Hygienic level and surface contamination in fresh-cut vegetable production plants

The number of vegetable processing plants has increased during recent years in many countries. At the same time, fresh vegetable products have been implicated by epidemiologic investigations as sources of infection. Fresh vegetables are susceptible to microbial contamination after harvest due to their high water and nutrient contents. Contamination may occur at all stages during production. The aim of this study was to determine the level of surface contamination after cleaning in several fresh-cut vegetable processing plants, and to identify the critical points in the processes and operating rooms. Surface and environmental samples were taken from the plants after cleaning of the processing devices and surfaces. The levels of surface and air hygiene in the vegetable processing factories were determined with different rapid hygiene monitoring methods. The amounts of total aerobic bacteria, Enterobacteriaceae and β-glucuronidase-positive bacteria, yeasts and moulds on surfaces were measured using Hygicult^® contact plates. ATP bioluminescence was measured luminometrically with an HY-LiTE^®2 equipment. The number of microbes in air was measured with an MAS-100 sampler. The highest levels of total aerobic bacteria, yeasts, Enterobacteriaceae and β-glucuronidase-positive bacteria were detected on machines (cutters, peeling machines etc.). High mean values of ATP were detected e.g. on packaging surfaces (due to high values of wooden boxes) and on cutters. Most of the bacterial counts measured on the surfaces were unacceptable when using the Finnish surface hygiene guidelines as criteria. However, the results should be examined in the context of the type of production and the stage of operation also must be taken into account. Different hygiene areas (FDA, 2008) should be separate enough to allow maintenance of good hygiene in cleaner areas while accepting lower hygiene levels e.g. in primary (early) washing steps. Despite this, the results show that there is a clear need to improve cleaning and hygiene practices in vegetable production. Several practical recommendations were given e.g. concerning cleaning, design of production areas, training of employees and self monitoring of surface hygiene. The information obtained will be used for improvement of practices in the cleaning of vegetable processing factories.