Effect of acid treatment on extraction yield and gel strength of gelatin from whiptail stingray () skin.

Chemical properties of fish gelatins differ from those of conventional mammalian sources, representing an attractive technological alternative for the food industry. Ray filleting generates a considerable amount of skin waste that can be used as a collagen source for gelatin extraction. Thus, this research evaluated the HCl and CHCOOH effect, at 0.01, 0.025, 0.05, 0.075, 0.1, 0.15, and 0.2 M, on extraction yield, molecular weight distribution, and gel strength (GS) of whiptail stingray () skin gelatins. Results showed differences ( < 0.05) between acid type and concentration used. CHCOOH (0.15 M) gave the highest extraction yield (7.0% . 5.5% at 0.15 M HCl) and GS (653 ± 71 g . 619.5 ± 82 g at 0.2 M HCl). Gelatin electrophoretic profile from CHCOOH revealed α-/β-components and high molecular weight (> 200 kDa) polymers. Ray gelatin GS was higher than commercial bovine gelatin, suggesting its possible use for technological food applications.