Influence of high oxygen modified atmosphere packaging on different breeds of chilled pork meat quality and water holding capacity during storage

Abstract: Pork is one of the most commonly consumed meat worldwide, and its quality has received great attention. Pork quality is evaluated by edible quality, nutritional quality, health and safety quality and technical quality, and consumers often rate meat by their nutritional quality and edible quality, which are mainly determined by protein content, meat tenderness and water retention. Meat tenderness has a good linear correlation with cooking loss. Since the chilled meat is susceptible to contamination during the process of storage and circulation, ensuring the quality of chilled meat and meanwhile extending the storage period have great significance for the development of chilled meat. High oxygen modified atmosphere is a new packaging technique, which usually contains 70%-80% oxygen and 20%-30% carbon dioxide and can effectively extend the shelf life of meat. Oxygen can ensure the stabilization of meats' red color and carbon dioxide will prolong the shelf life of meats by inhibiting the microorganism growth. Meat in the high oxygen modified atmosphere packaging will produce a series of complex physical and chemical and biochemical changes, and these changes have important influence on the quality. The investigate the protein oxidation effect on pork quality and water holding capacity when the different varieties chilled pork were stored in high oxygen modified atmosphere packaging. Crossbred pigs (Duroc × Landrace × Yorkshire) (with halothane genotype NN) and Sanmenxia black pigs (without halothane NN gene) were used in this experiment. The changes of CIE* color (L*, a*, b*), protein oxidation, water distribution, water holding capacity and muscle microstructure during the storage at 4℃ in high oxygen modified atmosphere packaging (80% O2 + 20% CO2) were determined. The results showed that with the extension of storage time (0-10 day), carbonyl content increased significantly (P<0.05) and sulfhydryl content declined significantly (P<0.05). The results also showed that myofibril protein oxidation from the 2 types of pigs became more severe with the extension of storage time, which induced the breakdown of the structure of myofibrils. The microstructure of the myofibrils was altered obviously, which was indicated by perimysium rupture, increasing of space between fibers, and loose structure. It was observed that immobilized water converted to free water and thus water holding capacity decreased. Immobilized water of both the crossbred pigs and the black pigs declined significantly (P<0.05) at the 3rd day compared with the control. Compared with that of the control (at the initial state), free water in the meat of the crossbred pigs and the black pigs on the 3rd day decreased, while it increased significantly (P<0.05) on the 5th day for the crossbred pigs and on the 10th day for the black pigs, respectively. Cooking losses of the meat from 2 breeds of pigs increased significantly compared with that of control (P<0.05) when the storage time was longer than 5 d. Meanwhile, CIE* colors of the 2 breeds of pigs were increased at first and then decreased. The L* values of meat from the 2 breeds of pigs reached the maximum on the 7th day. The a* values reached the maximum on the 3rd day. The b* values of meat from the crossbred pigs and black pigs reached the maximum value on the 5th and 7th day, respectively. Results show that high oxygen modified atmosphere packaging has the similar effects on CIE* color, protein oxidation, water state change, water holding capacity and microstructure of meat from the 2 breeds of pigs, which indicates that the effects of high oxygen modified atmosphere packaging on pork meat quality and water holding capacity are universal. The results provide the basis for control pork quality and cooking loss during cooling meat storaged in high oxygen modified atmosphere packaging.