Antimicrobial activity of carvacrol toward Bacillus cereus on rice

The antimicrobial activity of carvacrol, a compound present in the essentia l oil fraction of oreganum and thyme, toward the foodborne pathogen Bacillu s cereus on rice was studied. Carvacrol showed a dose-related inhibition of growth of the pathogen. Concentrations of 0.15 mg/g and higher inhibited t he growth and the extent of inhibition depended on the initial inoculum siz e. To decrease the input of carvacrol on the taste and flavor of the produc t, a combined treatment with the structure analog cymene was tested. Due to the smell and taste of carvacrol at high concentrations, carvacrol was com bined with cymene, a natural antimicrobial compound with a similar structur e. A synergistic effect was observed when 0.30 mg/g carvacrol was combined with 0.27 mg/g cymene. Finally it was demonstrated that a common taste enha ncer like soya sauce also increased the antimicrobial action of carvacrol t oward B. cereus. The antimicrobial activity of carvacrol with cymene or soy a sauce was influenced by the addition of NaCl.