The Wine Pages: Homebrew winemaking
Making wine from grapes. Us home winemaking addicts can turn almost any organic produce into wine, but sometimes we forget the humble grape. Most of the wine in the world is made from grapes: And for a good reason. Grapes have winemaking qualities that are superior to any other fruit. Only the juice of the wine grape contains roughly the correct balance of sugar, acid, tannin and nutrients to make a well balanced wine. All the other fruits we use, e.g. apples or blackberries need to be handled differently to produce a wine with the correct balance. A wine made entirely from apple juice, or elderberry juice would be too strongly flavoured and too acid. Pure apple juice does not contain enough sugar for a 10% plus strength wine. Only grape juice has the sugar and acid content to make a well balanced wine.
Making grape wine is quite simple. You don't really need a recipe as such, just a grasp of the process. Most grapes, even red grapes, have white juice. The grapes must be crushed and pressed to extract the juice. About 15lb of grapes will produce around 1 gallon of juice. Ideally this grape juice will contain exactly the right balance of sugar and acid for winemaking. However, in colder climates, such as the UK, grapes are apt to be low in sugar and higher in acid.
Thus it is important to measure the gravity of the grape juice and adjust up to around 1080 gravity with some additional sugar. If the juice is low in sugar, then it is apt to be high in acidity, so you might need to water the juice down a bit.
Grape juice oxidises extremely easily. As soon as the grapes are pressed you must add at least 1 campden tablet to get some sulfite into the must. I normally then leave the grape juice for 24 hours to allow the solid particles to settle out on the bottom of the container, and then rack the juice off the gunk before adding the yeast.
Just about any yeast can be used, but again, climate can dictate certain choices. In the UK grapes are often not ripe until October. At this time the ambient temperatures can be quite low - it is not impossible to get frosts in October. If you are fermenting in an unheated location, and it is late in the season, it is often wise to use one of the yeasts designed for lower temperature fermentation, such as Gervin B.
Then it is a case of proceeding normally, but paying particular attention to the acid balance and the amount of sulfite. Additional sulfite should be added after fermentation to avoid oxidation, especially in red wines.
Grape wine is not a simple wine to make - it requires a lot of grapes and a lot of effort in pressing and crushing. Therefore you are doing yourself an injustice if you run off and drink the stuff the moment it has finished fermenting. Providing the wine is well sulfited, I recommend a minimum of 1 year maturing before you start drinking.
As a general rule with most season wines, do not start drinking last years batch until you've started making this year's batch!