Identification and Control of Microbiological Hazards in Fermented Vegetables and Fermented Fishes Produced in Cambodia

摘要

Fpodborne outbreaks are common in Cambodia, but only a few investigating documents have been conducted due to the poor public awareness and the lack of scientific report. The objectives of this study were (ⅰ) to identify and evaluate the contamination rate of microbial hazards in fermented vegetable and fish products in Cambodia, (ⅱ) to determine histamine level in fermented fishes as well as histamine producing bacteria, and (ⅲ) to define targets for control histamine producing bacteria through starter culture (LAB). Total 128 samples including fermented vegetables (60 samples) and fermented fishes (68 samples) were purchased randomly from 5 wet markets in Cambodia from March 2014 to July 2014. In this study, E. coli, Cronobacter sakazakii, shigella spp. Enterobacter spp., other Opportunistic Entrobacteriaceae, Opportunistic Non-Entrobacteriaceae, Vibrio spp., Enterococcus spp., Aerococcus spp., Staphylococcus spp., Listeria spp. and Bacillus cereus were found in both fermented foods. The contamination rates in both categories of fermented foods were different, especially for Enterococcus spp. Coliform bacteria, Enterococcus spp., Staphylococcus spp. and Bacillus cereus in fermented fishes were significantly higher than in those fermented vegetables. Twelve samples (20%) of fermented fishes exceeded the Food Standards Code (FSC) maximum permitted level (200 ppm) for histamine. Enterobacter aerogenes was identified as potential histamine producing bacteria in fermented fishes. Initial pH of fermentation and fast-growing lactic acid bacteria as starter culture play an important role for control histamine producing Enterbacter aerogenes as well as other Enterobacteriaceae. In this case, the combination of initial pH (6.0) with Lactobacillus pentosus or pH (5.0) with Lactococcuslactis ssp. lactis are able to suppress the growth of Enterobacter aerogenes and minimize the content of histamine at below FSC. The results in this works could be information of bacterial contaminants in Cambodian fermented foods that should be prevented and reduced in the future. The quality of the raw material and good hygiene practices in food facility should be required to improve food safety in Cambodia. The strategy of target suitable starter cultures under optimal initial pH of fermentation indicated positive result to reduce poisoning histamine in final fermented foods.