Castor oil-based waterborne polyurethane photodynamic antimicrobial films: Preparation and strawberry preservation application.

This study synthesized anionic castor oil-based waterborne polyurethane (WPU) and cationic quaternized cellulose nanofiber (CCNF), and encapsulated curcumin (Cur) with hydroxypropyl-β-cyclodextrin (HP-β-CD) to form a Cur inclusion complex (CD). CD/CCNF/WPU composite films with water resistance and photodynamic antimicrobial properties were then prepared via solvent casting by blending WPU, CCNF and CD before casting. For the 6%CD/CCNF/WPU film, the CO2/O2 gas separation coefficient was 4.04 and the water vapor transmission rate was 21.93 g/(m2·24 h). After 60 min of blue-light irradiation (550.8 J/cm2), its inhibition rates against Escherichia coli and Staphylococcus aureus reached 76.93% and 96.45% respectively. These properties synergistically promoted strawberry preservation. The CO2/O2 gas separation coefficient maintained a respiration-inhibiting gaseous environment (8.5-9.5% O2, 13.1-14.5% CO2), while photodynamic antimicrobial properties suppressed microbial growth. This effectively prolongs strawberry shelf life to 15 days (10 °C, 90% relative humidity). With photodynamic antimicrobial function, the CD/CCNF/WPU film exhibits broad application prospects in fruit and vegetable preservation.