The preparation of fish scale gelatin-polydopamine photothermal sterilization film and its application for storage of cherry tomato

In this study, polydopamine nanoparticles (PDA NPs) were synthesized and fish scale gelatin (FSG) was extracted by hot water hydrolysis. The film for photothermal sterilization was created by casting FSG with the addition of PDA NPs. The results indicated that the PDA NPs were able to heat up to 46 °C in 5 min under near-infrared (NIR), demonstrating good photothermal conversion. The PDA NPs/FSG solution showed short-term bactericidal activity against Staphylococcus aureus and Escherichia coli, with a bactericidal rate of more than 99 %. The PDA NPs/FSG film could warm up to 42.6 °C under NIR irradiation for 5 min. With the addition of 0.3 % of PDA NPs, the PDA NPs/FSG films showed high UV absorption, DPPH and ABTS radical scavenging ability, and high water contact angle (WCA), improving the barrier to water and oxygen and the tensile strength. The 0.3 % PDA NPs/FSG film triggered by NIR effectively maintained the firmness, soluble solids content and appearance, and delayed the weight loss of cherry tomatoes. Thus, the PDA NPs/FSG films had good photothermal antimicrobial activity and could be used for extending the shelf life of cherry tomatoes.