Effect Of Variable Temperature Treatment On Pork Quality And Its Mechanism After Slaughter

Cooled meat means that the pig carcass or the cut meat that has passed the inspection and quarantine is rapidly reduced to 0-4?within 24 h.And in the follow-up links,the meat that has always maintained this temperature has become the mainstream of pork consumption in China.The color,tenderness and water holding capacity of the cooled meat directly affect the sensory quality of the meat and the desire of consumers to purchase.These qualities are closely related to the economic value of the production company.Refrigeration temperature and time are the most important factors affecting pork quality,which directly affects the storage period of chilled meat.Good control of the chilled time and temperature of the chilled meat can ensure the quality of the meat and the shelf life,and reduce the transportation energy consumption of the enterprise,and the cost of cooling meat,and bring more economic benefits.Therefore,this paper takes the longissimus dorsi muscle as the research object,systematically studies the effect of temperature change treatment on fresh pork and its gel properties,and through proteomics technology to study the nature of its changes at the molecular level,revealing the mechanism by which temperature-changing treatment can improve pork quality.This provides theoretical basis and practical guidance for accelerating pork ripening.1.Effect of variable temperature treatment on pork longissimus dorsi muscles quality after slaughterPost-mortem variable temperature treatment t affects the quality of pig longissimus dorsi.In this paper,the longissimus dorsi muscles were used as raw materials,The samples were divided into two treatment groups:one group was as a variable temperature treatment group that was put into 0-4?for 4h,then the samples were transferred 12?for 4 h,Finally,the samples were transferred to 0-4?storage until to 72 h;the other group as a control group,was put into 0-4?until to 72 h.After variable temperature treatment and control treatment,the pH,cooking loss,color,shear force,texture of the post-mortem pork were determined at different times.The results showed that the change of pH during temperature change treatment was faster than that of control treatment.The shearing force and cooking loss were all lower than those of control treatment,and the water retention and tenderness were improved.The L~*,a~*,and b~*values at variable temperature were all generally smaller than control treatments;the hardness and chewiness of the two treatment groups reached the maximum value at 24 h,and the temperature-change treatment group was higher than the control treatment.The elasticity-decline rate of the temperature-change treatment group was slower than that of the control treatment group within 48 h.In terms of cohesion,the difference between the two treatment groups was not significant difference(p>0.05).In summary,variable temperature treatment can improve pork quality more than control treatment.2.Effects of variable temperature treatment after Slaughter on Gel characteristics of Pork meat batters after slaughterIn this paper,the effects of variable temperature treatment on the color,cooking loss,texture,rheological properties and water distribution of pork batters were studied.The results showed that the cooking loss and a~*in the treatment group and the control group reached the optimal value at24 h and 48 h respectively,and the treatment group advanced the cooking loss and a~*optimal time,and the water retention and a~*increased.The treatment group and the control group L*reached the optimal value at 48 h and 72 h,respectively,and the treatment group L~*was higher than the control group,and the b~*change trend was not obvious.The hardness,springness,cohesiveness and chewiness of the treatment group and the control group reached the optimal value at 24h respectively,and the treatment group was better than the control group.but the hardness is not significantly different at 24 h(p>0.05),texture other indicators were significantly different at 24h(p<0.05).The rheological results showed that at 80?,the treatment group G'reached the maximum at 48h,the control group reached the maximum at 72 h,and the treatment group G'maximum was higher than the control group G'.Overall,variable temperature treatment can improve the quality of pork products.3.Proteomics analysis of iTRAQ during variable temperature treatment after SlaughterIn this study,the relative and absolute quantitative isobaric labeling(iTRAQ)method was used to study the changes of protein abundance related to tenderness,water retention and color during temperature change.The activity of the proteome was determined and iTRAQ proteomics analysis was performed.The results showed that based on iTRAQ proteomic analysis,2416proteins were identified,and 14 proteins were significantly associated with tenderness,water retention and color.Among them,the three proteins of Tropomyosin-4,Myosin-2 and Myosin-1played a key role in the temperature-changing process through the differential protein PPT network map.The data in this study provided insights into the proteomics studies of the effects of variable temperature treatment on pork quality.