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

Abstract

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°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.

Other spoilage bacteria

“…Although B. thermosphacta may not be the most dominant organism, these sensory defects may be observed once this organism has reached 10 5 cfu g -1 (Holley, 2000). Vermeiren et al (2005) found that sensory changes in broth and cooked ham occurred at a lower level of B. thermosphacta than other typical meat spoilage organisms. Brochothrix grew faster than any of the lactic acid bacteria in a broth system, but in a model cooked ham, Leuconostoc mesenteroides grew faster than B. thermosphacta.…”

Prediction of acid lactic-bacteria growth in turkey ham processed by high hydrostatic pressure

“…The recontamination after cooking, especially by the microbiota present in industrial environment is considered as the main factor which affects the shelf life of meat products, along with the storage temperature (Samelis et al , 1998). Typically, the initial count of lactic acid bacteria in meat products packaged under vacuum is low, but increases during refrigerated storage and may cause evident deterioration when the count reaches 7 to 8 log 10 CFU/g (Santos et al , 2005; Vermeiren et al , 2005). …”

Microbial quality and shelf life prediction of vacuum-packaged ready to eat beef rounds containing gum arabic

“…The end of shelf life was taken as the point when the number of lactic acid bacteria exceeded 7 log 10 CFU g −1 according to Kreyenschmidt et al (2010). This is because bacterial growth increases during refrigerated storage, possibly causing evident deterioration when the count reaches 7 to 8 log 10 CFU g −1 (Santos et al, 2005;Vermeiren, Devlieghere, De Graef, & Debevere, 2005). The Baranyi and modified Gompertz models were used in primary modelling to fit the TVC and LAB data obtained using CompBase, DMFit version 3.5 (Institute of Food Research, Norwich, UK, http://www.…”