Multifunctional performance of gallic acid in biodegradable food packaging films and coatings: Mechanisms, developments, applications, and horizons

There is an increasing interest in the development of degradable and biopolymeric food packaging films (FPFs) based on green ingredients and strategies. To enhance the performance of these films, modifications can be made to the biopolymer molecules, or additives can be incorporated, such as nanomaterials, crosslinkers, bioactive compounds, and other polymers. The use of green compounds is an effective method to improve the performance of degradable FPFs, with gallic acid (GA) being a widely used natural green compound in various biopolymeric films. This review provides an in-depth analysis of GA chemistry and discusses the different types of biopolymeric FPFs crosslinked by GA. Furthermore, it summarizes the recent applications of GA crosslinked biopolymeric FPFs/coatings for food preservation. The comprehensive improvement of biopolymeric films due to GA crosslinking is evident, with the effect on the films’ properties dependent on the concentration of GA and reaction state. The cross-linking of GA with polymer molecules increases the cohesion of the polymer network, with physical and chemical covalent crosslinking being the two main types of cross-linking. Notably, biopolymeric FPFs/coatings crosslinked by GA have demonstrated remarkable effectiveness in preserving fresh foods.