Curcumin-based waterborne polyurethane-gelatin composite bioactive films for effective UV shielding and inhibition of oil oxidation

Introducing natural products to obtain ultraviolet (UV) shielding materials for inhibiting the photo-oxidation of oily foods is environmentally friendly food technology. Instead of traditional physical mixing, curcumin was introduced into castor oil-based waterborne polyurethane as a chain extender and compounded with gelatin for bioactive composite films. With the increase of curcumin-based waterborne polyurethane (CWP), the film with 10 wt% CWP achieved nearly complete ultraviolet shielding. The swelling index and water solubility were reduced by 800% and 12.93%, respectively. The tensile strength and elongation at break increased by 183% and 114%, respectively. In addition, CWP enhanced the antioxidant activity of curcumin in water system by 52.10% and reduced the oxidation degree of soybean oil by 62.03–87.84%. This work provides a new idea for compounding natural active small molecules with polymers.