Effect of L-glucose and D-tagatose on bacterial growth in media and a cooked cured ham product

Cured meats such as ham can undergo premature spoilage on account of the pr oliferation of lactic acid bacteria. This spoilage is generally evident fro m a milkiness in the purge of vacuum-packaged sliced ham. Although cured, m ost hams are at more risk of spoilage than other types of processed meat pr oducts because they contain considerably higher concentrations of carbohydr ates, similar to 2 to 7%, usually in the form of dextrose and corn syrup so lids. Unfortunately, the meat industry is restricted with respect to the ch oice of preservatives and bactericidal agents. An alternative approach from these chemical compounds would be to use novel carbohydrate sources that a re unrecognizable to spoilage bacteria. L-Glucose and D-tagatose are two su ch potential sugars, and in a series of tests in vitro, the ability of bact eria 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 cataboliz ed by a variety of lactic bacteria and not at all by pathogenic bacteria su ch as Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aure us, Bacillus cereus, and Yersinia enterocolitica. In a separate study, D-gl ucose, L-glucose, and D-tagatose were added to a chopped and formed ham for mulation and the rate of bacterial growth was monitored. Analysis of data b y a general linear model revealed that the growth rates of total aerobic an d lactic acid bacteria were significantly (P < 0.05) slower for the formula tion containing D-tagatose than those containing L- or D-glucose. Levels of Enterobacteriaceae were initially low and these bacteria did not significa ntly (P < 0.20) change in the presence of any of the sugars used in the mea t formulations. Compared to the control sample containing D-glucose, the sh elf life of the chopped and formed ham containing D-tagatose at 10 degrees C was extended by 7 to 10 days. These results indicate that D-tagatose coul d deter the growth of microorganisms and inhibit the rate of spoilage in a meat product containing carbohydrates.