Research Progress of Composite Films in Postharvest Preservation of Fruits and Vegetables

Fruits and vegetables are vulnerable to enhanced respiratory metabolism, water loss, enzymatic browning, and microbial invasion during postharvest storage and transportation, leading to spoilage and reduced shelf life. Traditional preservation methods, such as physical, chemical, and single-component film technologies, offer limited benefits due to their single function and instability. Composite films, however, show great promise in postharvest preservation by integrating the strengths of different substrates and active components. This review discusses the research progress of composite films in preserving fruits and vegetables, covering their definition, classification, and key performance characteristics. It also examines the functional roles of substrates like polysaccharides, proteins, and lipids, and explores the mechanisms of composite films, including gas regulation, metabolic inhibition, water retention, antimicrobial effects, antioxidant activity, and browning delay. Additionally, it compares the applications of composite films in whole and fresh-cut fruits and vegetables. Current research highlights the shift from general applications to targeted designs based on the unique deterioration mechanisms of different produce. Future studies should focus on optimizing the matching between product characteristics and film design, advancing composite films towards safer, more stable, and practical applications.