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The meat industry is in need of faster and more reliable methods to determine microbial loads in food products. A rapid method (<15 min) has been developed to assess the microbiological quality of chicken carcasses using the adenosine triphosphate (ATP) bioluminescence assay. The results indicate that, following modifications, the ATP bioluminescence test produced an acceptable correlation with plate counts (r = 0.85, p < 0.001) and demonstrated good repeatability between replicates. It is envisaged that the modified ATP bioluminescence assay would best be used as a platform rejection test. Using threshold levels determined from the regression equation, the ATP bioluminescence assays gave about 90% agreement with plate counts for carcass rinses with counts above 5 × 104 CFU/ml. These findings suggest that the modified ATP bioluminescence assay could be used for monitoring critical control points (CCPs) in programs based on hazard analysis of critical control points (HACCP).

Cured meats such as ham can undergo premature spoilage on account of the proliferation of lactic acid bacteria. This spoilage is generally evident from a milkiness in the purge of vacuum-packaged sliced ham. Although cured, most hams are at more risk of spoilage than other types of processed meat products because they contain considerably higher concentrations of carbohydrates, ∼2 to 7%, usually in the form of dextrose and corn syrup solids. Unfortunately, the meat industry is restricted with respect to the choice of preservatives and bactericidal agents. An alternative approach from these chemical compounds would be to use novel carbohydrate sources that are unrecognizable to spoilage bacteria. l-Glucose and d-tagatose are two such potential sugars, and in a series of tests in vitro, the ability of bacteria to utilize each as an energy source was compared to that of d-glucose. Results showed that both l-glucose and d-tagatose are not easily catabolized by a variety of lactic bacteria and not at all by pathogenic bacteria such as Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus, and Yersinia enterocolitica. In a separate study, d-glucose, l-glucose, and d-tagatose were added to a chopped and formed ham formulation and the rate of bacterial growth was monitored. Analysis of data by a general linear model revealed that the growth rates of total aerobic and lactic acid bacteria were significantly (P < 0.05) slower for the formulation containing d-tagatose than those containing l-or d-glucose. Levels of Enterobacteriaceae were initially low and these bacteria did not significantly (P < 0.20) change in the presence of any of the sugars used in the meat formulations. Compared to the control sample containing d-glucose, the shelf life of the chopped and formed ham containing d-tagatose at 10°C was extended by 7 to 10 days. These results indicate that d-tagatose could deter the growth of microorganisms and inhibit the rate of spoilage in a meat product containing carbohydrates.

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To determine the long-term effects of a lactic acid rinse on viability and recovery of pathogens, Salmonella Hadar was isolated from poultry and bioluminescent constructs obtained by transformation with the lux (CDABE) gene cassette from Photobacterium phosphoreum. Results indicated that the transformed Salmonella Hadar lux was otherwise phenotypically similar to the wild-type strain. Viability studies were performed by measuring luminescence following lactic acid treatment of turkey breast and subsequent storage at -12, 0, 5, and 10 degrees C. The ability of the S. Hadar lux strain to recover was determined by monitoring light output after incubation at 22 degrees C for 10 h. The results showed that metabolic activity was significantly (P < 0.05) affected by lactic acid and by storage temperatures of -12, 0, and 5 degrees C. The lowest recovery rate was observed after rinsing with lactic acid and storing at 5 degrees C. The study demonstrated that bacterial bioluminescence is an effective way of monitoring in "real time" the ability of bacteria to recover from stress.