Abstract: ObjectiveThe present study optimized ultrasonic-assisted enzymolysis conditions for Pinctada fuctada martensii muscle,and analyzed free radical scavenging activity of enzymatic hydrolysate,in order to provide reference for value-added utilization of P.fuctada martensii muscle.Method P.fuctada martensii muscle was taken as the material,single factor and response surface methodology were applied to analyze effects of enzymolysis temperature,protease dosage,ultrasonic power and enzymolysis time on degree of hydrolysis(DH) of protein in P.fuctada martensii muscle,and determine the optimum process parameters,and measure scavenging activity of enzymatic hydrolysate on hydroxyl radical (· OH),superoxide radical(O2) and DPPH free radical(DPPH·).ResultThe factors influencing enzymolysis of P.fuctada martensii muscle in order of their effects were as follows:ultrasonic power>protease dosage>enzymolysis temperature>enzymolysis time.Enzymolysis temperature,protease dosage and ultrasonic power had extremely significant difference on enzymolysis(P<0.01),and interaction between ultrasonic power and enzymolysis time had significant difference (P<0.05).The optimal enzymolysis condition was as follows:enzymolysis temperature was 48 ℃,protease dosage 2200 U/g,ultrasonic power 13% (total output power was 900 W),enzymolysis time 12 min.Under such condition,DH of protein was 21.937%,the relative error to expected value(22.140%) was 0.92%.The scavenging activity of enzymatic hydrolysate on · OH,O~ and DPPH· enhanced as mass concentration of enzymatic hydrolysate increased.When the mass concentration of enzymatic hydrolysate reached 2.0 mg/mL,the scavenging rate for ·OH was 68.85%,scavenging rate for O2-83.62% and scavenging rate for DPPH· 82.36%.ConclusionThe optimized process parameters of ultrasound-assisted enzymolysis are accurate and reliable.Enzymolysis time is shortened and free radical scavenging activity of enzymatic hydrolysate is obvious.Therefore,the enzymatic hydrolysate can be utilized as raw materials of health care food,health care drinks with antioxidation.