Microbial hazards related to rice sprouting

The microbiology of rice seeds selected for commercial production of sprouts was studied. Bacteria were numerous but generally nonpathogenic: almost all were gram-negative rods, predominantly pseudomonads. There were also several enterobacteria, in particular Enterobacter and Klebsiella species. Escherichia coli was present in very few samples and its serotype was not enteropathogenic. Moulds were infrequent. Storage of seeds under laboratory conditions did not greatly modify the composition of the microflora but counts decreased with time. When grains were stored in a cold room, the microflora remained almost unchanged quantitatively and qualitatively. After 2 days of germination, mesophilic aerobic plate counts increased by about 2 log cycles; thermotolerant coliforms and faecal enterococci increased by up to 6 log cycles. No foodborne pathogens were detected on sprouts. Moreover, both dry seeds and sprouts were negative for aflatoxins. Experiments with artificially inoculated seeds showed that Bacillus cereus and Listeria sp. could develop without any antagonistic effect from the background flora of germinating rice.