Spent malt-derived activated carbon carrier in active films for banana preservation

Biodegradable active packaging is a promising strategy for reducing postharvest losses and delaying fruit ripening. This study developed poly(vinyl alcohol) (PVA) active films containing activated carbon derived from spent brewer's malt (MAC) as a carrier for Clitoria ternatea bioactive compounds and evaluated their effectiveness in preserving ‘Prata’ bananas. MAC was loaded with C. ternatea phenolic compounds and incorporated into PVA films using an emulsion-based system. Bananas were individually packaged with films containing emulsion, MAC, or MAC loaded with bioactive compounds from extracts at 5, 10, and 15 g L⁻¹, with PVA-packaged and unpackaged fruits as controls. Fruits were stored at 24 ± 2 °C for 11 days and evaluated for weight loss, pulp and peel firmness, soluble solids, pH, titratable acidity, and peel color. MAC exhibited a specific surface area of 804.29 m² g⁻¹ and a phenolic adsorption efficiency above 80%, while the bioactive films showed an antioxidant capacity approximately 6.5-fold higher than that of the control film. Films containing emulsion and/or MAC reduced weight loss to 7.59-11.49%, compared with 15.26% in unpackaged fruits, and maintained pulp firmness at 0.37-0.61 N versus 0.19 N. Soluble solids remained at 6.6-7.6 °Brix in fruits packaged with emulsion- and carrier-containing films, whereas PVA-packaged and unpackaged fruits reached 23.3 and 25.6 °Brix, respectively. Maintenance of firmness, soluble solids, and green peel color indicated delayed ripening, mainly due to the packaging barrier effect. These results demonstrate the potential of these films as sustainable active packaging for banana postharvest preservation.