Bacterial Contamination and Microflora of Several Fresh Produce

Abstract

Consumption of fresh produce has increased, mainly because of heightened awareness of the benefits of a healthy diet. Leafy or salad vegetables are mainly eaten fresh and have become increasingly popular because of their high sensory quality and convenience (Lund, 1989). These vegetables are high in water, vitamins, minerals, and dietary fiber (Weerakkody, 2003). Minimal processing to which fresh produce is subjected renders vegetables to physiological deterioration, biochemical changes and microbial degradation of product (O’Beirne and Francis, 2003). Additionally, cut tissues release nutrients that support the growth of microflora present on raw produce (Li et al., 2001). Ready–to–use vegetables harbor large and diverse populations of microorganisms, and counts of 5.0–7.0 log cfu/g are frequently present. Eighty to ninety percent of bacteria are Gram–negative rods, predominantly Pseudomonas, Enterobacter or Erwinia species as reviewed by Francis et al. (1999). Fresh–cut vegetables retain much of their indigenous microflora after minimal processing, however, pathogens may form part of this microflora, posing a potential food safety problem (Francis, et al., 1999). Surveys of bagged salads often recover low numbers of enteropathogens (Szabo et al., 2000; Francis et al., 1999; Lin et al., 1996). According to the study of the disease risks of food groups by Adak et al. (2005), a low risk ratio for salad vegetables was reported even though fresh produce has a considerable impact on disease incidence in a population. A factor that impacts microbial quality is the increase in importation, which aims to meet consumer demands for a wide choice of exotic fruit and vegetables year–round. As hygiene standards of irrigation, at harvest, and during storage can vary widely in different countries, the potential for contamination of produce may increase. The objectives of this study are to determine the viable counts and the regions of natural bacterial contamination in various vegetables, and identify the microflora of celery, lettuce, parsley, radish, and radish sprouts that are distributed in Fukuoka area, using biochemical methods.