Enhanced antimicrobial effects of combination of lactate and diacetate on Listeria monocytogenes and Salmonella spp. in beef bologna.

The antimicrobial activities of salts of organic acids such as lactate and acetate are well documented, but there is limited information on their effect when used in combination. We previously reported enhanced inhibition of Listeria monocvtogenes and Salmonella enterica serovar Enteritidis in sterile comminuted beef at 5 and 10 degrees C by combinations of sodium lactate (SL) (2.5%) and sodium diacetate (SDA) (0.2%). The present study was undertaken to evaluate the inhibitory effect of these salts, alone and in combination, in ready-to-eat (RTE) meat. Single strains and six-strain mixtures of each of the pathogens ( approximately 3 log CFU/g) were tested in beef bologna during aerobic storage at 5 and 10 degrees C for up to 60 days. The growth rate of the six-strain mixture of Listeria was faster than that of the single strain (Scott A) in the lactate/diacetate-free product. While each of the salts delayed growth of the listeriae at 5 degrees C, the effect of their combination was listericidal for the single strain and listeriostatic for the six-strain mixture. Enhanced inhibition by the salt combination was also observed at 10 degrees C. Salmonella numbers declined to undetectable levels in the untreated meat product and in each of the treatments after 20-30 days. However, the decline was more rapid in meat with the combination of the salts during storage at both 5 and 10 degrees C. Each of the salts further delayed the growth of the background microflora during storage at 5 degrees C, with their combinations showing the most effect.