Influence of temperature, humidity, and diluent type on survival of Salmonella spp. on the surface of raw tomatoes
Keywords:tomatoes, Salmonella, humidity, refrigeration, survival
Tomatoes are an important commodity, placing fourth among most popular vegetables in the U.S. However, fresh tomatoes lack a final pathogen elimination step and have been implicated in Salmonella-related outbreaks. The purpose of the study was to evaluate survival of Salmonella post-drying in three diluents on the surface of green mature tomatoes at 12 °C or 25 °C. Additionally, low and high air relative humidity influence was evaluated at 25 °C on pathogen survival. A five Salmonella rifampin-resistant strain cocktail was double-washed in buffered peptone water (BPW) and resuspended in 0.1% peptone, BPW, or fresh tomato serum. Inoculum (0.1 mL) was allowed to dry on the surface of tomatoes. For study I, tomatoes were placed in 12 °C and 25 °C incubators with no humidity control and sampled on days 0, 1, 3, and 5. For study II, tomatoes were sampled on days 0, 1 (biosafety hood storage) and on day 5 after storage in two 25 oC incubators (low and high relative humidity). Salmonella was recovered from tomatoes (20 mL BPW) and plated (TSA-rif80, 37 °C,
48 hours). Post-drying Salmonella counts (ca. 4.5 - 5.0 log10 CFU.mL-1) remained at 4.03 and 4.40 log10 CFU.mL-1 in serum after 5 days of storage at 12 °C and 25 °C, respectively. Conversely, corresponding counts in BPW and peptone were lower at ca. 1.4 to 1.8 and 2.2 to 2.8 log units at 12 °C and 25 °C, respectively. At low humidity, post-drying Salmonella counts showed highest decline for peptone (final 1.98 log10 CFU.mL-1) compared to BPW
(3.79 log10 CFU.mL-1) and tomato serum (4.75 log10 CFU.mL-1) on day 5. Counts declined rapidly to 0.03, 0.56, and 0.44 log10 CFU.mL-1 for peptone, BPW, and tomato serum, respectively, at high humidity on day 5. To summarize, it was shown that increased solutes have protective effect on Salmonella in desiccated conditions, while high humidity storage causes accelerated death of stationary culture within five days storage period.
Allen, R. L., Warren, B. R., Archer, D. L., Sargent, S. A., Schneider, K. R. 2005. Survival of Salmonella spp. on the surfaces of fresh tomatoes and selected packing line materials. HortTechnology, vol. 15, p. 831-836. https://doi.org/10.21273/HORTTECH.15.4.0831
Beuchat, L. R., Mann, D. A. 2008. Survival and growth of acid-adapted and unadapted Salmonella in and on raw tomatoes as affected by variety, stage of ripeness, and storage temperature. Journal of food protection, vol. 71, no. 8, p. 1572-1579. https://doi.org/10.4315/0362-028X-71.8.1572
CDC. 2002. Centers for Disease Control and Prevention. Outbreak of Salmonella serotype Javiana infections - Orlando, Florida, June 2002. Morbidity and mortality weekly reports, vol. 51, p. 683-684.
Croby, R., Lanni, V., Kistler, V., Dato, V., Weltman, A., Yozviak, C., Waller, K., Nalluswami, K., Moll, M., Lockett, J., Montgomery, S., Lyuch, M., Braden, C., Gupta, S. K., Dubois, A. 2005. Outbreaks of Salmonella infections associated with eating Roma tomatoes - United States and Canada, 2004. Morbidity and mortality weekly reports, vol. 54, p. 325-328.
FAOSTAT. 2017. Food and Agriculture Organization of the United Nations. Commodities by country. Countries by commodity. Available at: http://www.fao.org
Guo, X., Chen, J., Brackett, R. E., Beuchat, L. R. 2002. Survival of Salmonella on tomatoes stored at high relative humidity, in soil, and on tomatoes in contact with soil. Journal of food protection, vol. 65, no. 2 p. 274-279. https://doi.org/10.4315/0362-028X-65.2.274
Hirai, Y. 1991. Survival of bacteria under dry conditions; from a viewpoint of nosocomial infection. Journal of hospital infections, vol. 19, no. 3, p. 191-200. https://doi.org/10.1016/0195-6701(91)90223-U
Iturriaga, M. H., Tamplin, M. L., Escartín, E. F. 2007. Colonization of tomatoes by Salmonella montevideo is affected by relative humidity and storage temperature. Journal of food protection, vol. 70, no. 1, p. 30-34. https://doi.org/10.4315/0362-028X-70.1.30
Kramer, A., Schwebke, I., Kampf, G. 2006. How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infectious diseases, vol. 16, p.130. https://doi.org/10.1186%2F1471-2334-6-130
Kusumaningrum, H. D., Riboldi, G., Hazeleger, W. C., Beumer, R. R. 2003. Survival of foodborne pathogens on stainless steel surfaces and cross-contamination to foods. International journal of food microbiology, vol. 85, no. 3, p. 227-236. https://doi.org/10.1016/S0168-1605(02)00540-8
Lang, M. M., Harris, L. J., Beuchat, L. R. 2004. Evaluation of inoculation method and inoculum drying time for their effects on survival and efficiency of recovery of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated on the surface of tomatoes. Journal of food protection, vol. 67, no. 4, p.732-741. https://doi.org/10.4315/0362-028X-67.4.732
Li, H., Megalis, C., Tortorello, M. L. 2010. Impact of relative humidity on the survival of desiccated Salmonella cells on surfaces with peanut butter. Journal of Food Protection Supplement, vol. 73, no. sp1, p. 1-198. https://doi.org/10.4315/0362-028X-73.sp1.1
Møretrø, T., Heir, E., Mo, K. R., Habimana, O., Abdelgani, A., Langsrud, S. 2010. Factors affecting survival of Shigatoxin-producing Escherichia coli on abiotic surfaces. International journal of food microbiology, vol. 138, p. 71-77. https://doi.org/10.1016/j.ijfoodmicro.2010.01.002
Rathinasabapathi, B. 2004. Survival of Salmonella Montevideo on tomato leaves and mature green tomatoes. Journal of food protection, vol. 67, no. 10, p. 2277-2279. https://doi.org/10.4315/0362-028X-67.10.2277
Shi, X., Namvar, A., Kostrzynska, M., Hora, R., Warriner, K. 2007. Persistence and growth of different Salmonella serovars on pre- and postharvest tomatoes. Journal of food protection, vol. 70, no. 12, p. 2725-2731. https://doi.org/10.4315/0362-028X-70.12.2725
Sreedharan, A., Tokarskyy, O., Sargent, S., Schneider, K. R. 2015. Survival of Salmonella spp. on surface-inoculated forced-air cooled and hydrocooled intact strawberries, and in strawberry puree. Food control, vol 51, p. 244-250. https://doi.org/10.1016/j.foodcont.2014.11.042
Stine, S. W., Song, I., Choi, C. Y., Gerba, C. P. 2005. Effect of relative humidity on preharvest survival of bacterial and viral pathogens on the surface of cantaloupe, lettuce, and bell peppers. Journal of food protection, vol. 68, no. 7, p. 1352-1358. https://doi.org/10.4315/0362-028X-68.7.1352
Tokarskyy, O., De, J., Fatica, M. K., Brecht, J., Schneider, K. R. 2018. Survival of Escherichia coli O157:H7 and Salmonella on bruised and unbruised tomatoes from three ripeness stages at two temperatures. Journal of food protection, vol. 81, no. 12, p. 2028-2034 https://doi.org/10.4315/0362-028X.JFP-18-220
Wei, C. I., Huang, T. S., Kim, J. M., Lin, W. F., Tamplin, M. L., Bartz, J. A. 1995. Growth and survival of Salmonella montevideo on tomatoes and disinfection with chlorinated water. Journal of food protection, vol. 58, no. 8, p. 829-836. https://doi.org/10.4315/0362-028X-58.8.829
Yuk, H. G., Warren, B. R., Schneider, K. R. 2007. Infiltration and survival of Salmonella spp. on tomato surfaces labeled using a low-energy carbon dioxide laser device. HortTechnology, vol. 17, no. 1, p. 67-71. https://doi.org/10.21273/HORTTECH.17.1.67
Zhuang, R. Y., Beuchat, L. R., Angulo, F. J. 1995. Fate of Salmonella montevideo on and in raw tomatoes as affected by temperature and treatment with chlorine. Applied and environmental microbiology, vol. 61, no. 6, p. 2127-2131.
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