Ochratoxin A in grapes: manage of risk and new evidence in climate change scenario

Ochratoxin A (OTA) is a potent pentaketide nephrotoxin diffusely distributed in food and feed products (grains, legumes, coffee, dried fruits, meats, beer and wine); it is also carcinogenic, neurotoxic, teratogenic and immunotoxic. This mycotoxin is produced by species of genus Aspergillus and Penicillium. OTA is the primarily mycotoxin risk in wine and dried vine fruits. Several studies focused on Aspergillus section Nigri, due to their role as causative agents of black rot of grapes, and subsequently as cause of ochratoxin A contamination. Nine different black Aspergillus species have been identified on grapes with different secondary metabolites profiles. However, the main source of OTA contamination in grapes is A. carbonarius, followed by A. niger and A. welwitschiae. This contamination is strongly related to climatic conditions, geographical regions (i.e South Mediterranean climate is highly conducive), grape varieties, damage by insects, growing season (high susceptibility from early veraison to harvest, with a peak at ripening), and great variations may occur from one year to another. In this respect, the right management of the grapes implies several strategies, such as implementations of good agricultural practices, predictive models and risk maps, in association with the use of insecticides and fungicides when favourable climatic conditions occur. In addition, corrective actions can be adopted in wineries. Recently, studies with strains of A. carbonarius, grown under climate change conditions, showed that while growth was relatively unaffected toxin production was stimulated for some strains, especially under CO2 pressure. However, intra-strain differences could give extremely variable results, especially when considering mixed fungal population differently acclimatized. Then, additional studies are necessary on strains acclimatization, in order to obtain more reliable data on OTA risk under CC scenario.