Extraction and characterization of collagen hydrolysates from the skin of Rana chensinensis.

The production of Hasma generates plentiful non-edible by-products in China and Central Asia. As one of main by-products, the skin of Rana chensinensis is discarded as waste without utilization. In this work, R. chensinensis skin collagen (RCSC) hydrolysates were extracted using pepsin under acidic conditions. The yield of RCSC is 15.1% (w/w). Amino acid analysis revealed that RCSC contained glycine (204.5/1000 residues) and imino acids (182/1000 residues). RCSC exhibited high solubility in acidic pH (1-4) and low NaCl concentrations (< 2%, w/v). Differential scanning calorimetry indicated that the denaturation temperature of RCSC was 33.5 °C. Scanning electron microscopy analysis confirmed their well-defined fibril morphologies. The results indicated that the skin of R. chensinensis is an alternative source of collagen hydrolysates, and RCSC can serve as a potential source applying in foodstuff and medical industry.