Microbiological quality of local dehydrated soups with special reference to Bacillus cereus

ABSTRACT

A total of 105 samples of precooked dehydrated soups representing the different types produced in Egypt were examined. Moisture content ranged from 1.5 to 6% and pH values were between 6.9 and 7.7. Mean values of total bacterial counts were generally less than 105 CFU/g except for brand "F" which contained about 103 CFU/g. Wide variation in the percentage of sporeformers in total count was observed. Mean values of spore counts ranged from 103 to 104 CFU/g. Bacillus cereus was found in variable densities; mean values hardly exceeding 104/g, it was not detected in some samples. Generally, B. Cereus represented 20-70% of the total spore counts. Yeast colony mean counts around 102 CFU/g. Enterobacteriaceae, molds coliforms, Staphylococcus aureus, Streptococcus faecalis and salmonellae could not be detected in all samples. D10 value of B. cereus was 2.85 KGy, while the D10 values at 85, 90, 95 and 100C were found to be 15.0, 9.5, 8.5 and 2.5 min, respectively. Preirradiation treatment of B. cereus spores had a synergistic effect with heat treatment