Delayed Clostridium perfringens growth from a spore inocula by sodium lactate in sous-vide chicken products Original Research Article

Clostridium perfringens growth from a spore inoculum was investigated in vacuum-packaged, cook-in-bag marinated chicken breast that included 0%, 1.5%, 3%, or 4.8% sodium lactate (NaL; w/w). The packages were processed to an internal temperature of 71.1 °C, ice chilled and stored at 4, 19, and 25 °C. The total C. perfringens population was determined by plating diluted samples on Tryptose–sulfite–cycloserine agar followed by anaerobic incubation for 48 h at 37 °C. At 25 °C, addition of 1.5% NaL was effective in delaying growth for 29 h. Increasing the NaL level to 4.8%, C. perfringens growth from a spore inoculum during storage at 25 °C for 480 h was not observed. At 19 °C, the growth was >6 log10 cfu/g by 288 h in control samples. In samples with 3.0% or 4.8% NaL, the growth of C. perfringens from spores was dramatically restricted with little or no growth in 648 h at 19 °C. C. perfringens growth was not observed at 4 °C regardless of NaL concentration. The D-values at 55 °C ranged from 47.40 (no NaL) to 57.58 min (1.5% NaL). Cyclic and static temperature abuse of refrigerated products for ⩽20 h did not permit C. perfringens growth. However, temperature abuse of products for periods 24 h or longer in the absence of NaL led to growth of C. perfringens from a spore inoculum. An extra degree of safety may be assured in such products by supplementation with NaL at 1.5–4.8% NaL level.