Evolution of ochratoxin A content from must to wine in Port wine microvinification

摘要

To study the evolution of ochratoxin A (OTA)content from must to wine during the making of PortWine, grapes from the five most common varieties ofPort Wine were harvested and combined in equal percentagesin order to perform microvinifications. Threesets of assays were studied: a blank (A), where the mostcommon Port Wine-making process was used; in thesecond (B), a solution of OTA was added to the initialmust; in the third (C), the grapes were aspersed with aninoculating solution of OTA-producing fungi. Sampleswere collected, in duplicate, on four different occasionsthroughout the process. The influence of the addition ofSO_2 to the must was also assessed in each set. Thequantification of OTA was based on the standard referencemethod for wines (European Standard prEN14133), which includes clean-up via immunoaffinitycolumns and HPLC with fluorescence detection. Thelimits of detection were 0.076 μg/l for wine and0.114 μg/l for must. The method was validated byassessing the precision, accuracy and by obtaining anestimate of the global uncertainty. Overall, the levels ofOTA observed during the vinifications dropped by up to92%, and no grapes used in this work were contaminatednaturally.