The Study On Anti-fatigue Effect And Antioxidant Activity Of Hydrolysates From Auxis Tapeinosom Dark Muscle Protein

Auxis tapeinosoma is a kind of low-value fish species,of which dark muscle are byproducts from the seafood industry and are generally used to produce low-market-value products,such as fishmeal and pet food on account of their dark color,oxidation,off-flavors and poor functional properties.In order to improve its added value and utilization level,dark muscle proteins was extracted by alkali solution acid in this study,the restriction enzymolys was employed to prepare dark muscle protein hydrolysate(DMPH).Its elementary composition,amino acid composition and anti-fatigue effect were investigated and compared with DMH,preliminarily speculated the main anti-fatigue active substance in dark muscle hydrolysate(DMH).The active composition in DMPH was separated by ultrafiltration,and four fractions including DMPH-Ⅰ(> 10 k Da),DMPH-Ⅱ(5-10kDa),DMPH-Ⅲ(3-5kDa)and DMPH-Ⅳ(<3kDa)were obtained.The in vitro antioxidant activities of the four fractions were invest igated,the anti-fatigue effect of the ultrafiltration fractions with strong a ntioxidant activity were evaluated and the relationship between antioxidant activities and anti-fatigue effect were discussed.The main results are as follow: 1.The content of crude protein in DMPH was significantly higher than DMH,its content of ash and crude fat was significantly lower than DMH.DMH and DMPH.The amino acid composition of DMH and DMPH were comprehensive.The amino acid content of DMPH was higher than DMH.The contents of tyrosine,methionine,histidine,lysine and tryptophan in DMPH were higher than DMH.The contents of branched chain amino acid in DMPH were higher than DMH.The contents of glutamic acid and aspartic acid in DMPH were higher than DMH.2.DMH and DMPH could significantly increase swimming time of mice and reduce consumption of liver glycogen,they also helped eliminate the accumulation of metabolites by reducing lactic acid and urea nitrogen levels,both DMH and DMPH had anti-fatigue effects and no significant difference.The contents of crude protein and amino acid in DMPH were higher than DMH.It could be speculated that amino acids and peptide hydrolysed from dark muscle protein maybe the main ant i-fatigue active substances in DMH.3.DMPH ultrafiltration fractions exhibited scavenging activity of 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radicals,hydroxyl radicals and had certain reducing power.DMPH-Ⅱ and DMPH-Ⅲ had stronger DPPH free radical scavenging activity and reducing power.DMPH-Ⅰ and DMPH-Ⅲ had stronger hydroxyl radical scavenging activity.Comprehensively consideration,DMPH-Ⅱand DMPH-Ⅲ were used to further study anti-fatigue effect.4.DMPH-Ⅱ and DMPH-Ⅲ could significantly increase swimming time of mice and reduce consumption of liver glycogen and eliminate the accumulation of metabolites by reducing lactic acid and urea nitrogen levels.It also improved the activity of endogenous cellular antioxidant enzymes in mice.Both DMPH-Ⅱ and DMPH-Ⅲ had anti-fatigue effects and no significant difference.Anti-fatigue effect of DMPH ultrafiltration fractions was correlated with their antioxidant activities.