Abstract:Proteins recovered from surimi rinsing wastewater were used as raw materials to prepare protein hydrolysates with antioxidant and hypoglycemic activities. Single-factor experiments and orthogonal optimization analysis were conducted with five factors, namely substrate mass fraction, pH, enzymatic hydrolysis time, temperature, and enzyme dosage, to determine the optimal process conditions for the preparation of peptides recovered from surimi rinsing wastewater by hydrolysis with a compound protease. The amino acid composition and molecular weight distribution of the peptides were also analyzed. Results indicated that at a substrate mass fraction of 3%, the optimal enzymatic hydrolysis conditions were as follows: temperature: 45 ℃, pH: 8.0, time: 4 h, enzyme dosage: 4 000 U/g prot. Under these conditions, the degree of hydrolysis and peptide content of the obtained enzymatic hydrolysis product were 23.62% and 23.21 mg/mL, respectively. The prepared peptides had a total amino acid content of 58.40 g/100 g and a high hydrophobic amino acid content (22.84 g/100 g) that accounted for 39.11% of the total amino acid content. Molecular weights were mainly concentrated in the <1 kDa range (88.02% of all molecules). Results of in vitro antioxidant and hypoglycemic activity testing revealed that the peptides exerted good scavenging effects on OH• and DPPH• with semi-inhibitory concentrations (IC50) of 8.28 mg/mL and 2.54 mg/mL, respectively. The IC50 values for α-glucosidase and α-amylase were 22.82 mg/mL and 26.31 mg/mL, respectively. In conclusion, peptides prepared by enzymatic hydrolysis of proteins recovered from surimi rinsing wastewater demonstrated good in vitro antioxidant and hypoglycemic effects. The results of this study can potentially provide a novel approach to the high-value utilization of recovered proteins.
