Biopolymers in Nanocoating: Principles and Applications

Nanocoating technology has emerged as a transformative strategy for enhancing the functional properties of food materials, packaging substrates, and food contact surfaces. This review explores the role of biopolymers as coating materials in nanocoating applications, with a particular focus on the food sector. Inorganic nanomaterials such as silver, titanium dioxide, zinc oxide, and silicon dioxide have been extensively studied for their antimicrobial, photocatalytic, and barrier-enhancing properties; however, concerns regarding toxicity and regulatory compliance continue to limit their direct food contact applications. Biopolymer-based nanocoatings present a safer and more sustainable alternative, offering biodegradability, biocompatibility, and GRAS (Generally Recognized as Safe) status. Key application areas reviewed include edible coatings for fresh and minimally processed fruits, vegetables, meat, cheese, and mushrooms; nanocoating of paper-based and polymeric packaging materials to improve gas barrier, mechanical, moisture resistance, and antimicrobial properties; nanocoating of glass or metal containers and active packaging systems, and nanocoating of food contact surfaces to prevent biofouling and microbial contamination. Recent studies confirm that biopolymer-based nanocoatings, particularly those based on chitosan, cellulose nanofibers, and alginate, can significantly extend shelf life, reduce weight loss, retard oxidation, and maintain sensory quality. Migration of nanomaterials from coatings into food systems is identified as a key safety concern. Challenges including scalability, coating durability, substrate compatibility, and incomplete toxicological profiling are critically discussed. This review underscores the need for standardized testing protocols, comprehensive regulatory frameworks, and continued research into durable, food-grade biopolymer nanocoatings as viable replacements for conventional synthetic coating systems in food preservation and packaging.