Nanostructured starch-based films incorporating essential oil and nerolidol-loaded nanoparticles for postharvest protection of strawberries

Strawberries are highly perishable due to their soft texture, high moisture content, and susceptibility to microbial contamination, particularly by Botrytis cinerea. This study developed and characterized starch-based films containing nanoparticles (NPs) loaded with Baccharis dracunculifolia essential oil (EO) or nerolidol (NE) and evaluated their effectiveness in extending strawberry shelf life. Three films were produced: a control film (CF) without antimicrobials, and films containing EO-loaded (NP-EO-F) or NE-loaded (NP-NE-F) NPs. Physical, mechanical, and structural analyses showed that NP incorporation reduced moisture content and water vapor permeability, while enhancing tensile strength and Young's modulus of the films, indicating improved barrier and mechanical properties. Cross-section SEM images showed a heterogeneous structure and porous regions in films incorporating NPs, while AFM analysis revealed that CF presented the highest values of roughness parameters. DSC thermograms showed broad, shallow endothermic peaks indicating a predominance of amorphous structures. The films were applied to strawberries stored under refrigeration for 10 days. Fruits treated with NP-EO-F and NP-NE-F exhibited a lower weight loss, higher firmness, and greater retention of phenolic compounds compared to controls. Color preservation was also superior in NP-treated groups, with a lower ΔE value. Regarding antifungal performance, uncoated fruits and those coated with CF showed extensive fungal decomposition, whereas NP-EO-F provided the strongest protection, with some fruits showing no visible deterioration. These nanostructured starch-based films effectively preserved strawberry quality and offered strong antifungal activity, representing a sustainable alternative to synthetic fungicides.