Microbial Evaluation of Selected Fresh Produce Obtained At Retail Markets

MicrobialEvaluation of Selected Fresh Produce Obtained at Retail Markets

Richard L. Thunberg; Tony T. Tran; Reginald W. Bennett; RogerN. Matthews; Negash Belay, Journal of Food Protection ,Volume: 65 Number: 4Page: p677 — p682

The microbial quality of five types of fresh produce obtainedat the retail level was determined by standard quantitative techniques. Thesetechniques included aerobic plate count (APC), total coliform counts, Escherichiacoli counts, and yeast and mold counts. Three different methods were used todetermine total coliform counts, which consisted of MacConkey agar plate counts,Colicomplete most probable number counts, and Petrifilm E. coli (EC)plate counts. The mean APCs for sprouts, lettuce, celery, cauliflower, andbroccoli were 8.7, 8.6, 7.5, 7.4, and 6.3 log₁₀ CFU/g, respectively.MacConkey agar counts indicated that 89 to 96% of the APCs consisted ofgram-negative bacteria. Yeast and mold counts were in a range expected of freshproduce. Fresh produce was also analyzed for human pathogens. Samples wereanalyzed for Staphylococcus spp., Bacillus spp., Salmonellaspp., Listeria spp., and Campylobacter spp. One isolate of Staphylococcuswas found to be enterotoxigenic, and one species of Bacillus was alsotoxigenic. Neither Salmonellaspp. nor Campylobacter spp. weredetected in any of the produce samples. A variety of Listeria spp.,including Listeria monocytogenes, were found in fresh produce.