Recovery and physicochemical properties of smooth hound (mustelus mustelus) skin gelatin

Gelatin was extracted from the skin of smooth hound after pre-treatment with acetic and citric acids. The addition of smooth hound crud acid protease (SHCAP) at a level of 15 Units/g alkaline treated skin resulted in an increase yields of gelatin. The hydroxyproline yields of gelatins extracted for 24 h with acetic acid and with SHCAP were 17.34% and 56.82%, respectively. While the serine content recorded for the smooth hound skin gelatin (SHSG) extracted with SHCAP was higher than that of halal bovine gelatin (HOG) (36 versus 29 residues per 1000 residues), hydroxyproline and praline (202 residues per 1000 residues) contents were slightly lower (219 residues per 1000 residues). The gel strength of the gelatin gel from SHSG (211 g) was lower than that of HBG (259 g) (p < 0.05). Compared to HBG (p < 0.05), SHSG was noted to exhibit lower emulsifying, foaming, and fat-binding properties but similar emulsifying stability. SDS-PAGE revealed that SHSG showed high band intensity for the major protein components, especially alpha- and beta-components, which was comparable to that of standard calf skin collagen type I. In conclusion gelatin extracted from smooth hound skin has good quality and can be used in the food industries. (C) 2012 Elsevier Ltd. All rights reserved.