Preparation Of Bioactive Peptides From Crayfish And Preliminary Evaluation Of Its Activity

The study mainly includes three parts:(1) enzymatic production of bioactive peptides from Procambarus clarkii; (2) determination of the content of nutrient compositions and mineral elements; (3) determination of biological activity of hydrolysates in vitro. The specific content and results are as follows:Inspired by reducing power, ·OH scavenging and DPPH · scavenging assay, the optimal enzyme of enzymatic hydrolysis of crayfish muscle was alkali protease, the one of crayfish shell was trypsase. Using single-factor and orthogonal array design,we established that the optimal hydrolysis parameters of alkali protease were hydrolysis time 4h,1:8 of solid/liquid ratio, pH 8.5, enzyme dose of 3.5% and 55℃, and the optimal hydrolysis conditions of trypsase were a hydrolysis duration of 3h,1:10 of the solid-liquid ratio, pH 8.0, a total enzyme concentration of 2.0%, and 35℃. Under the parameters, the DPPH·scavenging rate of crayfish muscle protein hydrolysates reached 85.65% at the concentration of 10 mg/mL, and the rate of crayfish shell protein hydrolysates reached 63.28% at the same concentration. At the same conditions, the effects of crayfish protein hydrolysates on O2-· and ACE inhibition were more and more superior with the increasing concentration of protein.Crayfish was high in protein. The protein content of crayfish muscle was 80.98%(dry weight),the content of shell was 41.66% (dry weight) and the content of hepatopancreas was 48.90%(dry weight). The muscle of Crayfish contained fat 1.32%(natural weight), so it was low in fat.Crayfish muscle, shell and hepatopancreas were detected by atomic absorption spectrometer and atomic fluorescence spectrophotometer. The result showed that Crayfish was rich in mineral elements, especially Ca. The Ca content in crayfish shell was as high as 20164.01mg/kg. The content of Mg, Ca, Fe had the highest proportion in the measured content of mineral elements. Hg and Cd were detected in crayfish muscle, shell and hepatopancreas. It was obviously that Crayfish hepatopancreas had the highest content of heavy metals in three parts, and the Cd content of Crayfish hepatopancreas was above the national standard of Cadmium content.