Fat content and storage conditions are key factors on the partitioning and activity of carvacrol in antimicrobial packaging

The ability of carvacrol loaded polylactic acid (PLA) films to improve ground beef preservation was assessed. The mass transfer processes of carvacrol partitioning in a food packaging system between the PLA film, headspace and food product was studied. Carvacrol release was studied on packed ground beef having a fat content of 5 or 12 % at a temperature between 5 and 30 °C and a humidity between 43 and 94 % for up to 12 days. Results showed the release rate of carvacrol from the PLA film into the headspace increased with the storage temperature while the humidity in the packaging headspace had no effect on the release rate of carvacrol from the PLA film. The fat content of ground beef has a profound effect on the partitioning of carvacrol: when the system is stored at 5 °C the carvacrol absorption in the 12 % fat ground beef was about 1.3-fold compared with the carvacrol concentration observed in 5% fat ground beef. Despite this higher carvacrol absorption in the regular beef, the PLA/carvacrol films had a stronger antimicrobial effect on the lean beef suggesting that partitioning of carvacrol into the fat phase of the beef reduced its antimicrobial activity. Results highlight the importance of considering the food matrix composition in the design of antimicrobial packaging based on natural volatile components.