How Wine Is Made

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wine-makingLeft to its own devices, the juice of any fruit or vegetable will, in time, ferment and turn itself into wine. Loosely speaking, wine is simply a lightly alcoholic, fermented drink, so you can get rhubarb wine, rice wine, carrot wine, plum wine, crab apple wine - any kind of wine you like. More precisely, however, the word wine on its own is universally recognised to mean the fermented juice of the wine-making grape. The particular type of grape used is known botanically as vitis vinifera, and is very different from the usual eating varieties. It makes a uniquely complex, many dimensional, infinitely variable drink, which is in quite a different class from the fermented juice of any other fruit.

There has always been a great deal of song and dance made about wine and its many virtues; wine bores can go on about it for hours. But what, in plain language, makes one wine different from -and perhaps more expensive than - another?

How wine is made

Essentially wine doesn't have to be made, it makes itself, because all the necessary ingredients for wine-making are contained within the grape itself. During the process of fermentation (which is spontaneous, as anyone who has ever left a fruit salad hanging around too long will know), yeast works on the natural sugar present in the fruit and converts it into alcohol, giving off carbon dioxide as a bi-product.

You will see a white bloom on the skin of any grape berry, although it shows up more clearly on black grapes. This is the yeast. Inside the berry, the juice is sweet; there you have the sugar. Hanging on the vine, these two ingredients are kept apart by the water-tight skin, but crush the bunch or even a single berry and the two will begin to react together. If the crushed grapes (or just the juice) is left unchilled, the seemingly magical process will start very quickly and not stop until either all the sugar has been converted into alcohol by the yeast or the alcohol level has become so high as to kill off the active yeasts. Not all sweet wines, as you might conclude from this, are terrifically high in alcohol; many, such as the high-quality German wines, combine sweetness with a low alcohol content. To achieve this, the fermentation is stopped artificially before the yeast has completed its job. To make cheaper sweet white wines, any yeasts remaining after the fermentation has stopped will be filtered off before a slug of sweetness is added back to the wine.

As well as yeast and sugar, there are other natural wine-making ingredients present in grapes, contained in the skin and the stalk. If you bite into a grape, the overall sensation is of sweetness, but concentrate on the skin or chew on the stalk and the taste will be tart, making the insides of your cheeks feel puckered and dry. The cause of this strange taste and sensation is tannin, which acts as a preservative. It plays an important role when wines, particularly reds, are destined to be matured before being drunk. Since tannin is rather bitter, care is taken not to allow the skin and stalks which contain it to remain in contact with the pressed juice when making delicate white wines; the skin, stalks and the pips (which are too bitter for any wine) are all filtered off before fermentation. This is not the case with red wines, where a certain amount of tannin is to be encouraged.

Red wines generally have more substance and more 'body' than white wines, and are almost all pretty dry, so the tannin taste is not at odds with the intrinsic flavour. As red wines age, the harsh characteristics of the tannin soften and mellow as well as contributing an important dimension of their own to the wine. If you taste a red wine intended to be aged when it is too young, the tannin is easy to detect, giving the wine a hard, easily identifiable, mouth-puckering edge.

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