Loach protein was hydrolyzed by Alcalase 2.4 L,Protamex,Papain,PTN 6.0 S and Flavorzyme 500 MG to study the characteristics of different enzymes, as well as the nutritional compositions and scavenging activity on DPPH· of different protein hydrolysates. Results revealed that the protein utilization, the extraction rate of peptides, and the degree of hydrolysis of PTN 6.0 S and Papain hydrolysates were higher than those of others. All of the hydrolysates were rich in glutamic acid，tryptophan and aspartate. The amino acid compositions of hydrolysates were closer to the reference pattern of amino acids. The fractions with molecular weight more than 3000 Da could be hydrolyzed by all of the enzymes. The fractions with molecular weight less than 500 Da were in the main components. The hydrolysate using Alcalase 2.4 L had the strongest scavenging activity on DPPH·. Inferior to it were the hydrolysates of PTN 6.0 S and Protamex. The hydrolysate using Flavorzyme500 MG had the weakest scavenging activity on DPPH·.
