Characterization of physical, mechanical, and antioxidant properties of soy protein-based bioplastic films containing carboxymethylcellulose and catechin

The aim of this study was to develop functional bioplastic materials for food packaging by incorporating a natural antioxidant agent into soy protein-based films. The film formulations were composed of soy protein isolate (SPI) in combination with carboxymethylcellulose (CMC) and/or catechin (CT). The original SPI film exhibited a good optical transparency, whereas it turned opaque after being blended with CMC or CT. The SPI film spiked with CMC showed enhanced water solubility and tensile strength, and decreased water vapor permeability and percentage elongation, as compared with pure SPI film. However, the oxygen permeability of the film was barely influenced by the addition of CMC. Furthermore, the CT-incorporated SPI or SPI/CMC films demonstrated a synergistic freeradical scavenging effect. The results suggested that the soy protein-based bioplastic film developed in this study could be used as a potent antioxidant packaging material in the food industry.