Structural characteristics and physicochemical properties of fresh-water fish gelatins with different molecular weights and their potential application to food capsule film fabrication

This work is aimed to investigate the effects of molecular weights on physicochemical properties of fish gelatins and their potential application to food capsule film fabrication. Firstly, high/medium/low component fish gelatins (HCG/MCG/LCG) were obtained by ultrafiltration. Physicochemical property assay results showed that high molecular weight content of gelatin contributed to the increase in gelling strength, viscosity, melting point, and denaturation temperature due to extensive inter-intra molecular interactions. Meanwhile, parameters (temperature, weight ratio, and drying time) had been comprehensively investigated to determine the effects of three molecular weights of gelatins on capsule film manufacture. MCG-derived capsule film was found to achieve good balance among tensile strength, elongation at break, and dissolution rate constant. Furthermore, 90-day acceleration storage stability experiment suggested that MCG showed an appropriate E-amino acid residue content and crosslink density. This work provides a comprehensive insight into the effect of molecular weights on physicochemical properties of fish gelatins and their application in food capsule film manufacture.