Abstract
The close button and open cup mushrooms of Agaricus bisporus were examined respectively for the coliform as well as total viable counts. The different parts: skin, stem (stipe) and internal gills were also examined and compared. The highest total viable counts of 1.32 x 108 cfu/g was obtained from the skins while the lowest counts of 3.01 x 106 cfu/g came from the internal gills. The effect of washing before treatment was examined and it was observed to be effective in reducing the microbial loads in both samples. When some of the microorganisms were isolated and stained, a high percentage was observed to be Gram positive. The catalase positive microorganisms were observed to dominate the microflora. Blanching at different temperatures was also carried out to know the effects on weight loss and microbial loads of the mushrooms. Weight loss was observed to be higher in the open cup mushrooms than the close button ones. However, the microbial loads reduced greatly in both samples when blanched.