Enhancing the properties of fish gelatin edible film by proanthocyanidin-titanium coordination crosslinking effect

Poor mechanical of the fish gelatin film has severely limited its application in food industry. To solve this problem, the titanium (Ti4+) was incorporated with proanthocyanidin (PA) polymer, dimer and monomer respectively, then applied as crosslinkers to improve the quality of the gelatin film. Results showed that, film crosslinked by PA incorporated with Ti4+ showed significantly better mechanical properties than crosslinked by PA or Ti4+ along, which indicated coordination effects during crosslinking. Furthermore, polymerization degree (PD) of the PA were shown to have positive impact on the crosslinking reactions, the higher the PD of the PA, the better the properties were shown by films. To explain these observed coordination effects, ATR-FTIR, X-ray diffraction spectrum and fluorescence spectrometry were used to investigate the crosslinking reaction, and PA-Ti4+ chelating reaction were found to responsible for the coordination. Results from high-performance size exclusion chromatography- evaporative light scattering detector (HPSEC-ELSD) and zeta sizer analysis indicated the coordination crosslinking effects were positively related with the PD of the PA. The antioxidant ability, hydrophobicity and morphrology were also improved by the PA-Ti4+ coordination effect. The results will provide useful information for developing high-quality gelatin edible film.