The shikimic acid: an important metabolite for the Aglianico del Vulture wines

Shikimic acid is a precursor for the biosynthesis of aromatic amino acids and flavonoids (anthocyanins, tannins and flavonols). In the pharmaceutical industry, it is obtained by extraction of star anise from China, and at a yield of 3-7% it is used for the production of antiviral drug, e.g. oseltamivir. Unlike flavonoids which are only present in the grape skins, shikimic acid is present in the juice together with hydroxycinnamil tartaric acids (caffeic, ferulic and p-coumaric acid). Therefore, their content in white wines may not be negligible and their presence may explain the epidemiological studies that showed a reduced incidence of cardiovascular diseases also in people with moderate white wine consumption. The content of shikimic acid has been used to characterize wines. In southern Italy it has been used to distinguish Aglianico grape, which holds medium-high content, from Negroamaro, Primitivo and Uva di Troia grapes who have rather lower levels. It could be useful also to distinguish Fiano di Avellino (high value) from Fiano Minutolo (low value). However, results of a recent work showed that the shikimic acid content decreases significantly during the ripening of the grapes and therefore its content in wine is strongly influenced by the harvest period. Finally, in a recent paper it was highlighted the increase in shikimic acid content at the end of fermentation in an Aglianico del Vulture wine, produced in the area of Rapolla (PZ, Italy) municipality during the 2013 harvest. These last experimental results explain why the values of shikimic acid were lower in grapes and surprisingly higher in wines produced in the 2011 and 2012 harvest.