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Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/28/2005 Publication Date: 6/1/2006 Citation: Juneja, V.K. 2006. Delayed clostridium perfringens growth from a spore inocula by sodium lactate in sous-vide chicken products. Food Microbiology. 23:105-111. Interpretive Summary: Commercial application of sous-vide technology, the cooking of food in a vacuum bag, has been limited. Concerns have been expressed about the public-health risks associated with sous-vide processed foods because the mild heat treatment required to retain the sensory attributes may not ensure proper destruction of pathogenic and spoilage organisms. The safety of sous-vide foods cannot be considered to rely on only one single 'chilled storage' factor. Since one of the most common types of food poisoning in the United States is caused by the bacterium, Clostridium perfringens, there was a need to determine the fate of the pathogen in sous-vide processed foods. We determined that marinated chicken breast meat supplemented with 1.5% sodium lactate can provide an extra degree of safety in temperature-abused products. These findings will be of immediate use to the retail food service operations and regulatory agencies to ensure the safety of the sous-vide foods. Technical Abstract: Clostridium perfringens growth from a spore inoculum was investigated in vacuum packaged, cook-in-bag marinated chicken 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 various temperatures. 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, an 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. 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 less than or equal to 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. |
