Biodegradable active edible films from ora-pro-nobis mucilage enriched with natamycin for fungal growth control

Vegetal mucilages, such as that of Pereskia aculeata (ora-pro-nóbis, MOPN), have been explored as biodegradable film-forming matrices with barrier properties, and when combined with natamycin, they constitute a promising strategy for controlling fungi in food. This study aimed to develop and characterize starch-based films containing ora-pro-nobis (MOPN), with and without natamycin, and to evaluate their antifungal activity against Penicillium expansum . The mucilage was obtained by aqueous extraction and the films were produced by casting with cassava starch and glycerol; physicochemical characterizations (CIELab, thickness, UV–Vis, FTIR-ATR, water solubility, and swelling), microstructural characterizations by SEM, and microbiological tests (agar diffusion, time-kill at 0–72 h, and spore germination at 0–48 h) were performed. The films exhibited a thickness of 0.120–0.135 mm; the incorporation of MOPN and MOPN + natamycin reduced transparency (λ380: 6.48% and 3.53%; λ600: 14.46% and 12.51%) compared to the control, increased solubility (16.33%-39.42%), and enhanced swelling (131.46%→382.94% with MOPN; 311.47% with MOPN+natamycin). The UV-Vis spectra indicated an efficient barrier to UV radiation; the FTIR evidenced hydrogen-bond interactions between MOPN/natamycin and the starch matrix; and the SEM revealed rougher surfaces and agglomerates in the films containing MOPN. In microbiological tests, isolated MOPN did not form an inhibition halo, whereas MOPN + natamycin formed an inhibition zone, suppressed germination, and promoted eradication of growth within 72 h in the time-kill assay. It is concluded that starch films enriched with MOPN and natamycin combine photo-oxidative protection with effective antifungal activity against P. expansum , making them a promising biodegradable alternative for active food-contact edible films.