Microbiological quality and incidence of Staphylococcus aureus and Bacillus cereus in vegetarian food products

A total of 320 samples of vegetarian food purchased from local markets were examined in order to determine the microbiological quality of these products. Aerobic count psychrotrophic count, anaerobic count E. Coli, coliforms, S. aureus, B. cereus, spores of Bacillus as well as enterotoxins produced by B. cereus and S. aureus were also evaluated. The incidence of E, coli and coliforms in these vegetarian food products were 28.1% and 32.5%, respectively, while 18.1% and 3.4% of the samples were found to contain S. aureus and B, cereus, respectively. The vegetarian food products investigated in the present study were divided into five groups, based on their major components. The samples made from soybeans showed the highest detection rate (74.5%) when S. aureus, B, cereus, E. coli and coliforms were used as indicators. S. aureus was detected in ail the five groups, with the highest detection rate in cereal and Konjac group (23.8%) while B. cereus was detected only in soybean, cereal and Konjac groups with the incidence of 5.1%, 9.5% and 2.4% respectively. Among the 38 strains of S. aureus isolates, 17 strains were observed to produce enterotoxins of types A, B, C and D. Whereas, among the seven strains of B, cereus isolates, one produced diarrheal toxin while four others killed adult ICR mice. The present results also revealed that vacuum-packed vegetarian foods have the lowest incidence of micro-organisms tested in this study. (C) 1999 Academic Press