Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/1/2006
Publication Date: 1/1/2007
Citation: Juneja, V.K., Friedman, M. 2007. Carvacrol, cinnamaldehyde, oregano oil, and thymol inhibit clostridium perfringens spore germination and outgrowth in ground turkey during chilling. Journal of Food Protection. 70:218-222. Interpretive Summary: One of the most common types of food poisoning in the United States is caused by the bacterium, Clostridium perfringens. Illnesses have been traditionally associated with inadequate cooling practices in retail food service operations. Thus, there was a need to determine the cooling time and temperature for cooked meat products to remain pathogen-free and provide vital data for performing risk assessment on cooked meat. We determined that cooling times for ground turkey after heat processing can be extended to 21 h by incorporation of the antimicrobial ingredients, carvacrol, cinnamaldehyde, thymol, and oregano oil, at more than or equal to 0.5% level to reduce the potential risk of C. perfringens germination and outgrowth. These findings will be of immediate use to the retail food service operations and regulatory agencies to ensure the safety of the cooked foods.
Technical Abstract: Inhibition of Clostridium perfringens by plant-derived carvacrol, cinnamaldehyde, thymol, and oregano oil was evaluated during abusive chilling of cooked ground turkey (75% lean) obtained from a local grocery store. Test substances were mixed into thawed turkey product at concentrations of 0.1, 0.5, 1.0 or 2.0% (w/w) along with a heat-activated three-strain C.perfringens spore cocktail to obtain final spore concentrations of ca. 2.2-2.8 log10 CFU spores/g of turkey meat. Aliquots (5 g) of the ground turkey mixtures were vacuum-packaged and then cooked in a water bath, where in temperature was raised to 60 degree C in 1 h. The products were cooled from 54.4 degree C to 7.2 degree C in 12, 15, 18 or 21 h, resulting in 2.9, 5.5, 4.9 and 4.2 log10 CFU/g increases, respectively, in C. perfringens populations in samples without antimicrobials. Incorporation of test compounds (0.1% to 0.5%) into the turkey completely inhibited C. perfringens spore germination and outgrowth (p less than or equal to 0.05) during exponential cooling in 12 h. Longer chilling times (15, 18 and 21 h) required greater concentrations (0.5% to 2.0%) to inhibit spore germination and outgrowth. Cinnamaldehyde was significantly (p less than or equal to 0.05) more effective (less than 1.0 log CFU/g growth) than the other compounds at a lower concentration (0.5%) at the most abusive chilling rate evaluated (21 h). These findings establish the value of the plant-derived antimicrobials for inhibiting C. perfringens in commercial ground turkey products.