Proteomics-based Analysis Of Pork Quality Changes At Different Storage Temperatures

The research on preservation and extension of pork shelf life is an important subject in the field of Meat Science in China.In this study,Tibetan pork and Ningxiang black pigs were selected as the research objects.The changes of pork quality and protein were studied at different temperatures(-2? and 4?),which provided a theoretical basis for cold storage and cold chain transportation of fresh pork.In this paper,the freezing point temperature of Tibetan pork and Ningxiang black pork was determined,then stored the pig thigh meat under refrigeration and ice temperature conditions.The shelf life,meat quality and protein changes were determined during storage,and the correlation between the differential protein and quality was analyzed,then comprehensively studyed the mechanism of corruption deterioration of different varieties pork stored at different temperatures.The specific results are as follows:The temperature of Tibetan pork and Ningxiang black pork was monitored during the freezing process.The results show that the freezing point of Tibetan pork was-2.4?,the Ningxiang black pig was-2.3?.The analysis of sensory quality and color of Tibetan Xiang pork and Ningxiang black pig during storage showed that ice temperature storage could effectively delay the generation of bad smell and maintain the stability of pork color.Under the same storage time,the pH,peroxide value and TVB-N value of pork under ice temperature were significantly lower than those under cold storage(P<0.05);the water content of pork under different storage conditions showed an overall downward trend,and the water molecular state was mainly composed of bound water and semi-bound water.With the prolongation of storage time,the secondary structure of pork protein also changed.After storage at-2? the structure of beta folding decreased significantly(P<0.05),the content of beta corner increased significantly(P<0.05),and the structure of irregular curl and alpha-helix did not change significantly(P>0.05).Comprehensive judgment,The acceptable shelf life of Tibetan pork is 18days at-2? and 13 days at 4?.The acceptable shelf life of Ningxiang Black Pork stored at-2? is 16 days,and stored at 4? is 12 days,prolonging by 4-5 days.The effects of different temperature on pork protein were studied comparatively.The GO functions of proteins involved were analyzed.The results show that after 16 days there were 143 differential abundance proteins,of which 85 were up and 58 were down of Tibetan pork stored at-2?;97 differential abundance proteins at 4?,57 were up and 40 were down.After 16 days of storage at-2?,there were 41 differential abundance proteins in Ningxiang black pigs,up to 24 and down 17.there were 51 differential abundance proteins in Ningxiang black pigs at 4?,up to 27 and down 24.GO function analysis was carried out on the proteome of cold-stored pork at different storage temperatures.The main biological processes,molecular functions and cell components were selected.The results showed that the main proteins of pork stored at different storage temperatures were cytoplasm,cytoskeleton,protein-containing complex with ion binding function,cytoskeleton protein binding function and molecular structure activity function.Changes have taken place in the exercise of major functions such as anatomical structure development and biosynthesis.Ningxiang black pork at different storage temperatures is mainly composed of cytoplasm,protein-containing complexes with ionic binding function,proteins involved in cytoskeleton protein binding function and molecular structure activity function,which perform the main functions of cytoskeleton tissue,cell differentiation and anatomical structure development.The differentially expressed proteins of pork stored at different storage temperatures were compared to screen the differentially expressed proteins.The correlation between the differentially expressed proteins and pork quality indexes was analyzed.The effects of different storage temperatures on the differentially expressed proteins were analyzed,and finally affect the meat quality.The results flows that:The results of correlation analysis showed that myosin binding protein C were negatively correlated with pH,TVB-N value and a*value(P<0.01),positively correlated with L*value(P<0.05),and myosin-4 was positively correlated with pH,TVB-N,a*value and b*value(P<0.05),negatively correlated with L*value(P<0.05).Tropomyosin Alpha-3 chain and Tropomyosin Alpha-3 chain were negatively correlated with pH,TVB-N,a*and b*(P<0.05),and positively correlated with L*value(P<0.05);troponin T,troponin I,Troponin I and Troponin C were negatively correlated with pH,TVB-N,a*value and b*value.There were 19 differentially expressed proteins in Ningxiang Black Pork under different storage conditions.Myosin-2 and myoblast binding protein C were positively correlated with TVB-N(P<0.05),phosphorylase B kinase regulatory subunit(Phosphorylase B kinase regulatory subunit)and TVB-N(P<0.05).It and myoglobin were negatively correlated with TVB-N(P<0.05),while Myoglobin was positively correlated with a*and b*values.Structural proteins,cell metabolic enzymes and stress proteins were the main differentially expressed proteins in pork during storage.