Preparation of curcumin-chitosan composite film with high antioxidant and antibacterial capacity: Improving the solubility of curcumin by encapsulation of biopolymers

Curcumin is a kind of natural antioxidant antibacterial agent, but the poor water solubility and stability limit its application in the field of food packaging. To solve this problem, dialdehyde starch-curcumin-gelatin particles (hereafter denoted as DCG particles) were prepared by wrapping curcumin into the cross-linked body formed by dialdehyde starch and gelatin. The strong hydrophilicity of the outer cross-linked body increases the water solubility of curcumin by 3162.7% from 0.43 μg/mL to 13.6 μg/mL. DCG particles were added to chitosan to form a composite film to evaluate the application of the particles. The Chromogenic group and phenolic hydroxyl group in curcumin endowed the composite film with good ultraviolet resistance and antioxidant capacity, which could shield 94.48% of ultraviolet radiation, and the free radical clearance rate reached 99%. Besides, chitosan and curcumin can destroy bacterial cell film and inhibit bacterial division and proliferation. The inhibition zone of composite film against E. coli and S. aureus was 21.4 mm and 19.9 mm, and the cell survival rate treated with film solution was 113.16%. The weight loss rate and decay rate of fruit soaked in film solution were 60% and 10% compared with untreated fruits, respectively. Overall, this study advanced a novel method for improving the water solubility of curcumin and making natural food packaging materials.