Assessment of Microbial quality of different vegetables in various markets
Comparison of internal and external surface contamination of vegetables
The mean microbial counts of both external and internal parts of the vegetable samples showed overall high contamination for total coliform (TC), faecal coliform (FC) and yeast count (YC). The mean FC levels of all the crops (external and internal surface combined) exceed the International Commission on Microbiological Specifications for Food (ICSMF, 1974) recommended level of 1.0 x 105 fecal coliforms per gram fresh weight. This observation has been reported in Ghana and elsewhere (Obeng, 2007; Mensah et al., 2001). In this study, the contamination of external surface of vegetables was significantly higher than the internal contamination. The total means of the internal microbial counts (TC and FC) of the vegetable samples are high and comparable with counts observed in some non-vegetable foods such as milk and meat (Agbodaze et al. 2005; CDC, 2003; Aning, 2002).
The sources of contamination of vegetables includes Soil, irrigation water, green or inadequately composted manure, air (dust), wild and domestic animals, insects, human handling. harvesting, transporting containers, transporting vehicles, wholesale facilities, washing and rinsing water, improper storage, cross contamination and improper ambient temperature (Beuchat, 1996).

The only non-bacterial quality indicator investigated was yeast contamination, and the levels of yeasts (combined internal and external counts)(table 2a,b;3a,b;4a,b;5a,b) of all the samples were generally higher than the recommended levels of 100 000g -1 fresh weight (ICMSF, 1974). Growth of post-harvest fungi/yeast on vegetables can alter the pH of plant tissues, which promotes the growth of pathogenic bacteria (Anonymous. 1999).
Therefore the high yeast counts could have promoted