Mycotoxins in harvested fruits and vegetables. Insights in producing fungi, biological role, conducive conditions, and tools to manage postharvest contamination

The postharvest life of fruits and vegetables is influenced by several parameters, such as physiological properties and biotic/abiotic stresses. In particular, a consistent portion of the product is lost, mainly due to fungal diseases, which represent a concern not only to retailers but also to consumers, due to the presence of mycotoxins. Indeed, some species of postharvest genera, i.e. Aspergillus, Penicillium, and Alternaria, produce toxic secondary metabolites, which pose a health risk to humans and animals, so that maximum content in harvested commodities and derived products have been established for certain toxins by national and international organizations. Although some mycotoxins are poisonous to competing microorganisms or plants, their biological role is still unclear. Recent studies support their involvement in disease onset/development, so that a reduction in mycotoxin production might have a disease control perspective. Indeed, the use of synthetic fungicides is not always possible or effective in postharvest, because of restrictions on residue content and the appearance of resistant strains. Moreover, the application of suboptimal concentrations of fungicides may even increase mycotoxin biosynthesis. Thus, the demand for alternative control means (e.g. microbial antagonists, natural or generally regarded as safe compounds, and physical means) is growing. In this review, a synopsis of the main postharvest mycotoxigenic genera is given with particular reference to their control.