Antioxidant property and functionality of protein hydrolysate from Chinese softshell turtle (Pelodiscus sinensis)
Jiandong Shen, Bijiang Zhong, Lijun Fu, Bingyan Liu, Wenshui Xia, Qixing Jiang
Abstract
Aquatic animals are vital source for peptides, while information on antioxidant peptides of Chinese softshell turtle is scarce. The objective of this study was to optimize the production of turtle protein hydrolysate (PTH) by proteinase hydrolysis and evaluate its functional property and antioxidant activity. Results revealed that TPH from turtle protein was hydrolysed using protamex. Under the optimum condition (enzyme-substrate ratio of 3500 U/g, pH 7.0, temperature of 50 °C, and 4 h), TPH had the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, with the degree of hydrolysis (DH) of 21.27 ± 1.32%. Obtained TPH contained a high percentage of essential amino acids and its molecular weight of<3000 Da accounted for 99.61%. The solubility of TPH was more than 80% when pH was below 4.0 or above 5.0, and there was no significant difference in its solubility when temperature was 40–100 °C. Meanwhile, TPH exhibited higher emulsifying activity index and the emulsion stability index at pH 7.0 and 10.0. Antioxidant activity studies showed that DPPH scavenging activity, reducing power and ferrous chelating activity of TPH were attained depending on the concentration of hydrolysate. All results indicated that the functional and antioxidant properties of TPH could be beneficial for its application in functional food. • Antioxidant activity of hydeolysate was related with degree of hydrolysis (DH). • Low molecular mass of turtle protein hydrolysate (TPH) had high antioxidant activity. • TPH had good solubility characteristic. • Antioxidant activity of TPH depended on its concentration. • TPH can be used as antioxidant food ingredients.