The Anatomy of a Grape

The Anatomy of a Grape

Knowing and understanding grapes is absolutely essential to making good wine. After all these little berries are what it all starts with right? By their very nature grapes are the perfect winemaking fruit. No other fruit contains the perfect amounts of sugar, acidity, and phenolic compounds to create such an amazing beverage. Any other fruit requires additional sugar or other ingredients to even produce alcohol. Let’s get to know our little friend a little bit better. Shall we? Physical Components of the Grape The Skin At only six to ten cells thick you wouldn’t think there’s much to the skin of a grape. However, this membrane contains many key elements for red wines. Less so for white wines as the juice spends little time in contact with the skins. The outer surface of the skin is the cuticle, a wax like covering that waterproofs the berry. Protecting it from outside influences.¬†Within the thin skin are a ton of components including aromatic substances, potassium, and phenolic compounds. Phenolic compounds refer to a group of compounds, however, there are two very important ones that need to be explored. The first are anthocyanins. These are pigment compounds that give the grape its color and in turn gives red wine its color. As wine ages these anthocyanins combine with other phenolic compounds which serves to stabilize the color of the wine. The second phenolic compound of interest are tannins. Also present in the seeds tannins give wine an astringent and bitter taste. Tannins also combine over time and alter the taste and mouth feel of a wine. Red wines in particular get most of their flavor and spunk from the skins. Merely pressing red grapes and fermenting the juice results in what the French call “Blanc de Noir” meaning white wine from red grapes, or literally white from black. The Pulp The bulk of the grape is made up of the pulp beneath the skin. This is where the grape juice comes from.¬†Vacuoles contain the juice and when broken release the “free run” juice. As you can see in the diagram the pulp contains many compounds of its own including: sugar water aromas potassium tartaric acid malic acid In white wine making the pulp provides the bulk of the flavor and acidity. Red wines get their flavor first from the skins but also from the pulp. Seeds Moving inward we come to the seeds. These are large caches of tannins. So much so that as winemakers we must be careful not to crush the seeds during the pressing of the grapes. By crushing the seeds, and stray stems, the tannins are overdone. If this happens your wine will need much more time in the bottle to become palatable. Chemicals Within The Grape The chemical makeup of a grape is quite diverse and complex. We’ll just hit the major components here. Sugars The sugars within the grape are what the yeast consume to produce the alcohol in wine, as you already know. What we refer to as “sugar” in a grape is actually a combination of several different kinds of sugar. Primarily there is...

Read More