Study On Proteolytic Properties,Flavor Characteristics And Antioxidant Activity Of Large Yellow Croaker(Pseudosciaena Crocea)in Vitro And In Vivo

Large yellow croaker（Pseudosciaena Crocea）has high nutritional value,which is rich in protein,vitamin E and other nutrients.The amino acid composition ratio of protein is balanced,and the utilization value space is huge.Large yellow croaker proteolysis can decompose large molecular protein into small molecular weight of short peptide,which is more conducive to human absorption and utilization.Accordingly,based on the large yellow croaker protein as the main research object,uses the proteolytic digestion technology,system large yellow croaker proteolytic digestion process conditions were studied and the enzymolysis liquid of flavor substances,and explores the large yellow croaker liquid protease solution on the antioxidant activity in vivo and in vitro,aims at providing a large yellow croaker protein resources development and utilization to provide theoretical basis and experimental basis.The main research results are as follows:（1）The technology of enzymatic hydrolysis was optimized by single factor and response surface analysis,and the enzymatic hydrolysate was analyzed by SDS-PAGE under different enzymatic hydrolysis time,the antioxidative activity of the hydrolysate of the large yellow croaker was evaluated in vitro at four concentrations at different enzymolysis time.The results showed that the optimum enzymolysis technology was as follows:neutral protease0.4%,substrate concentration 25.0%,enzymolysis temperature 45°C,enzymolysis time 7 h,Ph 7.0,the reducing power of the enzymolysis liquid was 0.951,the DH was 37.51%and the O₂^-·was 82.42%.The results of SDS-PAGE showed that the actin disappeared completely after 7 h of enzymatic liquid,and the molecular weight of myosin light chain was 27kda,15kda and 6KDA.The results of in vitro antioxidant test showed that YCP-Ⅳshowed high antioxidant activity.（2）Electronic nose combined with HS-SPME-GC-MS was used to analyze the flavor characteristics of protease hydrolysate of large yellow croaker.The influence of enzymolysis time on volatile substances in the enzymolysis solution was investigated.According to PCA and LDA,the electronic nose test data showed that there were differences in flavor components of the enzymolysis solution under different enzymolysis time,and the enzymolysis solution at 1 h and 3 h had similar flavor.The electronic nose sensor W1W and W2W have the best ability to distinguish the flavor of enzymatic hydrolysate.By GC-MS,there were 27 volatile flavor compounds,mainly aldehydes and hydrocarbons.Enzyme solution 1 h,3 h,5 h,7 h of enzymatic hydrolysis liquid were detected in 18,19,20,28 kinds of volatile compounds,including 7 h enzymolysis liquid is 1,3,5 h enzymolysis liquid than the generated several unique flavor substances,such as dodecyl aldehyde,3-Octanone,amyl butyrate,ethenylhexanoate,etc.（3）Use of D-galactose mice aging model was constructed to further study on large yellow croaker proteolytic digestion liquid YCP-Ⅳantioxidant effect in the body.Results showed that:compared with model group,YCP-Ⅳmiddle and high dose group in mice liver,spleen and thymus index decreased,in mice liver and serum SOD,CAT and GSH-Px activity increased significantly,the MAD content decreased significantly.In the pathological sections of mice heart and kidney,with the increase of YCP-Ⅳdosage of proteolytic fluid of large yellow croaker,the aging effect of mouse heart and kidney was significantly reduced,the arrangement of cardiac cells was regular,and the structure of glomerulus was intact without obvious atrophy.Research results show that the large yellow croaker YCP-Ⅳproteolytic digestion liquid can improve the oxidative stress mice antioxidant enzyme activity,promote the mice organism ROS removed,thus effectively ease and improve the aging mice.