Sustainable nanocoatings for agricultural produce: A biodegradable approach using cellulose nanomaterials and pectin from sweet potato peel

Sweetpotato (SP) is one of the world's most important, versatile, and underexploited foods. However, the quality and nutritional composition of sweetpotato roots (SPRs) can rapidly deteriorate under adverse postharvest conditions. Improving the postharvest quality and storability of SP is essential. This study focuses on extracting and characterizing cellulose nanomaterials (CNMs), pectin, and phenolic compounds from sweetpotato peel (SPP) as components for bio-based coatings using an eco-friendly approach. SPP was found to contain cellulose (40.23 %), lignin (19.12 %), hemicellulose (10.81 %), and pectin (19.84 %). Anthocyanin extracts exhibited pH-sensitive color changes and antioxidant activity. The extracted CNMs displayed high crystallinity (85 %), particularly for cellulose nanocrystals. Rheological studies revealed that CNMs and pectin suspensions exhibited shear-thinning and viscoelastic properties, making them suitable for coatings. The total phenolic content and antioxidant activity were 7.3 and 6.8 mg gallic acid equivalent/g, respectively. Ethanol extraction showed higher antioxidant efficiency (22.8 mg Trolox equivalents/g). Nanocoatings containing CNMs, pectin, phenolic compounds, and essential oils reduced respiration rates by up to 72 % and minimized weight loss by 51 % compared to uncoated controls. This work demonstrates the potential of valorizing SPP for sustainable coatings to extend SPR's shelf-life and quality.