Functional properties of sharpnose stingray (Dasyatis zugei) skin collagen by ultrasonication extraction as influenced by organic and inorganic acids

Abstract

The aim of this study was to extract acid-soluble collagen from the skin of the sharpnose stingray using organic (acetic) and inorganic (hydrochloric) acid via an ultrasound-assisted method. The pre-treated stingray skin was extracted by 0.5M acetic acid and hydrochloric acid under ultrasonication treatment for 30 min. The collagen's properties, including viscosity, rheology, water-holding capacity (WHC), emulsifying stability index (ESI) and solubility, were determined. The yield of collagen extracted using acetic acid (11.49 ± 0.03%) was significantly higher than the yield extracted using hydrochloric acid (3.50 ± 0.01%) (p < 0.05). The viscosities of both extracted collagens were thermally stable, with a high thermal denaturation temperature (Td). The viscoelastic properties of collagen extracted using acetic acid were higher than those of collagen extracted using hydrochloric acid. The WHC and ESI for extracted collagen using acetic acid were significantly higher (47.8%, 15.01 min) than those of extracted collagen using hydrochloric acid (20.08%, 12.91 min), respectively. Both extracted collagens had higher solubility in an acidic pH range (pH 1–5) and the lowest solubility at a basic pH range (pH 9–10). Hence, these findings showed that the collagen extracted by ultrasound using acetic acid gave a higher yield and better properties than collagen extracted using hydrochloric acid.