Efficacy of different storage practices in maintaining the physicochemical and microbiological properties of fresh pork sausage

Fresh pork sausages, overwrapped with oxygen-permeable films or packed under modified atmosphere (MAP; 65% O₂ and 35% CO₂), immediately after production or after 1-day storage at 0C, were stored either at 2C in a domestic refrigerator or at 5C in a refrigerated display cabinet beyond the commercial terms. pH, Aw, lipid oxidation, color and microbial counts were evaluated during storage (3, 6 and 9 days for overwrapped and 6, 12 and 15 days for both MAP practices). pH showed a significant decrease in all packed samples, especially at 5C. Lipid oxidation slightly increased in all sausages and more markedly under high O₂ concentrations of MAP. Discoloration (a*) was noticed in all samples, both in the external and internal surfaces, more clearly under light exposure of the cabinet. Spoilage bacteria increased under both packaging conditions and more markedly at 5C. A shelf-life extension beyond the commercial term of 6 days might be considered only for oxygen-permeable film packaging. On the contrary, it seems difficult to maintain pork sausage quality up to 12 days (commercial term) and beyond under the high O₂ concentrations of MAP. This study deals with the evaluation of two different and commonly employed packaging conditions (oxygen-permeable film and modified atmosphere) on extending shelf-life of fresh pork sausages stored under refrigeration. Changes on selected physico-chemical and microbiological properties were evaluated at different time intervals. These findings can be useful for researchers, manufacturers and traders of pork products to estimate both advantages and disadvantages in the application of different packaging systems by hygienic, qualitative and economic point of views. A simple, rapid and quantitative determination of color indices markedly suitable for pork products that showed a complex and uneven food surface was also presented.