Rheological Properties and Antioxidant Activity of Gelatin-Based Edible Coating Incorporating Tomato (Solanum lycopersicum L.) Extract

Gelatin is a promising biopolymer for edible coatings thanks to its low cost and gelling properties. However, its weak mechanical properties limit its use. This study aimed to develop a gelatin coating with tomato extract, analyzing its antioxidant activity and rheological properties for food applications. Gelatin concentrations (2, 5, and 7%) were evaluated, and it was determined that 7% with 7.5% glycerol was the optimal mixture. Three concentrations of tomato extract (0.5, 1, and 1.5%) were added, and antioxidant activity was evaluated using the ABTS technique, as well as the interaction of components through FT-IR and physicochemical analysis. The results showed that there were no significant differences in terms of their physicochemical characterization, maintaining a pH of 5 and a yellowish hue. The FT-IR spectra indicated there were hydrogen bond interactions between gelatin and the extract. The antioxidant capacity was higher with the 1.5% extract, achieving an inhibition of 58.9%. It was found that the combination of the different materials used improved the rheological (specifically the viscosity and stability of the material) and antioxidant properties of the gelatin. These findings suggest that modified gelatin coatings may be effective in extending the shelf life of foods.