The Effect of Different Packaging Conditions, pH and Lactobacillus spp. on the Growth of Yersinia enterocolitica in Pork Meat

The growth of Yersinia enterocolitica and lactic acid bacteria in minced pork meat stored at 4C under vacuum and modified atmosphere packaging (MAP) was determined. In addition, the influence of different pH values and total volatile basic nitrogen (TVB-N) on the growth of Y. enterocolitica was evaluated. Ground meat was packed under customary conditions using vacuum and modified atmospheres with different CO2 concentrations (MAP 1 was 20% O2, 50% CO2 and 30% N2; MAP 2 was 20% O2, 30% CO2 and 50% N2) and stored at 4 ± 1C for 12 days. During the storage time, Y. enterocolitica counts were determined by direct plate counts. Y. enterocolitica counts in pork were not significantly different (P > 0.01; P > 0.05) under the two packaging conditions, but were significantly different (P < 0.01; P < 0.05) between storage days in the same packs. Packaging with higher CO2 concentration had an inhibitory effect on the growth of Y. enterocolitica. Practical Applications Several preservation techniques are used to extend the shelf life of meat and meat products. Packaging of fresh meat is a common application to protect meat quality. Modified atmosphere packaging (MAP) involves replacement of air in a package of food with different mixture of gases. For proper MAP application and for preserving meat quality, it is crucial to choose a suitable combination of gas, packaging system, packaging application and packaging material. A specific gas combination to ensure meat quality should be used. Several studies have been performed to study the extension of fresh pork meat shelf life using MAP techniques. However, there are few data on the behavior of Yersinia enterocolitica in pork meat under MAP. The results of this research will form the basis for further studies and will also be beneficial for the meat industry.