Bacterial contamination and microflora of several fresh produce

Viable counts were enumerated in 36 raw samples of 19 different vegetables. Coliform, fecal coliform, and E. coli were determined in 31 vegetable samples. Tomato was found to have the lowest viable count of 2.12 log cfu/g while radish sprout had the highest count of 9.05 log cfu/g. Although E. coli was not detected in all the vegetables tested, most of these vegetables were positive for fecal coliform. Viable counts of the tenth leaves from the outside were lower by only 1 log cfu/g than that of the outermost leaves in cabbage and lettuce. Among viable counts of vegetable parts, celery leaves, lower stems in radish sprout, and spinach were found to have the highest viable counts of 7.28 log cfu/g, 9.27 log cfu/g, and 6.10 log cfu/g respectively while lower stem in parsley had the lowest count of 5.10 log cfu/g. The microflora of the four vegetables, celery, parsley, radish, and radish sprout were determined by using biochemical methods. There were 105, 50, 48, 130, and 61 bacterial isolates from celery, lettuce, parsley, radish, and radish sprout, respectively. The predominant bacterium on the four vegetables was about 30-60% Gram-negative Flavobacterium or Xanthomonas. Other Gram-negative bacteria isolated from the vegetables include 11% Neisseria or Veillnella (celery), 18% Moraxella (radish), 15% Alcaligenes and 12% Pseudomonas (radish sprout) while Enterobacteriaceae accounted for less than 5% for each of the flora of celery, parsley, and radish sprout. On the contrary, parsley had 25% Kurthia or Bacillus, and 13% Micrococcus, both Gram-positive.