Development of sustainable packaging films using hybrid food-processing waste starches reinforced with recycled cotton cellulose fibers

This study demonstrates a sustainable, multi-waste-derived approach to fabricating biodegradable composite biofilms by simultaneously valorizing three independent household and industrial waste streams: potato peel waste, industrial rice milling residue, and short recycled textile cotton fibers. Using a scalable solution gelatinization and compression molding technique assisted by a food-grade glycerol and acetic acid system, a hybrid starch matrix was developed and reinforced with varying fiber concentrations. The structural and functional properties of the resulting biofilms were profoundly dictated by the fiber loading level. The integration of 10% recycled cotton fiber established an optimal reinforcement network, boosting the tensile strength by over 240% to a peak of 5.2 MPa compared to the unreinforced matrix. Furthermore, strong matrix-fiber interfacial hydrogen bonding locked the hydrophilic polymer chains, reducing water solubility from 45% down to 12% at maximum loading. While the unreinforced thermoplastic starch films underwent rapid aqueous disintegration within 36 hours, the high-density fiber mesh successfully acted as a structural cage, maintaining macrostructural integrity for up to 120 hours. Finally, soil-burial testing confirmed exceptional environmental compatibility, with all films undergoing heavy microbial fragmentation and achieving full metabolic consumption within 28 to 35 days, presenting a highly viable, closed-loop packaging alternative aligned with circular bioeconomy goals.