Preparation of a high-strength, antibacterial, and biodegradable bio-based film through amide crosslinking and nano-reinforcement for fruit packaging

Confronted with the persistent environmental challenge posed by non-degradable petroleum-based plastics, biodegradable bio-based plastics have emerged as a promising research focus. However, current materials are often limited by inadequate mechanical strength and susceptibility to mildew. To overcome these limitations, this study innovatively developed a novel bio-based film (C-g-SPT) by integrating polyethyleneimine (PEI) and nano titanium dioxide (TiO 2 ) into a carboxymethyl cellulose (CMC)/soy protein isolate (SPI) composite system. Through amidation reactions and network formation, a stable three-dimensional structure was constructed. The resulting composite film exhibits exceptional properties: maximum tensile strength of 17.31 MPa (14 times higher than SPI film); elongation at break of 59.19 % (27.92 % higher than CMC film). In addition, the mold resistance period has been extended from 5 days to over 24 days; and the modified film can be completely degraded within 64 days. Furthermore, it significantly extends strawberry shelf life to 10 days, outperforming traditional polyethylene (PE) packaging by 5 days. This study provides an innovative strategy for developing high-performance, cost-effective, and biodegradable bio-based films, advancing their industrial application and sustainable development.