Comparative study on characteristics of gelatin from the skins of brownbanded bamboo shark and blacktip shark as affected by extraction conditions

Gelatins from the skins of brownbanded bamboo shark (BBS; Chiloscyllium punctatum) and blacktip shark (BTS; Carcharhinus limbatus) were extracted using the distilled water at different temperatures (45, 60 and 75 °C) and times (6 and 12 h). Yields of gelatin from the skins of BBS and BTS were 19.06–22.81% and 21.17–24.76% (based on wet weight), respectively. Gelatins from both species extracted at 45 °C for 6 h exhibited the highest bloom strength (206–214 g), which was higher than that of commercial bovine bone gelatin (197 g) (p < 0.05). Gelatin gels from BBS skin could set at room temperature (25–26 °C) within 24 min. However, gelatin gels from BTS skin was not able to set within 3 h at the same temperature. Scanning electron microscopic study showed that gelatin gel from BBS skin presented the thicker strand than those from BTS skin and bovine bone. Cross-linked components (β- and γ-chains) and α-chains were more degraded with increasing extraction temperatures, especially at 75 °C. Gelatin from BTS skin was more susceptible to hydrolysis than that from BBS skin. Fourier transform infrared (FTIR) study revealed that the major absorption bands of gelatin from the skins of both sharks shifted to a higher wavenumber, compared with their corresponding acid soluble collagen (ASC). Therefore, gelatins from the skin of BBS has a potential to replace mammalian for gelatin, due to its similarity in bloom strength and setting behavior to the commercial bovine bone gelatin.