Photothermal Carbon Nanoparticles-Cellulose Nanocrystal Nanocomposite Films and Their Application in Enhancing Fruit Preservation

This study aimed to investigate the synergistic effect of photothermal films comprising carbon nanoparticles (CNPs) and cellulose nanocrystals (CNCs) in extending the shelf life of kiwifruit. Herein, a novel nanocomposite was synthesized via photothermal synergism by introducing CNPs into CNCs using ultrasonic assembly methods and the resulting composition was mixed with a polyvinyl alcohol (PVA) matrix to develop PVA based films. Results showed that the optimal ratio of CNPs to CNCs was 1:4 for the CNP/CNC composites. The CNPs/CNCs composites mainly bonded through hydrogen bonds and exhibited favorable thermal stability. The mechanical strength of the PVA based films added with 0.2% CNP/CNC composites improved by 79% compared with that of pure PVA films. Water vapor permeability of PVA-based films added with 0.2% CNP/CNC composites reduced by 8%, consistent with the water contact angle results. Notably, the addition of CNPs/CNCs composites to PVA films achieved superior photothermal effects, with the temperature increasing to 76.2°C during 1 min of irradiation, which is 48% higher than that of pure PVA films. Moreover, the addition of CNPs/CNCs composite to PVA films effectively reduced the weight loss and maintained the hardness, pH, and total soluble solid content of kiwifruit during storage. The addition of the CNPs/CNCs composite also delayed the decay time of kiwifruit by 3 days, presenting a novel approach for fruit preservation.