Antimicrobial activity of cell-free supernatant of lactic acid bacteria on spoilage bacteria of vacuum-packed sliced emulsion-type sausages.

Background: Spoilage is very common in vacuum-packed sliced emulsion-type sausages during refrigerated storage. Aims: This study aimed to investigate the inhibitory effects of cell-free supernatant (CFS) of lactic acid bacteria (LAB) on the spoilage bacteria isolated from vacuum-packed sliced emulsion-type sausages as biological preservatives.

Methods: These products from various companies were examined to find the spoilage bacteria. A total of 43 LABs were screened for inhibitory activity against the spoilage bacteria. The MIC₉₀ of protective bacteria and the inhibitory effect of different components obtained from these bacteria was investigated.

Results: Four LAB were confirmed as the predominant spoilage bacteria, including Enterococcus mundtii, Latilactobacillus sakei, Latilactobacillus curvatus, and Weissella viridescens. Six strains, including Lactobacillus acidophilus ATCC 4356, Lactobacillus helveticus PTCC 1332, Lactiplantibacillus plantarum CEC 17484, Lactiplantibacillus plantarum LL441, Lacticaseibacillus rhamnosus ATCC 53103, and Pediococcus acidilactici DSM 20284 were able to produce proteinaceous antimicrobial metabolites against the four spoilage agents, which were selected as protective bacteria. CFS of the protective bacteria inhibited four spoilage bacteria by more than 88%. The MIC₉₀ of all protective bacteria was less than 10 mg/ml against E. mundtii and L. sakei. After neutralizing acid and H₂O₂ of the CFS of P. acidilactici, it was still quite effective against E. mundtii and L. sakei. The sausage's pasteurization temperature did not affect the bacteria's active metabolites.

Conclusion: The substances derived from these bacteria can be applied as biopreservatives in sliced sausage, even in the pre-pasteurization stage of these products.