Lactic acid bacteria and their influence on the shelf life of heat-treated meat products

The aim of the study was to analyse lactic acid bacteria (LAB) in frankfurters with a finely comminuted batter after their packaging in a modified atmosphere (N2/CO2: 70/30) and subsequent storage for 21 days at 2 °C. Microbiological tests of the production plant environment for the presence of LAB and potential product contamination were also performed. Species determination of isolated bacterial strains was performed by the MALDI-TOF MS method. LAB could not be isolated either from the surface or from the product immediately after packaging. The growth of LAB did, however, occur during two weeks of storage. After 21 days the population of LAB exceeded values of 106 colony-forming units (CFU) cm-2 on the surface of the product and 5 x 105 CFU.g-1 in the product. The species Leuconostoc carnosum, Lactococcus lactis and Lactobacillus curvatus were isolated from the product surface, and the species Lactococcus garviae, Leuconostoc carnosum and Pediococcus pentosaceus from frankfurters after three weeks. The results of swabs from the environment indicated a source of product contamination by LAB. Eleven species of LAB were isolated from the working environment.