| This study used bovine semitendon muscle as the raw material,and applied scanning electron microscope,texture analyzer,SDS-PAGE and other test indicators to study in depth the quality change law and myoglobin pigment of bovine semitendon muscle during cold storage by water bath heating.Myofibrillar protein degradation,protein oxidation and fat oxidation,protein aggregation,changes in myofibrillar structure and rainbow stains.The test used fresh bovine semitendon muscle as the test material,which was heat-treated in a water bath(97?)so that the center temperature was 70,80,and 90?,respectively,and refrigerated at 4? for 0 to 5 days.index.The research results are as follows:1.Effects of water bath heating on the quality of cold storage and protein degradation of semi-tendonTo study the pH,water retention,myoglobin pigment,myofibrillar protein degradation,to explore the relationship between quality changes,myofibrillar structure and rainbow stains.The results show that with the increase of the heating temperature of the water bath and the extension of the refrigerating time,the intensity of the rainbow stains of the bovine semitendinosus muscles continues to increase;the pH value of the meat samples treated by the 70? water bath is lower than that of the meat samples treated by the water baths of 80 and 90 ?,and There are significant differences(P<0.05).During cold storage,the pH value of the meat samples treated with water bath at 80? and 90 ? showed the trend of decreasing first and then rising;the water retention of meat samples in the water bath treatment group at 70 ? was significantly decreased on the first day of cold storage.The meat-like water retention decreases in the later period of refrigeration;with the increase of temperature and the extension of refrigeration time,muscle pigment myoglobin is continuously oxidized and converted into methemoglobin;with the extension of refrigeration time,the myofibrillar solution becomes small The index is also increasing,and the trend is obvious.SDS-PAGE:the main myosin(245 kDa)and actin(75 kDa)are degraded,and new small molecular weight proteins are generated at 30 kDa,which shows that the water bath heating temperature Refrigerating time promotes the degradation of myofibrillar protein.According to the above research results,with the rise of the water bath temperature and the extension of the refrigerating time,the rainbow stains of the bovine semitendon muscles increase,the quality decreases,the protein degrades,and the tissue structure can better meet the conditions for the rainbow stains,making the rainbow stains with temperature The increase is more significant with the extension of storage time.2.Correlation between changes in rainbow stains of bovine semitendinosus muscle heated in water bath and protein and fatty oxygenTo study the changes of non-heme iron content,protein and lipid oxidation,color and other related indicators,and to explore the relationship between protein fat oxidation and rainbow spots.The results show that with the increase of the heating temperature of the water bath and the extension of the refrigerated time,the intensity of the rainbow spot of the semitendinosus muscles of the cattle increases continuously,in which the brightness value(L*)and yellowness value(b*)increase slightly,while the red The degree value(a*)decreased slightly,and all showed significant differences(P<0.05).During cold storage,the non-heme iron content,thiobarbituric acid reactant value,and carbonyl content of the bovine semitendinosus muscle increased significantly(P<0.05),the content of free sulfhydryl group decreased significantly(P<0.05);the correlation analysis showed that the intensity of rainbow spot of bovine semitendinosus muscle was significantly positively correlated with non-heme iron content,carbonyl content and TBARs value(P<0.05),significantly negative correlation with free thiol content(P<0.05),and extremely significant negative correlation with a*(P<0.01),which may be due to higher non-heme iron content promoting TBARs in refrigerated 0 to 1 At d,it rises rapidly,and at the same time promotes the process of protein oxidation.The process of protein and fat oxidation occurs simultaneously and promotes each other,thereby affecting the formation of rainbow spots.3.The relationship between the changes of rainbow stains and the structure of myofibrillar fibrillation in the cold-water heated bovine semitendinosus muscleTo study the changes of myofibrillar protein solution turbidity,surface hydrophobicity,texture,and myofibrillar structure,and to explore the relationship between myofibrillar structure and rainbow stains.The results showed that the turbidity of the myofibrillar protein solution increased with the increase of the heating temperature of the water bath and the extension of the refrigerating time.On the 5th day of cold storage,the surface hydrophobicity of myofibrillar protein decreased significantly(P<0.05),and the protein gradually became denatured;the texture parameters of meat such as hardness,adhesiveness,and chewability were greatly affected by heating temperature and storage time.The trend of its change with heating temperature and cold storage time is different;the semitendinosus muscle treated at 70 ?,due to the contraction and degeneration of the muscular endometrium and myometrium,the muscle fiber gap narrows;the semi-tendon treated at 80? The muscle fascia in the muscle changes significantly,the diameter of the muscle fiber increases slightly,and the gap between the muscle fibers decreases.In the semi-tendon muscle treated at 90?,the adjacent muscle fibers are arranged tightly and densely.With the extension of the refrigeration time,the overall cut plane becomes more and more smooth,the myofibrils are more and more dispersed,the gap between them is larger and larger,and the arrangement of the cut myofibrils is more and more regular.Therefore,the combined changes of muscle fiber structure and connective tissue membrane at different temperatures form rainbow stains. |
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