Effects of bacterial strains on the development of the ripening flavor of cured pork loins

To determine the effect of bacteria on the development of the ripening flavor of cured meat, pork loins were cured with pickles containing 8 or 16% sodium chloride at 0 and 8 deg C. The bacterial flora, total free amino acid content and total free fatty acid content in the cured loins, sensory properties of cooked pork loins and the relationships between the proteolytic and lipolytic activities of isolates and curing conditions were investigated. Desirable bacteria, including salt-tolerant bacteria and lactic acid bacteria, were predominant under the condition of 8% sodium chloride in the pickles and a curing temperature of 8 deg C. The total free amino acid content and total free fatty acid content at a curing temperature of 8 deg C were higher than those at 0 deg C. Cooked pork loins cured in pickles containing 8% sodium chloride at a temperature of 8 deg C for more than 7 days were preferred in terms of color, flavor and taste. Before the curing procedure, gram-negative bacteria (Vibrio, Acinetobacter, Pseudomonas and Enterobacteriaceae) were predominant in the pork loins. During the curing period, the numbers of viable gram-positive bacteria (Micrococcus, Staphylococcus and Pediococcus) increased and the numbers of viable gram-negative bacteria decreased. Strains of Micrococcus and Staphylococcus with proteolytic and/or lipolytic activities in cured meat also increased during the curing period and were more predominant in the pork loins cured in pickles containing 8% sodium chloride and at a curing temperature of 8 deg C than in pork loins cured in pickles containing 16% sodium chloride and at a curing temperature of 0 deg C. The actions of these bacteria were thought to be important factors affecting the flavor of the cured pork. Micrococcus and Staphylococcus with proteolytic activity might contribute to the development of the ripening flavor of ham. The results of the present study together with the results of further investigations on the relationships of the enzyme activities of Micrococcus and Staphylococcus in cured meat with a preferable flavor would be useful for establishing a novel effective method for using bacteria to produce ham of a high quality.