Heated Ground Beef Patties by Apple, Olive and Onion Powders and Clove Bud Oil.. IFT Annual Meeting 2012. Las Vegas, NV.
• Tood, J., & Ravishankar, S. (2012, June). Survival of Escherichia coli O157:H7 and Salmonella Newport in Various Commercial Organic Compost. IFT Annual Meeting 2012. Las Vegas Convention Center, Las Vegas, NV.
• Zhu, L., & Ravishankar, S. (2012, July). Efficacy of Sanitizers Approved for Organic Use Against Salmonella enterica on Organic Leafy Greens. IAFP 2012. Providence, RI..
• Chen, C., Ravishankar, S., & Marchello, J. (2011, August). The Effectiveness of Plant Compounds/Extracts against Salmonella Typhimurium DT104 in Ground Por. IAFP 2010. Milwaukee, WI.
• Moore, K., Patel, J., Jaroni, D., Friedman, M., & Ravishankar, S. (2011, August). Antimicrobial Activity of Plant Extract/Concentrate Rinses against Salmonella enterica on Organic Leafy Green. IAFP 2011. Milwaukee, WI.
• Ravishankar, S., Zhu, L., Olsen, C., Jaroni, D., McHugh, T., & Friedman, M. (2011, August). Inactivation of Listeria monocytogenes on Ham and Bologna Using Apple, Carrot, and Hibiscus Based Edible Films Containing Carvacrol and Cinnamaldehyde.. International Association for Food Protection (IAFP) Annual Meeting 2010. Milwaukee, WI.
• Rounds, S., Havens, C., Feinstein, Y., Friedman, M., & Ravishankar, S. (2011, August). Simultaneous Inactivation of Escherichia coli O157:H7 and Reduction of Potentially Carcinogenic Heterocyclic Amines in Heated Ground Beef Patties by Plant Compounds. IAFP 2010. Milwaukee, WI.

Others

• Ravishankar, S. (2021, March). Panelist in "Convo With Cantwell". Dr. Ravishankar was invited as a Woman Inventor/Entrepreneur Panelist and participated in “Convo with Cantwell” zoom chat, where she answered questions from Dr. Betsy Cantwell, UA Senior Vice President for Research and Innovation on March 18, 2021. This was an event conducted as part of Women’s History Month to talk about their achievements and inspire future innovation..
• Ravishankar, S. (2021, March). TLA video "Women Make it Happen". Dr. Ravishankar was one of the three Woman Inventors/Entrepreneurs interviewed for a TLA Women Inventor’s Campaign (Women Make It Happen!) to inspire UA women researchers, faculty and graduate students to come to TLA with impactful inventions stemming from their work. Three videos were created from the interview recordings for Honoring Women’s History Month and showcased in the Tech Launch Arizona Newsletter on 3/31/2021. The links to the videos are given below: Women Make It Happen: Meet Three UArizona Inventors | Tech Launch Arizona https://youtu.be/svkCI5xonVk.
• Ravishankar, S. (2020, November). Daily Wildcat Podcast. Dr. Ravishankar was interviewed by a reporter for 60 min about her interest, career and research in food safety. She also provided specific messages for students about selecting a career in food safety. Link to the Daily Wildcat Podcast: https://open.spotify.com/episode/0b9gXEvGrsJbKcmxbIDUya?si=AwwPTk84TM6RkqLc7E_t3w.
• Tolu, A., & Ravishankar, S. (2020, October). Clean Label Shelf-lLfe. Interviewed and contributed towards the article for Food Quality & Safety Magazine.
• Betancourt, W. Q., Morrison, C., Hurtado, D., Zhu, L., Ravishankar, S., Brassill, N., Rock, C., Ikner, L., & Gerba, C. (2018, October). Assessment of pathogens in treated wastewater intended for crop irrigation.. Abstract submitted to 6th International Conference on Food and Environmental Virology. Phoenix, AZ Oct. 1-10, 2018..
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, September). Understanding the attachment of Salmonella Newport on lettuce coring tools and efficacy of organic sanitizers against the pathogen. 2015 Food Safety Conference.
• Ravishankar, S., & Dev Kumar, G. (2015, September). Effects of environmental conditions on transfer rates of Salmonella enterica and Escherichia coli O157:H7 from soil, dust and irrigation water to iceberg lettuce surfaces. Arizona Iceberg Lettuce Research Council Report.
• Ravishankar, S., Jaroni, D., Bright, K., Fonseca, J., Patel, J., Gerba, C., Friedman, M., & Nolte, K. (2015, December). Improving the Safety and Post-harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm-to-Fork Continuum. USDA-NIFA-Organic Research and Extension Initiative Report.
• Fonseca, J., Sanchez, C., & Ravishankar, S. (2012, Fall). Assessing and Managing the Health Risks of Irrigation Water in the Lower Colorado River Basin. USDA-CSREES.
• Ravishankar, S. (2012, Summer). Plant Compounds to Inactivate Salmonella Newport on Organic Leafy Greens. WAESO-NSF.
• Ravishankar, S., Bright, K., Fonseca, J., Patel, J., Gerba, C., Jaroni, D., Friedman, M., & Nolte, K. (2012, Fall). Improving the Safety and Post-Harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm to Fork Continuum. USDA-NIFA-OREI.
• Fonseca, J., Ravishankar, S., & Sanchez, C. (2011, Fall). Effect of microflora competition on growth and survival of Escherichia coli O157:H7 in leafy vegetables. Arizona Leafy Greens Marketing Agreement.
• Fonseca, J., Sanchez, C., & Ravishankar, S. (2011, Fall). Assessing and Managing the Health Risks of Irrigation Water in the Lower Colorado River Basin. USDA-CSREES.
• Ravishankar, S., Jaroni, D., Bright, K., Fonseca, J., Patel, J., Gerba, C., Friedman, M., & Nolte, K. (2011, January). Improving the Safety and Post-Harvest Quality of Field Grown Organic Leafy Greens: Assessment of Good Agricultural/Production Practices Along the Farm to Fork Continuum. USDA-NIFA-OREI.
  More info

  Exact Date: 01/07/2011
• Fonseca, J., Ravishankar, S., & Sanchez, C. (2010, Fall). Effect of Microflora Competition on Growth and Survival of Escherichia coli O157:H7 in Leafy Vegetables. Arizona Leafy Greens Marketing Agreement.