A second life for fruit and vegetable waste: a review on bioplastic films and coatings for potential food protection applications

In recent decades, significant progress has been made on the development of low environmental impact plastic materials, as alternatives to conventional plastics for food packaging. Research has focused on the engineering of renewable resources of animal or vegetable origin that are rich in polysaccharides and proteins, to produce green bioplastic materials for food packaging, with good mechanical and gas barrier properties. Furthermore, incorporating natural antimicrobials, antioxidants, and pH-sensitive substances in the new eco-friendly materials, smart and active green packaging can be developed. Recently, the preparation of bioplastics and biocomposites directly from the processing of agro-food residues via hydrolysis or digestion was proposed for the production of new added-value products that comply with zero waste and circular economy principles and are expected to impact the future of food packaging significantly. This review aims to revise the various fruit and vegetable agrowaste-based bioplastic and biocomposite systems developed so far, with potential applications in food protection and shelf life extension. The vegetal lignocellulosic and non-lignocellulosic agrowaste composition, processing methods, and properties of the developed biomaterials are addressed. The obtained biocomposites, rich in natural polymers, as cellulose, pectin, starch, zein, etc., can actively protect the packaged food against oxidation or microorganisms, as long as they preserve the raw materials’ phytochemicals in their composition. We focus on simple and easily scalable procedures that either involve green solvents or require low-energy, and lead to films for food packaging or suspensions intended to be applied as coatings directly on fruit or other foodstuff surfaces. All the previously mentioned aspects are extensively reviewed in this manuscript, mainly considering the literature reported during the last five years including the research works of the authors in the field.