Green-processed lignin nanoparticle/chitosan composite films for enhanced preservation of cherry tomatoes

This study rapidly isolated lignin from wheat straw by constructing several ternary eutectic solvent systems, followed by preparing lignin nanoparticles (LNPs) via an ultrasonic-assisted antisolvent method. Subsequently, LNPs of varying concentrations and types were incorporated into a chitosan (CS) matrix. A series of LNP/CS composite films was prepared by the cast-film method and applied to the preservation of cherry tomatoes. Results revealed that LNP incorporation significantly enhanced the composite film's overall performance. Compared to pure CS films, LNP/CS composites demonstrated superior water resistance, UV barrier properties, mechanical strength, thermal stability, antioxidant capacity, and antibacterial activity. Among these, the composite film incorporating 20 % LNPs prepared from choline chloride/1,4-butanediol/aluminum chloride (CBA-LNPs) exhibited the most optimal overall performance. Subsequently, this composite film was applied to studies on cherry tomato preservation. Results demonstrated that coating with the CBA-LNPs/CS composite film effectively mitigated quality deterioration during storage, with the optimal preservation efficacy observed at an LNPs content of 20 %. Following 14 days of refrigerated storage at 4°C, the 20 % CBA-LNPs/CS-coated group maintained the most intact appearance and color compared to the untreated group. Its spoilage rate and weight loss rate were reduced by 63.15 % and 28.72 %, respectively, whereas firmness was increased by 117.76 %. Additionally, this treatment effectively retarded the loss of titratable acidity and vitamin C content. In summary, LNP/CS composite films demonstrate broad potential as novel bio-based materials for food preservation.