Accelerated Aging of Starch-Gelatin Films with Enzymatic Treatment

Biodegradable films combining proteins and polysaccharides are considered a sustainable alternative for replacing polymers of fossil origin. Starch and gelatin stand out in this field, since they enhance the stability of the blend, improving physical, thermal and chemical properties of the films. However, there are challenges involved in replacing traditional synthetic polymers with materials from renewable sources, related to structural and functional stability during storage and use. Therefore, it is necessary to study alternatives that may lengthen the useful life of these polymers, making their applicability feasible. In this context, the present study aimed to synthesize and characterize cornstarch and gelatin films treated enzymatically, evaluating the effect of the transglutaminase enzyme (TGase) on the degradation behavior of the film through accelerated aging. The characterization of the films evaluated water solubility, water vapor permeability, mechanical properties, thickness, water activity, thermal properties and functional groups. Subsequently, the films were exposed to three different accelerated aging processes that allowed the simulation of possible applications: thermal oxidation (TO), ultraviolet radiation (UV) and humidity (UR) exposure for 64 h. The results indicated that the TGase contributed to a lower solubility (25% decrease) while starch made the films more soluble. The comparison of films with (ME) and without enzyme (WE) showed that the TGase increased the tensile strength and elongation at break by 20% and 12%, respectively. The enzyme effect could clearly be noted after accelerated aging. A larger impact was observed on tensile strength values, and the enzyme treated film exhibited a higher performance during UR exposure: only 80% mechanical degradation for ME films when compared to 89% on WE films. The results suggest that TGase has a positive effect on the films, which can be applied to products and/or humid environments at mild temperatures. [GRAPHICS] .