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 why it is referred to as the noble rot, it can help make superb wines.

Grape sellers normally tell wine makers if they believe a particular lot of grapes has been infected by botrytis as this will affect your wine making process.

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Photo by: Agne27