Improving the crosslinking of collagen casing and glutaraldehyde by facilitating the formation of conjugate structure via pH

Glutaraldehyde (GTA) crosslinking is commonly used to improve the thermal stability and mechanical strength of collagen casings. The aim of this research was to determine the optimal pH of the crosslinking between GTA and collagen as well as the crosslinking mechanisms. The weakly alkaline environment could facilitate the generation of GTA polymerization through the rapid generation of -C = C-C = O and -N = C-C = C- conjugated structures, and enhance the crosslinking reaction of GTA polymers with collagen amino groups. In the pH range of 8–10, the fibril diameter and d-space value declined significantly in the self-assembled collagen fibril-GTA system. Meanwhile, collagen casing films crosslinked with GTA in weakly alkaline conditions exhibited higher mechanical strength and thermal stability. These results suggest that the crosslinking of collagen casings and GTA can be improved by adjusting the pH. Possible crosslinking mechanisms related to the formation of conjugated long chains have also been proposed. This study could provide guidance on the appropriate use of GTA in the production process of collagen casings.