Enhancing eco-friendly coatings: Aqueous olive leaves extract fortifies macroalgae-based packaging materials

This study incorporated bioactive compounds extracted from olive leaves (Olea europaea L.) into biodegradable films designed for preserving perishable food items like fruits and vegetables. Olive leaves, sourced from Lesvos island in Greece, yielded three aqueous extracts - OL1, OL2, and OL3 - representing different cultivated species. The antioxidant potential and phenolic compound profile of these extracts were analyzed. Subsequently, these extracts were integrated into 2% sodium alginate solutions, and the resulting mixtures were cast into 90 mm Petri dishes to form solid biofilms. Our findings reveal that the olive leaf extracts offer protection against UV-VIS radiation. Particularly, OL1 showcased the highest antioxidant capacity among the extracts examined. For the solid biofilms, various physical characteristics such as weight, diameter, density, and thickness were measured, alongside evaluating humidity, solubility in water, and water vapor permeability. The rheological properties of these solutions, influenced by temperature and extract addition, affect the viscosity, flow behavior, and gelation capacity, crucial for coating applications. Our research not only explores the impact of olive leaf extracts and glycerol as a plasticizer on biofilm solutions but also sheds light on increased opacity, reduced light absorption, and altered rheological properties. This endeavor aligns with the ongoing pursuit of sustainable packaging alternatives, emphasizing the crucial role of bioactive compounds in enhancing the functionality and ecofriendliness of biodegradable films.