Characteristics and Gel Properties of Gelatin from Skin of Asian Bullfrog (Rana tigerina)

Characteristics and gel properties of gelatin from frog skin as influenced by extraction temperatures (45-75 A degrees C) were investigated. Yield of gelatin increased as the extraction temperature increased (P < 0.05). All gelatins contained alpha- and beta-chains as the predominant components and showed a high imino acid content (215 residues/1000 residues). Fourier transform infrared (FTIR) spectra indicated that all gelatin samples had major peaks in amide regions. Gelatin extracted at 55 A degrees C exhibited the highest gel strength (P < 0.05), which was similar to that of commercial bovine gelatin (P > 0.05). Gelling and melting temperatures of frog skin gelatin were 23.47-24.87 and 33.22-34.66 A degrees C, respectively. Gels became more yellowish with increasing extraction temperatures (P < 0.05). All gelatin gels were sponge or coral-like in structure but varied in patterns as visualized by scanning electron microscopy (SEM). Gelatin from frog skin could be used as a replacement for land animal counterpart.