Incorporation of aminated starch-polyphenol conjugates to improve corn starch film properties

Incorporation of aminated starch (AS)-polyphenol conjugates to improve corn starch (CS) film properties were explored. AS-polyphenols (gallic acid (GA), syringic acid (SA) and vanillic acid (VA)) conjugates were synthesized by laccase and the grafting rates of GA, SA and VA were 36.59, 69.71 and 68.85%, respectively. Incorporation of the three conjugates (AS-GA, AS-SA and AS-VA) into the corn starch film improved a variety of properties of the CS film. The CS film without the conjugates was smooth and flat, while surface of the CS film with the conjugates became relatively rough and wrinkled and there were some small particles on the surface. Incorporation of the conjugates improved the thermal stability of the CS film during the polymer depolymerization phase. The thickness of the CS film with AS-VA conjugates was significantly larger than that of the CS film and the incorporation of the conjugates improved the hydrophobicity of the CS film. The tensile strength (TS) of both the CS films with AS-GA conjugates and AS-VA conjugates was significantly enhanced, while the TS of the CS film with AS-SA conjugates was significantly reduced. The incorporation of AS-polyphenol conjugates could improve the antioxidant ability and antibacterial ability of the CS film, especially the CS films containing AS-GA conjugates.