Edible chitosan–rice husk cellulose nanocrystal films and coatings with cinnamon vs. lemongrass essential oils: antifungal efficacy for mango anthracnose under tropical ambient storage

Abstract

This study developed edible biocomposite films from chitosan–rice husk cellulose nanocrystals (CS–CNCs) with cinnamon essential oil (CEO) or lemongrass essential oil (LEO) (0.5–3% w/w). Films were characterized for physicochemical and antimicrobial properties, and coatings were assessed on inoculated mangoes under ambient tropical storage (32 °C). The presence of essential oil (EO) significantly increased film antioxidant activity, total phenolic content and antimicrobial properties. However, the tensile strength of the CS–CNC biocomposite films decreased from 19.39 ± 1.84 MPa to 4.54 ± 0.81 MPa at 3% CEO and to 1.62 ± 0.58 MPa at 2% LEO, and the elongation at break decreased from 12.07% ± 1.28% to 7.34% ± 0.67% and 2.49% ± 0.79%, respectively. Notably, 3% CEO improved the water vapour permeability (1.49 ± 0.16 g mm kPa⁻¹ h⁻¹ m⁻²) of films compared with both the control film (without EO) (2.21 ± 0.05 g mm kPa⁻¹ h⁻¹ m⁻²) and the 2% LEO containing film (2.41 ± 0.19 g mm kPa⁻¹ h⁻¹ m⁻²). The CS–CNC-EO film-forming solutions demonstrated 100% mycelial growth inhibition of Colletotrichum gloeosporioides at ≥1% CEO and 2% LEO in vitro. When applied to mangoes, the coating treatments significantly retarded disease severity in inoculated fruits compared with the uncoated controls during storage. CS–CNC biocomposite films incorporated with 0.5% (w/w) CEO or LEO are effective in the reduction of the anthracnose disease of mango. Future development should focus on improving the sensory properties, controlling ingredient migration, and addressing scalability for industrial food packaging applications that can be adapted to other perishable fruits beyond mangoes while ensuring regulatory compliance and consumer acceptance.