Overheating induced structural changes of type I collagen and impaired the protein digestibility.

Collagen, especially type I collagen, a major component for connective tissue in meat, determines the background tenderness and affects digestibility of meat. Heating may induce great changes in protein structure and its pepsin-treated digestion. The objective of this study was to investigate how heating affected type I collagen structure and in vitro pepsin-treated digestion. Type I collagen was heated at 60 °C, 70 °C, 80 °C for 0.5 to 2.5 h, and the spectrometric measurements and in vitro pepsin digestion were performed. Increased heating temperature caused the exposure of aromatic residues and an elevation of intensity of synchronous fluorescence spectra, but a reduction in the conformational stability of type I collagen (P < 0.05). Under the in vitro pepsin digestion, the Km value of enzymatic reaction increased as heating temperature rose, but overheating attenuated the affinity of type I collagen to pepsin. Heating at 70 °C for 0.5 h is good for type I collagen to get higher digestion.