Preparation and characterization of gelatin-carboxymethylcellulose active film incorporated with pomegranate (Punica granatum L.) peel extract for the preservation of raspberry fruit

Abstract

Active films composed of gelatin and carboxymethylcellulose incorporated with pomegranate peel extract (PPE) were elaborated and characterized. PPE compound identification studies were carried out, and the physicochemical properties of the films and their ability to preserve raspberries under refrigerated conditions (2 °C) were determined. Among the major phytocomponents analyzed by LC-QTOF MS, α and β-punicalagin were identified along with 15 other components. Significant increases in mechanical properties (3.22–8.96 N) and antioxidant activity (18.19–91.15%) were observed when adding PPE (p < 0.05). Increasing the PPE concentration was also shown to reduce UV-light transmission through the films, and color changes occurred at different pH values due to the polyphenol content. The FTIR spectra indicated the transformation of α-helix to β-sheet structures by adding PPE to the films. SEM analysis indicated significant microstructural changes with the incorporation of PPE. The preservation results showed that extending raspberries' shelf life to 15 days was possible. These results revealed the potential of gelatin-carboxymethylcellulose with PPE in manufacturing films with antioxidant, UV-light barrier, and pH-sensitive properties for preserving raspberries.