Effects of CO₂ on the physicochemical, microbial, and sensory properties of pork patties packaged under optimized O₂ levels

The storage quality characteristics of fresh pork patties were investigated under 80% O-2 modified atmosphere packaging (MAP80:20 = 80% O-2/20% CO2) and 40% O-2 MAP with various CO2 levels (MAP40:20 = 40% O-2/20% CO2/40% N-2; MAP40:40 = 40% O-2/40% CO2/20% N-2; MAP40:60 = 40% O-2/60% CO2). Packaged patties were stored for 16 days at 4 degrees C to monitor their physicochemical (pH, instrumental color, oxidative stability, and fatty acid profile), microbial, and sensorial changes. Results suggested that decreasing O-2 levels from 80% to 40% significantly inhibited the lipid oxidation of patties but led to a lower (P < 0.05) color stability. Elevating CO2 levels from 20% to 60% in combination with 40% O-2 significantly suppressed bacterial growth and total volatile basic nitrogen production, and thus rendered patties with a better sensory quality and a similar meat color to 80% O-2. However, increased CO2 levels promoted lipid oxidation through reducing the antioxidant capacity of patties, which was attributed to a CO2-induced reduction in superoxide dismutase and glutathione peroxidase activities during storage rather than a pH reduction or changes in fatty acid composition. Overall, 40% O-2/40% CO2/20% N-2 is a realistic alternative for pork patties to improve meat quality and extend the shelf-life to over 16 days.