Papaya ‐Leaf‐Assisted Fermentation for Enhanced Extraction of Cassava Peel Starch and Its Application in Biodegradable Films

Abstract

ABSTRACT Cassava peels, an agro‐industrial residue, were valorized as a second‐generation starch feedstock for starch‐based films. Starch was extracted by papaya ‐leaf‐assisted fermentation, non‐assisted fermentation, and direct extraction; fermented cassava served as a first‐generation benchmark. Papaya ‐leaf‐assisted fermentation gave the highest peel‐derived starch yield (38 wt% dry basis), exceeding non‐assisted fermentation (30%) and direct extraction (27%), although it remained lower than that of fermented cassava (68%). The starch obtained from peels by direct extraction showed the highest nitrogen content, indicating limited removal of nitrogenous residues, whereas fermentation reduced residual nitrogen, and papaya ‐leaf‐assisted fermentation produced the lowest nitrogen among peel‐derived starches. Scanning electron microscopy showed larger, smoother granules for the papaya ‐leaf‐fermented starch, and thermogravimetric analysis indicated superior thermal stability. All starches showed similar infrared profiles and A‐type x‐ray diffraction features (15°, 17°, 18°, 23°; 2θ). Based on yield and quality, the papaya ‐leaf‐fermented starch was plasticized with glycerol and acetic acid to cast films. Film infrared spectra and x‐ray diffraction results indicated disrupted hydrogen bonding and loss of A‐type crystallinity, while solubility and absorption tests confirmed hydrophilic behavior. Soil‐burial tests showed rapid, moisture‐dependent biodegradation, with complete disintegration under the wettest condition within 12 days. A practical route to biodegradable films from a second‐generation starch source was proposed.