Hybrid Biocomposites Based on Chitosan/Gelatin with Coffee Silverskin Extracts as Promising Biomaterials for Advanced Applications.

Biopolymers such as chitosan and gelatin are emerging as leading alternatives to traditional plastic packaging due to their enhanced capabilities and biodegradability. Blends of chitosan and gelatin combine chitosan's antimicrobial and film-forming properties with gelatin's biocompatibility and flexibility. These biomaterials possess tunable mechanical, biological, and physicochemical properties, making them suitable for biomedical, pharmaceutical, food packaging, environmental, and agricultural applications. This study investigates the preparation and characterization of composite biopolymer films based on chitosan and gelatin, incorporating coffee silverskin extract (SSE) as a natural bioactive additive. Coffee silverskin, a by-product of coffee roasting, is rich in phenolic compounds and demonstrates notable antioxidant potential. The objective of this work was to enhance the antioxidant, mechanical, and physicochemical properties of chitosan-gelatin films through the integration of SSE. The biocomposite materials were prepared using solvent casting, followed by extensive characterization techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and UV-Vis spectroscopy. Additionally, color measurements, mechanical properties, and physicochemical properties were assessed. The transmission rates of oxygen and water vapor were also examined, along with the antioxidant activity of the films. The inclusion of coffee silverskin extract facilitated intermolecular interactions between the polymer chains, resulting in improved structural integrity. Furthermore, films containing CSE exhibited enhanced antioxidant activity (up to 28.43% DPPH radical scavenging activity), as well as improved water vapor barrier properties and mechanical strength compared to the pure chitosan-gelatin. The films showed a yellowish appearance. There was a noticeable reduction in the rate of oxygen transmission through the films as well. These results highlight the potential of coffee silverskin as a sustainable source of functional compounds for the development of bioactive materials suited for biodegradable packaging and biomedical applications.