Polyethylene/Hydrophobic Calcium Lignosulfonate Composite Film for Anti‐Photooxidation of Fuji Apples

ABSTRACT Excessive ultraviolet (UV) radiation exposure induces photooxidative stress in plants, leading to severe cell damage. Current packaging films often rely on nonrenewable, petroleum‐based UV absorbers, which may pose potential health risks. Calcium lignosulfonate, a natural byproduct derived from the pulp and paper industry, has attracted significant attention as a sustainable alternative to petroleum‐based UV absorbers. In this study, calcium lignosulfonate was hydrophobically modified to enhance its compatibility with nonpolar low‐density polyethylene (LDPE), and a UV‐blocking composite film was subsequently fabricated. The hydrophobic modification significantly increased the water contact angle of calcium lignosulfonate from 5° to 101°. Incorporating the modified calcium lignosulfonate into LDPE improved both the melting point and crystallinity of the polymer. The resulting composite film demonstrated excellent UV‐blocking performance, achieving a UV‐A blocking rate of 95% and a UV‐B blocking rate of 99%, and effectively mitigated photooxidative browning in “Fuji” apples. This film exhibits great potential for anti‐photooxidation packaging applications while simultaneously reducing dependence on petroleum‐based resources.