Use of rRNA gene restriction patterns to evaluate lactic acid bacterium contamination of vacuum-packaged sliced cooked whole-meat product in a meat processing plant

Abstract

Molecular typing was applied to an in-plant lactic acid bacterium (LAB) contamination analysis of a vacuum-packaged sliced cooked whole-meat product. A total of 982 LAB isolates from the raw mass, product, and the environment at different production stages were screened by restriction endonuclease (EcoRI and HindIII) analysis. rRNA gene restriction patterns were further determined for different strains obtained from each source. These patterns were used for recognizing the spoilage-causing LAB strains from the product on the sell-by day and tracing the sources and sites of spoilage LAB contamination during the manufacture. LAB typing resulted in 71 different ribotypes, of which 27 were associated with contamination routes. Raw material was distinguished as the source of the major spoilage strains. Contamination of the product surfaces after cooking was shown to be airborne. The removal of the product from the cooking forms was localized as a major site of airborne LAB contamination. Food handlers and some surfaces in contact with the product during the manufacture were also contaminated with the spoilage strains. Some LAB strains were also able to resist cooking in the core of the product bar. These strains may have an effect on the product shelf life by contaminating the slicing machine. The air in the slicing department and adjacent cold room contained very few LAB. Surface-mediated contamination was detected during the slicing and packaging stages. Food handlers also carried strains later found in the packaged product. Molecular typing provided useful information revealing the LAB contamination sources and sites of this product. The production line will be reorganized in accordance with these results to reduce spoilage LAB contamination.

Molecular methods for the analysis of Clostridium perfringens relevant to food hygiene

“…Ribotyping was performed according to the method described by Grimont and Grimont [21]. DNA was isolated using the guanidinium thiocyanate method of Pitcher et al [22] with modi¢cations [12]. Ensuing procedures were carried out as described previously [23].…”

Identification and Characterization of Leuconostoc carnosum , Associated with Production and Spoilage of Vacuum-Packaged, Sliced, Cooked Ham

“…In an LAB contamination study of vacuum-packaged, sliced, cooked ham, 982 LAB isolates from the spoiled product and production line were characterized in order to determine the underlying reasons for fluctuations in product quality (4,6). Many lots had been showing spoilage changes, i.e., sour odor and taste, before the sell-by date.…”

Carnobacterium divergens - a dominating bacterium of pork meat juice

“…and Leuconostoc spp. in spoiled meat products (Borch et al, 1996;Bjorkroth & Korkeala, 1997;Bjorkroth et al, 2000;Santos et al, 2005;Chenoll et al, 2007), indicating an overgrowth of the fresh meat dominating Carnobacterium spp. by other LAB during storage (Jones, 2004;Chenoll et al, 2007).…”