Why do Wines Have a Peppery Smell/Taste?

                   Syrah is one of the most well known grapes for its peppery characteristics

If you’re a Syrah lover (especially those produced in warm climates such as the Rhone Valley), then you’re most likely more than aware of this varietal’s pepper nuances.   There’s a scientific reason for this pepper and it has do with a chemical called rotundone.  This same substance, rotundone, not only appears in Syrah grapes but occurs in both white and black peppercorns.  Unlike many parts of a grape that are changed during the fermentation process, rotundone survives fermentation and ends up in your glass creating a spicy, peppery character.

Rotundone is a relatively newly discovered compound.   It was identified only fifteen years ago by researchers who were on a quest to investigate the science behind the peppery smell in wine.  The chemical, present in the skins of grapes, is found in miniscule amounts.  But, rotundone is such a  powerful aromatic compound that one teaspoon can cause an Olympic size pool to smell like the inside of a pepper grinder.

Both the white pepper smells of cool weather Syrahs, as well as the black pepper of Syrah grown in warmer terroirs are due to rotundone.   And, it’s not only limited to Sryah grapes.  In fact many varietals including Cabernet Sauvignon, Grenache, Pinot Noir and even the white varietal Gruner Veltliner have been discovered to have rotundone.  Interestingly, the rotundone chemical is also present in marjoram and even some cocoa powders, and the smell is also present in well-aged leather.