Gelatin/sodium alginate multilayer composite film crosslinked with green tea extract for active food packaging application

With the increasing environmental concern and consumption demand for fresh food of human being, development of biodegradable and active food packaging films is highly desirable. In this study, an active multilayer food packaging film was fabricated using gelatin (GEL) and sodium alginate (ALG) as matrix biopolymer, green tea extract (GTE) derived from green tea waste as cross-linking agent and active ingredient. The film-forming method was based on simple layer-by-layer (LBL) casting. SEM and FTIR demonstrated the good compatibility of the film-forming substances and the formation of a more compact LBL multilayer composite film due to occurrence of increased intermolecular hydrogen bonding, thereby improving UV-shielding, mechanical strength, water vapor and oxygen barrier, water resistance and thermal stability. The multilayer composite film also exhibited high antioxidant and antibacterial activity. Particularly, slow release of GTE from multilayer composite film was observed. Moreover, the preservation study demonstrated that obtained active film could effectively maintain postharvest quality of Boletus bicolor Peck and extend shelf-life to 7 days under 4 °C storage, indicating its promising application potential for food preservation.