Physicochemical Properties Of Myofibrillar Protein And Myosin In Marine Fish And Freshwater Fish

In this paper,the physicochemical properties of myofibrillar protein and myosin in different fishes(marine fish: golden threadfin bream,turbot,sea bass,mackerel;freshwater fish: largemouth bass)before and after heating were studied.The main research conclusions were as follows:1.There were some differences in the solubility,turbidity,sulfhydryl content and surface hydrophobicity of myofibrillar protein among the five kinds of fishes(golden threadfin bream,turbot,sea bass,mackerel,largemouth bass).After two-stage heating treatment,the turbidity and surface hydrophobicity of myofibrillar protein increased,while the solubility and sulfhydryl content decreased.The surface hydrophobicity of myofibrillar protein of five kinds of fishes(golden threadfin bream,turbot,sea bass,mackerel,largemouth bass)increased by 7.04%,21.97%,59.45%,3.31% and 52.82%,respectively;the turbidity of myofibrillar protein increased by 124.68%,130.29%,149.47%,92.99% and 154.24%,respectively;the solubility of myofibrillar protein decreased by 42.79%,37.81%,28.34%,64.05% and 30.25%,respectively;the content of active sulfhydryl group decreased by 37.12%,47.05%,32.55%,56.06% and57.42%,respectively;the content of total sulfhydryl group decreased by 31.32%,16.82%,23.68%,13.92% and 32.88%,respectively.2.The physicochemical properties,secondary structure and micromorphology of myosin in golden threadfin bream,turbot,sea bass,mackerel and largemouth bass were studied before and after heating.The results showed that the defolding reaction of myosin resulted in increased turbidity,particle size and surface hydrophobicity after heating.After two-stage heating treatment,the turbidity of myosin increased by 234.05%,77.78%,242.17%,25.82% and 59.38%,respectively;the particle size of myosin increased by 25.02%,74.28%,44.27%,123.52% and 78.64%,respectively;the surface hydrophobicity of myosin increased by 63.89%,15.48%,90.53%,21.34% and 75.37%,respectively.3.The changes of myosin tertiary structure of golden threadfin bream,turbot,sea bass,mackerel and largemouth bass before and after heating were studied.After heating treatment,myosin molecules unfold and the internal structure was exposed,which led to the increase of ultraviolet absorbance and the decrease of endogenous fluorescence intensity.After low temperature pretreatment,the fluorescence intensity of myosin in sea bass and largemouth bass decreased from6509.67 and 3415.67 to 4736 and 2784.5 in unheated condition.After two-stage heating,the fluorescence absorption peaks of myosin in golden threadfin bream,turbot,sea bass,mackerel and largemouth bass decreased by 57.05%,52.89%,49.91%,41.00% and 41.91%,respectively.