Antifungal edible coatings for postharvest preservation of fresh fruit

Abstract

Postharvest losses of fresh fruit are mainly caused by weight loss, physiological disorders, and decay during storage and commercialization. Currently, postharvest treatments with conventional chemical fungicides and/or synthetic waxes are commonly used in combination with low-temperature storage to reduce such losses and minimize their economic impact. However, their continuous use by the industry for many years has arisen important health and environmental problems related to the production of chemical residues and the proliferation of resistant pathogenic fungal biotypes. Therefore, safe and eco-friendly alternatives should be commercially implemented as part of non-polluting integrated disease management (NPIDM) programs for preservation of fresh fruit. Among them, the development of edible coatings with antifungal activity is a technological challenge and a very active research field worldwide. The main advantage of these coatings is that they could provide a single solution for both physiological and pathological major postharvest issues. While some natural coatings such as chitosan or Aloe spp. gels show inherent antifungal activity, specific food-grade antifungal ingredients should be incorporated into composite matrixes of hydrocolloids (polysaccharides such as cellulose derivatives, alginates, pectins, gums, and peptides or proteins) and lipids to form synthetic edible coatings with antifungal properties. These ingredients include natural or low-toxicity compounds, such as inorganic or organic salts (e.g., carbonates, sorbates, benzoates, paraben salts) and essential oils or other plant extracts approved as food additives or generally recognized as safe (GRAS) compounds by competent authorities, and biological control agents such as antagonistic strains of some microorganisms.