Molecular assembly, preservation mechanisms, and water transfer behavior of biopolymer-based films/coatings for fruits and vegetables and a focus on konjac glucomannan.

Fruits and vegetables (FVs) are indispensable dietary resources with rich nutrition, yet their postharvest quality deterioration, rapid water loss, microbial decay, and vigorous physiological metabolism severely limit shelf life and market supply. As eco-friendly, biodegradable, and edible preservation materials, biopolymer-based films/coatings have become a research hotspot in the postharvest field, among which konjac glucomannan (KGM) stands out owing to its excellent film-forming property and biocompatibility. This review comprehensively elaborated the research progress of biopolymer films/coatings for FV preservation, innovatively clarifying the molecular assembly (polysaccharide-polysaccharide, polysaccharide-protein, polysaccharide-lipid, protein-lipid, and other multicomponent systems), water transfer dynamic behavior, and advantages and defects of different KGM-based modified films/coatings. Subsequently, the microstructure, film-forming properties, and KGM-based films/coatings were deeply analyzed, highlighting the performance optimization and preservation applications of KGM-based films/coatings via blending modification, nanoparticle reinforcement, and active ingredient loading. Moreover, the water transfer rules among FVs, films/coatings, and the storage environment, as well as the multi-mechanisms of FV preservation (barrier, antimicrobial and antioxidant effects, induce systemic resistance, and intelligent freshness indication) were discussed in depth. Current studies verify that KGM-based films/coatings can effectively regulate gas and water vapor exchange, inhibit microbial reproduction, delay physiological senescence, and reduce nutrient loss, thereby significantly extending the shelf life of various FVs. This review would provide theoretical reference and technical support for the assembly design, preservation regulation, and industrial application of high-performance KGM-based preservation materials.