In vitro and in situ growth characteristics and behaviour of spoilage organisms associated with anaerobically stored cooked meat products

AIMS: Understanding spoilage caused by different types of spoilage organisms, associated with vacuum-packaged sliced cooked meat products (CMP). METHODS AND RESULTS: First, strains were characterized in a broth at 7 degrees C under anaerobic conditions to compare their growth rate, acidifying character and metabolite production under conditions simulating refrigerated vacuum-packaged conditions. Brochotrix thermosphacta grew faster than the lactic acid bacteria (LAB). Within the group of the LAB, all strains grew fast except Leuconostoc mesenteroides subsp. dextranicum and Leuconostoc carnosum. Secondly, the organisms were inoculated on a model cooked ham to better understand the relationship between spoilage, microbial growth, pH, metabolite production and accompanying sensory changes. Most rapidly growing strains were Leuc. mesenteroides subsp. mesenteroides followed by B. thermosphacta, while Leuc. mesenteroides subsp. dextranicum and Leuc. carnosum grew very slowly compared with the other LAB. Brochotrix thermosphacta caused sensory deviations at a lower cell number compared with the LAB. The related pH changes, metabolite production and sensory perception are presented. CONCLUSIONS: In this pure culture study, B. thermosphacta and Leuc. mesenteroides subsp. mesenteroides had the highest potential to cause rapid spoilage on CMP. SIGNIFICANCE AND IMPACT OF THE STUDY: A systematic study on the behaviour of spoilage organisms on a model cooked ham to establish the relationship between microbial growth, pH, metabolite formation and organoleptic deviations.