Edible interfaces based on chitosan, cellulose, and hemicellulose: from food preservation to bioactive delivery and post-consumption relevance.

The increasing demand for sustainable, functional, and safe food packaging has driven the development of edible polysaccharide-based films and coatings. Cellulose, hemicellulose, and chitosan serve as versatile platforms for constructing multifunctional interfaces that integrate preservation, bioactive delivery, and post-consumption functionality. This review systematically examines strategies to enhance mechanical strength, barrier performance, water resistance, and controlled release through nanoreinforcement, polymer blending, plasticization, crosslinking, and processing optimization. Active preservation functions, including antimicrobial, antifungal, and antioxidant activities, are contextualized with real food applications such as fruits, vegetables, meat, dairy, and lipid-rich products. Special attention is given to bioactive loading and controlled release of phenolics, flavonoids, essential oils, probiotics, and prebiotic xylooligosaccharides, while critically distinguishing formulation-level evidence, such as release in food simulants or simulated gastrointestinal fluids, from unvalidated claims of gut microbiota modulation or nutritional benefit. Food matrix-specific validation illustrates how interface design must match the dominant spoilage pathways of target foods. The post-consumption fate and microbiota-oriented relevance of edible films are discussed as emerging possibilities, with emphasis on the current lack of direct colonic fermentation, animal, or human intervention evidence for many reported systems. Furthermore, advances in intelligent, responsive, and self-healing edible interfaces are explored, along with safety, edibility, sensory acceptability, regulatory considerations, and industrial scalability. Finally, design guidelines for next-generation edible food interfaces are proposed, integrating material selection, polymer engineering, active cargo design, and nutrition-oriented validation. This comprehensive framework provides a roadmap for developing edible interfaces that can improve food quality and sustainability while supporting future investigation of their nutrition-related and post-consumption relevance.