Study on Enzymatic Hydrolysis of Tuna Powder and Functional Activity of Enzymatic Hydrolysis Products

In order to develop the deep processing of tuna powder,the enzymatic hydrolysis technology of tuna meal was studied and the efficacy of enzymatic hydrolysate was evaluated. The enzymatic preparation was screened with the degree of hydrolysis as the index,and the technological parameters of enzymatic hydrolysis were optimized by response surface test design. The total reducing power,free radical scavenging rate,tyrosinase inhibitory rate and the antimicrobial activity of the enzymatic hydrolysate were tested. The results showed that the optimum conditions for enzymatic hydrolysis of tuna meal with alkaline protease were as follows:Ratio of feed to liquid 1:5 (g:mL),amount of enzymatic addition 1×10⁴ U·g^-1,temperature 55℃,time 8 h and pH10.5.Under these conditions,the degree of hydrolysis was 29.20%±0.08%,and the content of amino acid nitrogen was 7.57 mg·mL^-1. The hydrolysate had a good scavenging rate for hydroxyl radicals and increased with the increase of ammonia ground nitrogen concentration. The total reducing power of the hydrolysate was close to that of vitamin C of 0.4 mg·mL^-1 when the concentration of amino nitrogen was 7.57 mg·mL^-1.The inhibitory effect of enzymatic hydrolysate on tyrosinase was enhanced with the increase of amino nitrogen concentration and its IC₅₀ was 3.44 mg·mL^-1. The enzymolysis solution also had a certain inhibitory effect on E. coli. The results of this study provide an experimental basis for the high-value development of tuna powder.