The objective of the present study was to evaluate the effect of modified atmospheres on refrigerated pork meat (Longissimus dorsi). Pork meat was cut into ca. 1cm thick slices of 9cm², introduced in Cryovac type BB4L bags, characterized by its low gas permeability, and divided into four batches. The bags of each batch were filled with either 1.0 L of air (100%), nitrogen (100%), 20/80 or 40/60 CO2/O2 and finally sealed. Samples were subdivided into two batches and stored in walk-in cold rooms at 1 and 7ºC. Samples were taken at different days of storage and pH and gas concentration (CO2/O2/N2) were determined. Likewise, total viable, lactic acid bacteria, Enterobacteriaceae, Brochothrix thermosphacta and Pseudomonas were counted. Bacterial growth parameters were assessed using Gompertz equations. As expected, modified atmosphere packaging extended the pork meat shelf life. However, modified atmospheres enriched with CO2 and at 1ºC showed a greater effectiveness. The samples conserved in MAP enriched in CO2, as much to 7 as to 1ºC, maintained the constant pH during the period of storage. At 1 and 7ºC the lag phases and the duplication times of the total microbiota were progressively larger in the following order: air (100%), N2 (100%), 20/80 and 40/60 CO2/O2. In accordance with the results, it can be concluded that, by as much to 1 as to 7ºC, the use of the modified atmospheres slowed the growth of the spoilage bacteria of pork meat, favoring the extension of the useful life, mainly in the MAP enriched with CO2.
modified atmospheres; pork meat; shelf life
