Inhibition of nonproteolytic, psychrotrophic clostridia and anaerobic sporeformers by sodium diacetate and sodium lactate in cook-in-bag turkey breast

A nonproteolytic, psychrotrophic Clostridium isolate, designated strain OMFRI1, was recovered from cook-in-bag turkey breasts (CIBTB) that displayed an intense pink discoloration and an off-odor following extended refrigerated storage. The viability of strain OMFRI1 in CIBTB containing sodium diacetate (at 0, 0.25, and 0.5%) and/or sodium lactate (at 0, 1.25, and 2.5%) was subsequently evaluated. Raw CIBTB batter was inoculated with 9 to 30 spores of strain OMFRI1 per g, vacuum packaged, cooked to an instantaneous internal temperature of 71.1degreesC, chilled, and incubated at 4degreesC for up to 22 weeks. In the absence of food-grade antimicrobial agents, spoilage (i.e., an off-odor) occurred within 6 weeks, and anaerobic plate counts reached 6.6 log(10) CFU/g. The CIBTB containing sodium diacetate (0.25%) and that containing sodium lactate (1.25%) required 12 weeks for spoilage to occur and for anaerobic plate counts to reach 7.0 and 6.0 log(10) CFU/g, respectively. When sodium diacetate (0.25%) and sodium lactate (1.25%) were used in combination, no off-odor was detected and anaerobic plate counts did not exceed 2.3 log(10) CFU/g over 22 weeks of storage at 4degreesC. In related experiments, sodium diacetate (at 0, 0.25, and 0.5%), sodium lactate (at 0, 1.25, and 2.5%), and combinations of both ingredients were evaluated in uninoculated CIBTB incubated at 25degreesC for up to 22 days. In the absence of antimicrobial agents and in CIBTB containing sodium diacetate (0.5%), spoilage occurred within 8 days and anaerobic plate counts reached 6.8 and 6.6 log(10) CFU/g, respectively. Samples of CIBTB containing sodium lactate (2.5%) showed signs of spoilage within 22 days, and anaerobic plate counts for these samples ranged from less than or equal to1.0 to 6.3 log(10) CFU/g. In CIBTB containing both sodium lactate (2.5%) and sodium diacetate (0.25%), spoilage was not evident and anaerobic plate counts were less than or equal to1.0 log(10) CFU/g within 22 days. These data validate the efficacy of sodium lactate and sodium diacetate in extending the shelf life of CIBTB.