Inhibition of toxicogenic Bacillus cereus in rice-based foods by enterocin AS-48

The antimicrobial effect of the broad-spectrum bacteriocin enterocin AS-48 against the toxicogenic psychrotrophic strain Bacillus cereus LWL1 has been investigated in a model food system consisting of boiled rice and in a commercial infant rice-based gruel dissolved in whole milk stored at temperatures of 37 °C, 15 °C and 6 °C. In food samples supplemented with enterocin AS-48 (in a concentration range of 20–35 μg/ml), viable cell counts decreased rapidly over incubation time, depending on the bacteriocin concentration, the temperature of incubation and the food sample. Enterotoxin production at 37 °C was also inhibited. Heat sensitivity of endospores increased markedly in food samples supplemented with enterocin AS-48: inactivation of endospores was achieved by heating for 1 min at 90 °C in boiled rice or at 95 °C in rice-based gruel. Activity of enterocin AS-48 in rice gruel was potentiated by sodium lactate in a concentration-dependent way.