The Preparation and Characterization of an Alginate–Chitosan-Active Bilayer Film Incorporated with Asparagus (Asparagus officinalis L.) Residue Extract

The agricultural production of asparagus generates a significant number of residues rich in bioactive compounds, most of which are wasted. In this study, active edible films with antioxidant and antibacterial properties for food packaging were developed using ethanolic extracts obtained from asparagus residues. These ethanolic extracts of asparagus residue (AspE) were incorporated (1 y 4 wt%) into sodium alginate (SA) solutions for the preparation of alginate–chitosan (SA/CS) bilayer films using the casting method, and they were characterized by optical, structural, mechanical, and thermal properties. In addition, the total phenolic and flavonoid content, antioxidant activity, and antibacterial activity were determined. The results showed that the SA/CS film with 1% AspE had better optical, structural, mechanical, and thermal properties due to its color, flexibility, and homogeneity. Both films incorporated with AspE exhibited antioxidant and antibacterial activity, with higher activity in the film with 4% AspE. However, this film showed shrinkage and surface irregularities that make its application in food packaging difficult, so the formulation with 1% AspE was considered better for this type of application. This study shows that asparagus residues can be a valuable source of bioactive compounds for the food industry, indicating the potential for the valorization of this agri-food waste.