The real role of select herb and spice extracts against Bacillus cereus ATCC 14579 growth in cooked rice

Abstract

This study aimed to investigate the effect of select spices and herbs added to cooked rice in the growth of Bacillus cereus. The results showed the actual role of herbs and spices as food flavoring ingredients rather than acting as a preservative agent. Herbs and spices extracts were added to rice before and after the cooking process, then observed the differences in Bacillus cereus growth. From all herb and spices extract used, clove was the most effective one against B. cereus. It provided a good zone of inhibition, while the others did not have similar effects. The ethanolic extracts for all tested herbs and spices at concentrations of 50-200 µg/mL showed good activity in media. The zone of inhibition was from 10 to 25 mm in diameter. Rice with Spiced/herbs was inoculated with 10⁸ spores of B. cereus then the growth of B. cereus vegetative cells was detected at different temperature. As the result showed no different in the growth of B. cereus, We concluded that the temperature for rice cooking/reheating has main effect on the control of B. cereus cells while herbs and spices can be used only for flavor with no role in controlling the contamination in rice.

Keywords:
herbs; spices; Bacillus cereus; cooked rice