Wine Making - A Simple Explanation of a Complex Craft

It begins in the vineyard

Despite common misconception, wine making doesn't actually begin in the winery.

The quality of a wine is not simply under the control of the oenologist. Well before the grapes are even stomped on, quality is determined by practices of the viticulturalist to raise healthy, balanced vines with adequate level of ripeness in the wine grapes whilst they mature on the vines.

This means achieving the right levels of sugar and acids, control [or better still, elimination] of pests and diseases, and overall high quality wine grapes that are not bloated with water, but have optimum varietal characters and flavours achievable for the region.

Vintage [harvesting] takes place primarily during the summer months in each hemisphere respectively.

How do they know when to pick the grapes?

Exactly when grapes are picked depends ultimately on the style of wine being made. [ie how much acid/sugar/colour etc is desirable]. The same grape picked at a different time has a bearing on what can be made with it.

Take Chardonnay, as an example. This wine grape can be used to make a broad range of styles from a light-bodied sparkling wine to a complex full-bodied dry style.

Wine grapes are tested by random sampling from vines at varying locations in the vineyard to represent the total harvest. The old days of a winemaker tasting the grapes to make the call on harvest timing have been replaced by modern, more analytical testing methods which take place in a laboratory ... although the former method still happens around the world.

Simulating the effect of the winery crusher, sample berries picked from different areas withing the vineyard are pressed to extract juice. The juice is tested for total soluble solids. Vitis Vinifera [the species of vines used for wine grapes] vines produce grapes that are higher in soluble solids, but lower in acids than table grapes.

As grapes ripen, they generally increase in colour and sugar, but decrease in pH and acidity. That's why timing of vintage is crucial if you want great wines.

Testing identifies many aspects and elements, but let's just have a quick look at the major ones:

Sugar

Measured usually in degrees Brix or Baumé. This represents the resulting alcohol concentration in the wine - eg a measure of 12.5 degrees Baumé will produce wine at 12.5% alcohol by volume max.

Titratable Acidity

This is an indicator of overall acidity of the grape juice, and is expressed as either grams tartaric or sulfuric acid per litre, depending on where in the world the winery is.

pH

If the pH is too high at time of harvest, you'll have trouble maintaining stable colour in the juice.

The basic steps of winemaking

In very simple terms, the basic winemaking process is the same regardless of what colour grapes are being used.

Step One: Extract the grape juice

Step Two: Ferment the sugar

Step Three: (optional) Store the wine in casks or tanks

Step Four: Bottle the wine

That's it! Sounds simple enough - but in reality, every different type or style of wine requires immaculate handling and monitoring during all phases of the process.

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