Antimicrobial activity of essential oil components against Escherichia coli depends on the food components present in a food matrix

Despite numerous studies evaluating the antimicrobial activity of essential oil components (EOCs) against different microorganisms, the effect of the composition of the matrix in which they are applied remains unexplored. Hence, the effect of different food components (i.e., proteins, lipids, carbohydrates, acids, ethanol) on vanillin antimicrobial activity was carried out by assessing the growth of E. coli at different incubation times (0, 1, 4, 8 and 24 h). Based on these outcomes, the food components that most adversely affected vanillin antimicrobial activity were subsequently tested with four other EOCs (i.e., carvacrol, eugenol, geraniol, thymol). The effective concentration of antimicrobials after coming into contact with food components was quantified. The results indicated that bovine serum albumin (BSA), sunflower oil and carbohydrates partially or completely inhibited the antimicrobial efficacy of the tested EOCs, and the inhibition rate depended on the specific EOC-food component combination. Geraniol was notably the most efficient with BSA present. Eugenol performed best with sunflower oil. Carvacrol, eugenol, geraniol and thymol were more effective than vanillin with D-lactose present. This study confirmed that loss of EOCs' effective concentration due to an interaction with food constituents is a significant cause of antimicrobial activity inhibition. These findings underscore the importance of considering matrix composition when selecting antimicrobials to combat a particular strain in real food applications.