Influence of Oxygen and Carbon Dioxide Content in Modified Atmosphere Packaging on the Colour and Water-Holding Capacity of Pork Loin

During storage, raw meat is exposed to many external factors, which cause visible changes on the surface of the meat and which affect its water-holding capacity. This study aimed to determine the effect of oxygen content in modified atmosphere packaging (MAP) used for storing fresh pork on the colour, pH, value and water-holding capacity during refrigerated storage. The study also analysed the dynamics of changes in colour using the colour difference (ΔE) coefficient and sensory quality. In the study, slices of pork loin were packed in MAP using the following gas compositions: 55% O2/40% CO2/5% N2 and 75% O2/20%, CO2/5% N2; they were then stored for 15 days at a temperature of 4 °C. The colour of pork stored in MAP was significantly affected by time, but not by the proportion of oxygen. During storage, the meat’s lightness (L*), yellowness (b*), chroma, and hue angle increased, whereas its redness index (a*/b*) decreased. Significant differences in colour between freshly packed and stored samples were noted after days 7 and 9 in MAP containing 55% and 75% oxygen, respectively. The values of pH, free water, and purge and cooking loss were not affected by gas concentration but changed over time. Lowering the oxygen content from 75% to 55% in MAP opens the possibility of reducing the oxygen demand from the meat industry without compromising the quality of the meat.