Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2014
Publication Date: 7/21/2014
Citation: Ukuku, D.O., Huang, L., Sommers, C.H. 2014. Survival and growth parameters of Escherichia coli 0157:H7, Salmonella Spp. and Listeria monocytogenes on cantaloupe fresh-cut pieces during storage. Journal of Food Protection. 78:1288-1295.
Interpretive Summary: Foodborne illness associated with the consumption of bacteria contaminated fresh-cut fruit and vegetables continue to be a problem for the produce industries and consumers alike. Alternative minimally processing using natural antimicrobial compounds in reducing transfer of bacteria from cantaloupe rind surfaces to flesh during fresh-cut preparation and the growth parameters of transferred bacteria was investigated. The average initial Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes recovered in fresh-cut pieces from water washed whole cantaloupe was 3.3, 3.5 and 3 log CFU/g, respectively. Populations on fresh-cut pieces from chlorinated water and Lovit sanitized whole cantaloupes were significantly lower, averaging 0.9 log CFU/g and below detection, respectively. Results showed that specific growth rate of E. coli O157:H7, Salmonella spp., and L. monocytogenes were similar. Also, this study indicates that Lovit is a better alternative sanitizer for inactivating bacteria on melon rind surfaces before fresh-cut preparation.
Technical Abstract: For health reasons, people are consuming fresh-cut fruits with or without minimal processing, thereby, exposing themselves to the risk of foodborne illness if such fruits are contaminated with bacteria pathogens. Cantaloupe rind surfaces were inoculated with a three cocktails of Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes, respectively at ~ 4.8 log CFU/cm2. Inoculated cantaloupes were washed in tap water, chlorinated (1000 mg/L) tap water and Lovit (nisin, EDTA, and organic acids), a novel sanitizer developed in our laboratory, for 5 min before preparing fresh-cut pieces. Prepared fresh-cut pieces were stored at 5, 10, 15 for 15 days and 22 C for 24h. Survival and growth parameters of E. coli O157:H7, Salmonella spp., and aerobic bacteria were analyzed using the optimized Huang growth model to calculate lag phases and growth rates at the storage temperatures. Similarly, the growth data of L. monocytogenes were analyzed using a 3-parameter logistic model. The average initial Salmonella spp., E. coli O157:H7, and L. monocytogenes populations recovered in fresh-cut pieces from water washed whole cantaloupes was 3.3, 3.5 and 3 log CFU/g, respectively. Populations on fresh-cut pieces from chlorinated and Lovit sanitized whole cantaloupes were significantly lower, averaging 0.9 log CFU/g and below detection, respectively. Storage temperature affected survival and growth of each class of bacterium on fresh-cut cantaloupe. Results showed the specific growth rates of E. coli O157:H7, Salmonella spp., and L. monocytogenes were very similar, while the background microorganisms grew 60-80 percent faster and with shorter lag phases. The results of this study indicate that Lovit is a better alternative sanitizer than chlorinated water for inactivating bacteria on melon rind surfaces.