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...

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Crushing and Destemming Grapes

Crushing and Destemming Grapes

As you well know, grape juice comes from grapes. Extracting that juice is therefore the very first step in making wine from fresh grapes. Not to be confused with pressing grapes the crushing of grapes merely breaks open with skin allowing the “free run” juice to pour fourth.  Pressing on the other hand is where you flatten the things to get out as much juice (or wine in the case of reds) as you can. Crushing and Destemming Machines Modern crushing and destemming machines consist of a large steel or aluminum trough with a screw in the bottom. As the screw turns the grapes are gently squeezed and pulled from the stems at the same time. Out one end pops the stem and out the other is your elixir of life (to be). The crusher / destemmer shown here has a rubber edge on the screw so that the grapes are crushed as gently as possible. If you crush grapes too hard you’ll end up crushing the seeds. This imparts more tannins and astringency in your finished wine. It also can impart a stemmy or “green plant” taste. Crushers can be purchased or rented without the destemmer. This is a bad idea in most circumstances. Unless you’ve hand picked the grapes and they are already stem free you’re going to want the destemmer.  Otherwise you’ll be spending hours picking stems out of your must! There are a few different kinds of crushers that are made for specific fruits. Apples and pears must be crushed in a different crusher. Keep this in mind if you ever want to venture out into making fruit wines. Why is Destemming Critical? Tannins my friend. Grape stems and seeds contain high concentrations of tannins. Leaving them in the must during fermentation will result in a wine so tannic you likely won’t enjoy drinking it. Grape skins also contain tannins so don’t feel like your eliminating all tannins by excluding the stems. The grape skins will provide plenty of tannins without all the funky flavors. Things to Watch For While Destemming The destemming process is a perfect time to look over all the grapes you’ve purchased and are processing as you load them into your machine. Make sure that nothing funky is getting into your wine such as bugs, sticks, or bad grapes. Look over your grapes for evidence of mold, dehydrated grapes, and botrytis. Moldy grapes just don’t make good wine. You’ll taste that mold forever more in that wine. Dehydrated grapes will make for a sweet and raisony wine. Which isn’t a bad thing…if that’s what you want in your wine. Botrytis, also known as the noble rot, is a fungus that infects ripe grapes. The presence of botrytis is not always a bad thing. It can make your wines quite sweet and delightful if that’s what you want. The fungus attaches itself to the grapes, penetrates the skins and basically drinks the water in the grape. In so doing the flavors within the grape are concentrated and the sugar content relative to the amount of juice is increased as the water is removed. This is...

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