Study On Meat Quality Changes And Processing Suitability Of Pork In Different Parts After Slaughter

The purpose of this study was to explore the changes in meat quality during the post-slaughter ripening of different parts of Tibetan pork to obtain the appropriate ripening time,and to explore the suitability of processing of different parts of Tibetan pork by using different processing methods.It is expected to provide a theoretical basis for promoting the development of Tibetan pork processing industry and increasing the income of meat production,processing and sales industry.The specific research contents and results are as follows:1.The changes in meat quality of different parts of Tibetan pork during the maturation process after slaughter were studied.The foreleg meat,longissimus dorsi muscle and hindleg meat of Tibetan pigs were selected as the research objects,and the nutritional composition,p H,color,water retention,cooking loss and shear force during the maturation process were measured every 12 h.(1)There was a significant negative correlation between the maturation time of Tibetan front leg meat after slaughter and shear force(P<0.01);There was a significant positive correlation between drip loss and storage loss(P<0.01).There was a significant negative correlation with a* and crude fat(P<0.05).The moisture content at 12 h of ripening was significantly decreased(P<0.05),but had no significant change with the increase of ripening time(P>0.05).There was no significant change in fat content during the whole ripening period(P>0.05).The shear force reaches its maximum value at 24 h and begins to decrease.At 36 h of ripening,p H decreased to the lowest value and cooking loss reached the maximum.At this time,the water retention of muscle was the worst,the color of muscle was better,and the optimum ripening time of foreleg meat was 48 h.(2)The postmortem maturation time of longissimus muscle was positively correlated with storage loss and drip loss(P<0.01).There was a significant negative correlation with moisture and shear force(P<0.01).There was a significant positive correlation between L* and a*(P<0.05).At 24 h,muscle moisture content and p H were significantly decreased(P<0.05).There was no significant change in crude fat content during ripening(P>0.05).At 48 h,the p H reached the lowest value,the cooking loss rate reached the maximum value,and the shear force reached the lowest value and began to decline at 36 h.At this time,the muscle tenderness became smaller,the flesh color was rosy and shiny,and the water retention was the worst.The analysis showed that the optimum maturity time of Longissimus dorsi muscle was 60 h.(3)There was a significant negative correlation between the shear force of hind leg meat at maturity time(P<0.01).There was a significant positive correlation with storage loss and drip loss(P<0.01).At 24 h,moisture content and p H were significantly decreased(P<0.05),ether extract content and shear force reached the maximum values of 3.42% and 58.77 N,respectively.When mature to 36 h,p H reaches the limit p H,muscle water retention is poor.At 48 h,L* and a* of the hind leg meat reached the maximum,which was the best time for the hind leg meat to mature.After comprehensive analysis of each index,it is concluded that 48 h is the mature time of the whole carcass.2.After 48 h of maturity,the three parts of the stored pork were processed by boiling,roasting and roasting methods,and the yield,color difference,texture,shear force,microstructure changes and volatile flavor substances were measured.The processing suitability was explored combined with sensory evaluation.Finally,the following results were obtained: After boiling,the yield and color of foreleg meat were lower than those of the other two methods,but its tenderness was the best and the relative content of flavor substances was the highest.Based on the comprehensive analysis of sensory evaluation scores and various indexes,it was concluded that foreleg meat was the most suitable cooking and processing method.The baking method of longissimus dorsi muscle had the highest yield,the best color difference and tenderness,and the variety and content of flavor substances were relatively more,but the score of sensory evaluation was slightly lower than that of roasting and processing method.Based on the comprehensive analysis of the score of sensory evaluation and each index,it was concluded that roasting and processing method of longissimus dorsi muscle was the most suitable,followed by roasting method.After roasting,the yield and color difference of hind leg meat were better than those of the other two methods.Roasting method had the best tenderness but poor chewability.Roasting method had the highest relative content of volatile substances and the highest comprehensive score of sensory evaluation.3.The moisture migration and microstructure changes of meat samples and fresh meat samples processed by different methods were measured.Finally,it was concluded that the content of free water of Tibetan pig front leg meat after boiling was significantly higher than that after roasting and roasting(P<0.05),and the boiling processing had a great effect on its microstructure,which made the muscle fiber gap larger.The content of free water in longissimus dorsi muscle of Tibetan pigs after roasting was significantly higher than that in roasting and boiling(P<0.05).The microstructure of longissimus dorsi muscle samples after cooking and roasting had significant changes,and the space between muscle tracts was larger than that in roasting and fresh meat samples,indicating that cooking and roasting had a greater effect on the muscle fiber structure.The content of free water in the meat after roasting was significantly higher than that after roasting and boiling(P<0.05).The gaps between muscle tracts of the meat after cooking and roasting were larger,indicating that cooking and roasting had a greater effect on the microstructure of the meat.