Study of microbial contamination of processed fresh vegetables and lettuce

Investigations of microbial contamination and species composition of the Enterobacteriaceae family in fresh vegetables and lettuce has been conducted. The objects of study were new types of fresh ready-to-eat vegetable foods - salads, sliced vegetables and mixtures thereof, sampled at the main stages of production, including washing, antimicrobial treatment with sodium hypochlorite, and packaging in the film under vacuum. Quantitative analysis of Enterobacteriaceae levels in fresh and packaged vegetables and salads showed that their part in the total amount of microbial contaminants is large enough. Average Enterobacteriaceae content ranged from 2,14 to 3,34 lg cfu/g, reaching in some samples values 4,38-4,74 lg, comparable with the levels of total bacteria. Considerable species diversity of microflora contaminating ready-to-eat vegetable products has been found. Bacteria of the genera Enterobactel; Pantoea, Citrobacter, Serratia, Pseudomonas, Kluyvera, Klebsiella, Escherichia, Rahnella, Acinetobacter were found in the salads and sliced vegetables. In the tested samples most frequently detected Enterobacter spp. - 37% of identified strains and Pantoea spp - 25% of strains. The data on the composition and levels of microbial contaminants in vegetable and salad products highlight not only the need to monitor coliform bacteria - traditional indicators of faecal contamination of raw materials, but also the need to introduce criteria for the amount of Enterobacteriaceae.