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

Abstract

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 71.1°C, chilled, and incubated at 4°C 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 log10 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 log10 CFU/g over 22 weeks of storage at 4°C. 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 25°C 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 ≤1.0 to 6.3 log10 CFU/g. In CIBTB containing both sodium lactate (2.5%) and sodium diacetate (0.25%), spoilage was not evident and anaerobic plate counts were ≤1.0 log10 CFU/g within 22 days. These data validate the efficacy of sodium lactate and sodium diacetate in extending the shelf life of CIBTB.