Characterization of chitosan-hydroxypropyl methylcellulose blend films enriched with nettle or sage leaf extract for active food packaging applications

The incorporation of plant leaf extracts into biodegradable food packaging materials is a promising green approach to develop active films with antioxidant and antimicrobial activities. In this context, this study aimed to develop active films based on chitosan/hydroxypropyl methylcellulose blend (CS/HPMC) enriched with sage (SLE) and nettle (NLE) leaf extracts (7.5–15% w/w of biopolymer) to characterize their surface and cross-section morphology, optical, mechanical, water barrier, and antioxidant properties for food packaging applications. Scanning electron microscopy confirmed microstructural integrity and compatibility between CS and HPMC and incorporated leaf extracts. The successful incorporation of plant extracts was confirmed by Fourier transform infrared spectroscopy. Active films showed improvement in UV–Vis light barrier properties (p < 0.05) with opacity value lower than five. Addition of leaf extracts induced a slightly darker color by inducing a green and yellow shade. Addition of NLE increased the water solubility and water vapor permeability compared to the control film (p < 0.05). Total phenolic content and antioxidant activity were increased upon addition of leaf extracts. Overall, CS/HPMC films incorporated with SLE and NLE could be employed as a green alternative for partial substitution of synthetic plastics with antioxidant activity and to prolong the shelf-life of food products.