We are in the Hill Family Estate Yountville tasting room, eagerly awaiting our next taste of Atlas Peak Cabernet Sauvignon, and we take a gander at the tasting menu. “Rich + blackberry + toffee” Wait! Wine is made from grapes! Where do the aromas of blackberry and toffee come from?!? Do those flavors get added at the winery? Are blackberries soaked in the wine?

These are not uncommon questions and they deserve an answer. If we go out in the vineyard and taste a wine grape, we will probably not find notes of blackberry and toffee. In fact, we will probably not taste anything that is even close to the taste of finished wine. So…how do those aromas get thereafter leaving the Yountville vineyards?

First, let us be clear that we do not add any flavorings to the wine.

When you get the fragrance of cherries in our Cabernet Franc, you can be sure that those aromas came about entirely from the fruit or the winemaking process.

Some grapes do have fragrances that persist throughout the winemaking process. We, unsurprisingly, call those aromatic grapes. Our musque clone sauvignon blanc is an example of the grape that carries aromas from the fruit to the grapes. We call these the Primary Aromas.

The Secondary Aromas are those which are the result of winemaking.

During the winemaking process a number of transformations take place. The most notable is the transformation of hexose sugars (glucose and fructose) into ethanol and carbon dioxide. Often, these sugars will have compounds bound to them that are not fragrant when they are in that bound form. When that sugar is converted to ethanol, these compounds, now free of their bonds to sugar, become fragrant.

Other aromatic compounds are synthesized by the yeast as secondary metabolites. Part of the art of the winemaker is selecting the strain of yeast that is known to produce the aromas that are appropriate to the style of wine being made.

After primary fermentation almost all reds and a few whites are put through malolactic fermentation. To initiate malolactic we inoculate the wine with Oenococcus oeni. This is a bacteria that converts malic acid, which is naturally produced by the grapes, into lactic acid. This softer acid will contribute different flavors and mouthfeel in the wines. Much like the way yeast will cause other transformations besides the well-known change of sugar to ethanol and carbon dioxide, malolactic fermentation will also cause other transformations, for instance, the conversion of citric acid (also found naturally in grapes) into diacetyl, a compound that contributes buttery and sometimes nutty notes to wines.

The last major contributor to the aromas of a newly released wine is the oak (or sometimes acacia wood) barrel used for aging. Depending on the origin of the wood (France, Missouri, Hungary or Italy), the aging of the wood, the degree of toasting the wood underwent in cooperage, and the part of the tree that the wood was taken from, different notes will be contributed to the wine, ranging from almond to vanilla.

Once the wine has been cellared in bottle for a number of years (usually around eight) new scents emerge from the wine that are known as the Tertiary Aromas. These can include earthy and savory notes: black olive, mushroom, forest floor, leather, dried fruit, and tobacco leaf. Tertiary aromas are formed by compounds in the finished wines that, through time, combine with and separate from one another, revealing subtle and interesting complexities in the aged wine.

Tertiary aromas are often the most polarizing and are subject to individual tastes. Some wine lovers wax poetically over old wines that display a lot of tertiaries while others will consider those same wines as past their prime. At the Hill Family Estate Yountville tasting room we often advise those visitors considering cellaring a wine for a long time to try an old wine first to see if those tertiary notes are going to excite or disappoint.