Functional additives to strengthen composite packaging film containing cellulose nanocrystals: Property enhancement and applications in food preservation

Petroleum-based polymers have significantly contributed to modern convenience. However, their non-biodegradable nature has led to severe environmental pollution. Cellulose nanocrystals (CNC) have emerged as a novel matrix for eco-friendly packaging materials due to their unique advantageous properties. Furthermore, as technology advances, consumer demands for packaging materials have evolved, requiring enhanced functionality, sustainability, and safety. CNC, derived from native cellulose, exhibit not only superior biodegradability and biocompatibility but also demonstrate high crystallinity and mechanical toughness, thereby significantly enhancing the performance characteristics of composite films. When incorporated into composite systems, CNC form a three-dimensional network structure capable of immobilizing various functional additives—such as inorganic metal nanoparticles or bioactive plant-derived compounds. This uniform dispersion within the matrix imparts advanced functionalities to the resulting films, including antimicrobial and antioxidant properties, while also enabling sustained release mechanisms that prolong their functional lifespan. This review systematically examines the extraction methodologies of CNC, the variety of functional additives incorporated into CNC, and their subsequent impacts on film characteristics. Furthermore, this review summarizes the applications of CNC-enhanced packaging materials in the food industry. CNC-reinforced composite packaging films incorporated with functional additives demonstrate significant potential for use in edible packaging, biodegradable materials, and intelligent packaging systems.