How Wine is Made 

Vintners vary in their approaches to making wine, but all wine is made from the fermented juice of grapes or other fruit. When yeast converts sugar in fruit to carbon dioxide and alcohol, the CO2 escapes into the air and what's left is wine.

Grapes are picked at optimum sugar/acidity levels that are determined in the field by a device called a refractometer that indicates the amount of dissolved solids. 

After picking, the grapes are taken to the winery, de-stemmed and the juice is squeezed out by a press. The juice is then clarified by settling or by centrifuge before being "chaptalised." Chaptalisation increases the strength of wine by adding sugar before fermentation. This process is also known as amelioration. The process has been especially valuable in northern latitudes and in areas where the natural sugar content of grapes is low. 

Yeast is then added and the wine left to ferment in tanks. It is important that the carbon dioxide is allowed to escape, otherwise the liquid will explode. Red wine is given extended contact with the grape skins so that their color may be incorporated in the wine. 

When fermentation is finished (or is stopped), the wine can be "racked off," or siphoned from one container to another, leaving the sediment, or "lees," behind (sometimes the wine is left on the lees for a period to soften). It then rests in a clean tank to stabilize. Next, it is filtered and bottled and left to mature until the wine-maker deems it ready for drinking.

For more information on Michigan wine, visit the Michigan Wine and Grape Industry Council.

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