Gelatin-based functional films integrated with grapefruit seed extract and TiO2 for active food packaging applications

Gelatin-based functional films were prepared by the addition of grapefruit seed extract (GSE, 5 wt% based on gelatin) and various amounts of TiO2 (0.5, 1.0, 3.0, and 5.0 wt% based on gelatin). TiO2 was evenly dispersed in the gelatin film, but the film surface roughness was increased as the concentration of TiO2 increased. The mechanical strength and water contact angle (WCA) of the composite film were the highest, while the water vapor permeability (WVP) was the lowest when 0.5 wt% TiO2 was used. The addition of GSE slightly reduced the UV light transmittance, but the addition of TiO2 almost completely prevented the UV light transmission. The addition of GSE and TiO2 did not significantly influence the thermal stability of gelatin film. The Gel/GSE/TiO2 composite film showed some antioxidant activity and strong antibacterial activity against E. coli and L. monocytogenes, mainly due to the GSE. The gelatin/GSE/TiO2 composite films with high UV-barrier and antimicrobial functions with some antioxidant activity are likely to be used for active food packaging applications.