Читать книгу Wine Faults and Flaws - Keith Grainger - Страница 71

Secondary aromas are the ‘vinous’ aromas resulting from the fermentation – put simply, the smells that are different in wine to those of unfermented grape juice. Many compounds in grapes are precursors of secondary aromas, including free amino acids, phospholipids, glycolipids, aldehydes, and phenols. During the fermentation process, numerous chemical changes and enzyme‐catalysed modifications take place producing secondary aromas. Numerous esters are generated in the process, and the aromas of these are often assertive on the nose of young wines, sometimes imparting pear, banana or even boiled sweet or bubble gum characteristics. Several fatty acids are also generated during fermentation, and some of these, if produced at high concentrations, can be distinctly unpleasant and render the wine flawed or even faulty. These include acetic, isobutyric, isovaleric, butyric, hexanoic, and decanoic acids. Several volatile sulfur compounds may also be produced from their precursors. Some of these are desirable contributors to a wine's aromatics, but others, if they remain in the wine, may also contribute to faults. Also in the secondary aroma group are the by‐products of MLF, and bâtonnage (if undertaken), which may contribute to aromas of butter and cream. Compounds extracted from oak, giving aromas of vanilla, coconut, or toast may also be considered secondary aromas.