Food safety research for fresh produce

Jun Won Chang, Purdue University

Abstract

Recent outbreaks and recalls associated with cantaloupe contaminated with Salmonella s.v. Typhimurium and Listeria monocytogenes have led to an increasing need for methods consumers can use at home to clean and sanitize cantaloupe before consumption. Hot water (82°C) and household chemicals, such as bleach, vinegar, iodine, salt and hydrogen peroxide, were tested to determine their efficacy for the reduction of S. Typhimurium and L. monocytogenes inoculated on cantaloupe surfaces. The hot water treatment was the most effective at reducing S. Typhimurium (3.8 log reduction) and L. monocytogenes (2.5 log reduction) on the cantaloupe surface. The use of Electrochemically Activated (ECA) water to reduce S. Typhimurium and L. monocytogenes inoculated on cantaloupe surfaces was also examined for industry and farm use. ECA water is produced through the electrolysis of tap water containing dissolved sodium chloride into the anodic (anolyte; chlorine species sanitizer) and cathodic (catholyte; highly basic detergent) solutions. Combination with a UV treatment was also tested to determine if there was a synergistic sanitizing effect. The triple combination of catholyte, anolyte and UV treatment had the highest average log reduction, 3.3 for S. Typhimurium and 3.6 for L. monocytogenes of the combinations tested. A natural antimicrobial compound commonly used in the food industry was also examined. MicroGARD® 730 (Dupont Inc., Wilmington, DE, USA), is a fermented milk product that contains antimicrobial metabolites that has been shown to inhibit the growth of bacteria, yeasts and molds. Four different types of grain blends that contained various types of grains and legumes were tested with and without the addition of 0.65% w/w of MicroGARD ® 730. The samples were inoculated with 104 CFU/g of each E. coli O157:H7, S. Typhimurium, and L. monocytogenes and stored at 4°C and 10°C. The grain blends were sampled every day for 12 days (shelf-life of the product) by spread plating on a selective medium for each bacterium tested. In this study, all MicroGARD® 730 treated samples that were stored at 4°C had a steady decrease in all of the pathogens tested indicating the antimicrobial compound was effective.

Degree

M.S.

Advisors

Deering, Purdue University.

Subject Area

Food Science|Plant sciences

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