engleski

Survival and growth of Listeria monocytogenes in ready-to-eat vegetables

Introduction Listeria monocytogenes is important for its resistance and ability to colonize, survive and grow at refrigeration temperatures. Incidence of listeriosis depends on amount of bacterium consumed. The aim of research was to investigate survival and growth of L. monocytogenes on ready-to-eat vegetables. Material and Methods Fifty samples of lettuce, cabbage and delicate salads, mixed and rooty ready-to-eat vegetables were inoculated with referral strain of L. monocytogenes ATCC 35152. Survival and growth were investigated during shelf life and storage at refrigeration temperature using following methods: HRN EN ISO 11290-1 Horizontal method for the detection end enumeration of Listeria monocytogenes - Part 1: Detection method (ISO 11290-1: 1996 ; EN ISO 11290-1: 1996) and HRN EN ISO 11290-2 Horizontal method for the detection end enumeration of Listeria monocytogenes - Part 2: Enumeration method (ISO 11290-2: 1998 ; EN ISO 11290-2: 1998). Results Survival of inoculated strain was determined in all groups of investigated vegetables. Incomplete inhibition of bacterial growth was determined in inoculated mixed vegetables, while complete inhibition of bacterial growth was determined in rooty vegetables. Population growth was weak in all inoculated samples stored at adequate refrigeration temperature. Conclusions The research confirmed that this kind of ready-to-eat food can be considered a potential source of L. monocytogenes infection and that different vegetables have different potential for support of L. monocytogenes growth. Results indicated that temperature level was the most important factor for control of the bacterial growth, so it is necessary to maintain cold chain continuity. Results also show the need for monitoring L. monocytogenes presence in production, storage and sale, in order to minimize its potential presence at the moment of consummation in amounts harmful for people’s health. Further research of survival and growth of L. monocytogenes in production environment and in different combinations of vegetables are necessary in order to ensure microbiological safety for the consumers.

Listeria monocytogenes; ready-to-eat vegetables

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