Preparation of tannic acid-modified fish scale gelatin/polydopamine photothermal film and its application in cherry tomatoes

TA was compatible with the PDA NPs/FSG and formed cross-linked network. • TA/PDA NPs/FSG film exhibited enhanced mechanical and barrier properties. • TA/PDA NPs/FSG film exhibited stable and superior photothermal performance. • TA/PDA NPs/FSG film extended cherry tomatoes shelf life under NIR irradiation. Fish scale gelatin possessed favorable film forming properties. However, its practical application was limited by inadequate antibacterial activity and suboptimal physical characteristics. This study modified FSG with tannic acid (TA) to enhance its physical properties and incorporated polydopamine nanoparticles to impart photothermal antibacterial functionality. Tannic acid/polydopamine nanoparticle/fish scale gelatin (TA/PDA NPs/FSG) photothermal films were readily obtained using a straightforward casting method. SEM indicated that TA modification reduced cross-sectional cracking in the films. FTIR and XRD confirmed that the modified gelatin primarily was primarily driven by hydrogen bonding interactions between the phenolic hydroxyl groups of TA and the hydroxyl groups in gelatin. The 5% TA/PDA NPs/FSG film demonstrated significantly enhanced physical properties compared to the unmodified control. It mainly included a 42.73% reduction in water vapor permeability, a 55.14% decrease in air oxygen transmission rate, a 72.11% increase in elongation at break and a 48.73% reduction in tensile strength. Furthermore, TA incorporation improved the photothermal performance, enabling the 5% TA/PDA NPs/FSG film to rise by 77.4 °C under 808 nm near-infrared irradiation. In packaging freshness tests, it was found to maintain the fresh appearance, weight, firmness and soluble solids content of cherry tomatoes, thereby extending the shelf life. Download: Download high-res image (253KB) Download: Download full-size image