Effects of sanitizer time and concentration in produce washing water on cross-contamination by Salmonella and Escherichia coli O157:H7
Polsky, Jacob Alan
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Sanitizer strength and exposure time effects on cross-contamination of produce in wash waters were determined. Tomatoes and cantaloupes inoculated with Salmonella and lettuce inoculated with E. coli were added to a wash tank with non-inoculated produce. Tank conditions mimiced conditions in commercial wash tanks. At time intervals, non-inoculated produce was removed from the tank and sampled for the pathogens. For all produce, cross-contamination occurred in the absence of sanitizer. With 50 ppm chlorine, 11-16% of tomatoes were positive at all sampling times, while 100 ppm chlorine prevented cross-contamination. Tomatoes (~11%) exposed to 80 ppm peroxyacetic acid were Salmonella contaminated after 2 min but after 4 min none were positive. Peroxyacetic acid prevented Salmonella cantaloupe cross-contamination, while chlorine was less effective. For lettuce, chlorine exposure was more effective than peroxyacetic acid in preventing E. coli O157:H7 cross-contamination. This data could be used when evaluating process control points.