Biopolymeric Films and Coatings Based on Purple Corn Flour and Propolis: Physicochemical Properties and Application in the Preservation of Fuerte Avocado

Natural preservation technologies have emerged as sustainable alternatives for maintaining the postharvest quality of fresh products. This study developed and characterized edible films and coatings produced from purple corn flour (MMH) and ethanolic propolis extract (EEP), and evaluated their effectiveness in extending the shelf life of Fuerte avocado. Film-forming solutions were prepared using three MMH/EEP formulations (100/0, 90/10, and 80/20), and their apparent viscosity was determined. Films obtained by drying at 45 °C for 12 h were analyzed for pH, thickness, tensile strength, solubility, water vapor permeability, and microstructure by SEM. The MMH 80/20 EEP formulation showed the best overall performance and was selected as a coating for avocados stored under ambient and refrigerated conditions. Shelf life was defined based on quantitative criteria, including acceptable limits of weight loss and sensory acceptability. Under these criteria, coated avocados reached a shelf life of 30 days at ambient temperature, compared to 15 days for uncoated fruit, and 72 days under refrigerated storage, compared to 50 days for the control. Additionally, the coating reduced weight loss, preserved moisture, and improved sensory acceptance. Overall, MMH/EEP systems represent a promising natural alternative for the postharvest preservation of avocado.