Chemical modification of gelatin by a natural phenolic cross-linker, tannic acid

Abstract

Chemical modification of gelatin by a natural phenolic compound tannic acid (TA) at pH 8 was studied, and the properties of the modified gelatin materials were examined. The cross-linking effect was predominant when the TA content was lower, resulting in the formation of a partially insoluble cross-link network. The cross-linking structure was stable even under boiling, and the protein matrix became rigid, whereas the mechanical properties were enhanced. An effective cross-linking effect on gelatin matrix was achieved when the amount of TA was around 3 wt %. Further increase in the TA content enhanced the grafting and branching reactions between gelatin and TA in conjunction with the hydroge..