Food-derived biopolymer kefiran composites, nanocomposites and nanofibers: Emerging alternatives to food packaging and potentials in nanomedicine

Abstract Background Kefiran is an exopolysaccharide derived from microflora of kefir grains presented in a fermented milk beverage. It has gained researchers' attention due to its biological properties, biocompatibility, film-forming and electrospinning abilities, highlighting its tremendous potential in applications from food packaging to nanomedicine. Scope and approach Herein, we provided a comprehensive review with state-of-the-art composites, nanocomposites and nanofibers based on kefiran useful in food and medical applications. Once kefiran films are naturally brittle, this overview focuses on a structure-properties relationship to understand how other nanostructures and elements can overcome challenges and improve properties required for biodegradable food packaging materials (e.g., water resistance, barrier, and mechanical properties). Key findings and conclusions: Recent progress showed kefiran combined with other polymers as whey protein isolate and waterborne polyurethane, essential oils (EO) and nanofillers as nanocellulose, zinc oxide and alumina nanoparticles with barrier and mechanical properties equivalent or better to synthetic polymers used as standard packaging materials. Moreover, depending on the content added, EO can provide plasticizing effect or reinforcement of interphase in kefiran nanocomposite, adding new functionalities (e.g., UV-protection, antioxidant and antimicrobial features), highlighting its potential in active food packaging. Besides that, migration testing can fill critical gaps and provide progress in the field. Recent advances in kefiran also showed its electrospinning ability to be transformed in nanofiber, potentially useful to encapsulate bioactive ingredients to food, probiotic/drug delivery and scaffolds to tissue engineering. Besides, challenges, current trends and perspectives of these kefiran nanomaterials considering their safety and regulation concerns are also identified and discussed.