Effect of Heat Treatment on Gelatin Properties of Pepsin-Soluble Collagen from Chicken Bones

The aim of this study was to evaluate the physicochemical composition and gelatin properties of collagen hydrolysates obtained from chicken bones under different heat treatment temperatures (50, 70 and 90°C) and times (30, 60 and 90 min). Results showed that heat temperature can significantly improve the solubility of protein (from 37.8 to 72.1%). Degree of hydrolysis and SDS-PAGE analysis showed that the mean molecular weight of collagen hydrolysates at 50 and 70°C were higher than that of hydrolysates at 90°C, which indicating that the triple-helix structure of protein transmitted to chains and subsequently form protein-protein linkages during heating. FTIR analysis demonstrated that the relative content of β-sheet decreased and random coil increased significantly (P < 0.05), whereas α-helix and β-turn had no significant changes during heating treatment (P > 0.05). Collagen hydrolysates obtained at 90°C for 30 min indicated better gelatin properties (melting temperature, texture profile analysis and microstructure) when compared with that of hydrolysates obtained at 50 and 70°C. Therefore, heat treatment with a relatively higher temperature (90°C) and shorter time (30 min) is necessary to obtain hydrolyzed chicken bones collagen with good gelatin properties.