Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2006
Publication Date: 1/1/2007
Citation: Juneja, V.K., Thippareddi, T.H., Bari, L., Inatsu, Y., Kawamoto, S., Friedman, M. 2007. Chitosan protects cooked ground beef and turkey against clostridium perfringens spores during chilling. Journal of Food Science. Vol. 71(6):M236-M240. 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 beef and turkey products to remain pathogen-free and provide vital data for performing risk assessment on cooked meat. We determined that cooling times for ground beef and turkey after heat processing can be extended to 18 h by incorporation of chitosan at 3% 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: We investigated the inhibition of Clostridium perfringens spore germination and outgrowth by the biopolymer chitosan during abusive chilling of cooked ground beef (25% fat) and turkey (7% fat) obtained from a retail store. Chitosan was mixed into the thawed beef or turkey at concentrations of 0.5, 1.0, 2.0, or 3.0% (w/w) along with a heat-activated three-strain spore cocktail to obtain a final spore concentration of 2 to 3 log10 CFU/g. Samples (5 gm) of the ground beef or turkey mixtures were then vacuum-packaged and cooked to 60 deg C in one hour in a temperature-controlled water bath. Thereafter, the products were cooled from 54.4 deg C to 7.2 deg C in 12, 15, 18 or 21 h, resulting in 4.21, 4.51, 5.03, and 4.70 log10 CFU/g increases, respectively, in C. perfringens populations in the ground beef control samples without chitosan. The corresponding increases for ground turkey were 5.27, 4.52, 5.11, and 5.38 log10 CFU/g. Addition of chitosan to beef or turkey resulted in concentration- and time-dependent decreases in the spore counts. At 3%, chitosan reduced by 4 to 5 log10 CFU/g C. perfringens spore germination and outgrowth (p < 0.05) during exponential cooling of the cooked beef or turkey in 12, 15, or 18 h. The reduction was significantly lower (p < 0.05) at a chilling time of 21 h, about 2 log10 CFU/g (7.56 log10 CFU/g; unsupplemented versus 5.59 log10 CFU/g; 3% chitosan). The results suggest that incorporation of 3% chitosan into ground beef or turkey may reduce the potential risk of C. perfringens spore germination and outgrowth during abusive cooling from 54.4 deg C to 7.2 deg C in 12, 15 or 18 h.