Inhibitory effect of thyme and cinnamon essential oils against e. Coli o157:H7 in tahini

Abstract

Tahini is a common food product in the Mediterranean area that is used as a main ingredient in variety of ready-to-eat foods. The objective of the current study was to investigate the inhibitory effect of thyme oil (TO) or cinnamon oil (CO) on E. coli O157:H7 viability in tahini and diluted tahini at different storage temperatures. Addition of 2.0% CO to tahini reduced E. coli O157:H7 numbers by 1.38, 1.79 or 2.20 log10 CFU/mL at 10, 25 or 37 °C, respectively, by 28d. In diluted tahini at 10 °C, no viable cells of E. coli O157:H7 by 21d were detected when 1.0% CO was used. However, at 25 and 37 °C, no viable cells were detected by 14d when CO was added at 0.5% level. Addition of 2.0% TO to tahini, resulted in 1.82, 2.01 or 1.65 log10 CFU/mL reduction in E. coli O 157:H7 numbers was noted at 37, 25 or 10 °C, respectively, by 28d. In diluted tahini, TO at 0.5% or 1.0% induced complete reduction in the viability of E. coli O157:H7 by 28d storage at 37 or 25 °C. At 10 °C, a 3.02 log10 CFU/mL reduction was observed by 28d compared to the initial inoculation level in samples treated with 2.0% TO.