Risks related to the presence of fungal species and mycotoxins in grapes, wines and other derived products in the Mediterranean area.

The Mediterranean Basin represents the most important grape-producing area in the world with the highest wine production and a moderate consumption of fresh table grape and dried vine fruits. Because of favorable climatic conditions, fungal pathogens and insects can often infect/infest berries; however, fungal saprophytes can also attack grapes and grape-derived products, resulting in mycotoxin contamination, especially OTA. Black aspergilli are responsible for grape bunch rot and OTA contamination from veraison to harvest. Aspergillus carbonarius and Aspergillus niger “aggregate” are the most important OTA producers in the grape chain. The OTA molecule, a phenylalanine-dihydroisocoumarin derivative, is very stable to both temperature and hydrolysis. It is considered a dangerous carcinogenic compound and its toxicological profile includes teratogenesis, nephrotoxicity, and immunotoxicity. Wine is the second source of OTA after cereals in the human diet, and the European Food Safety Authority has set the OTA limit in wines at 2 mg kg 1 in order to protect consumers. Generally, wines from northern Mediterranean countries have lower OTA levels compared to wines from southern ones. Depending on wine-making techniques, OTA levels show a descending gradient from red to rose´ and dry white wines. In sweet or special wines, the OTA content depends on the dehydration process, decreasing from grapes dried in the sunlight, in cool-dry and in hot-dry chambers. OTA contamination is usually higher in dried vine fruits than in wines. Prevention during pre- and/or post-harvest phases is the best strategy for reducing fungal colonization and mycotoxin contamination of grapes. In the vineyard, the use of good agronomical practices and fungicides is recommended. Minimize the interval between harvest and storage or vinification. During the wine-making process, the use of malolactic fermentation (red wines) and fining agents and the increase of wood/bottle aging time can significantly reduce OTA levels in wines.