Monitoring of ochratoxin A fate during alcoholic fermentation of wine-must

Ochratoxin A (OTA), a mycotoxin classified as a possible human carcinogenic (IARC) is commonly present in cereals, grapes, coffee, species, cocoa and, due to its thermostability, in their derivatives. Its extraction from naturally contaminated grape occurs during the initial phase of wine processing, taking place by solid–liquid (berry-juice) contact. In this paper, the effect of alcoholic fermentation on OTA concentration in must fortified with toxin was studied in presence or not of grape skins and using, as inoculum, two different commercial yeast strains. The OTA concentration was determined both by HPLC-fluorescence detection (HPLC-FL) and RIDASCREEN® Ochratoxin A kit, after immunoaffinity column clean-up. The two methods resulted reliable in the toxin concentration range tested (0.5–15 μg kg−1) in red and white wine-musts analyzed. The study proves the detoxifying effect of alcoholic fermentation on OTA level, even if toxin depletion trend, starting within the first two days, is quite constant despite kinetic variability of metabolic phenomena during fermentation process. OTA adsorption effect of grape skins (5–12%), appeared at beginning or ending of fastest ethanol production phase, seems to be related to skin tissue nature. Both yeast strains tested, Zymaflor VL3 (Laffort) and VIN7 (Anchor-Lallemand), were able to reduce OTA level (from 57 to 79% of initial amount) during the alcoholic fermentation of red and white wine-must. The greatest detoxifying effect was observed for VIN7 strain.