Wine is fermented grape juice. All wine begins in the vineyard, with the grapes. The grapes are picked at the point where they are ripe enough to have the right amount of sugar, balanced with the right degree of acidity (pH) and flavors.

At the core of wine making, be it professionally or at home, is the process of alcoholic fermentation, in which the sugars are converted into alcohol. However, much more happens than this simple chemical process. The grape skins contain color and flavors which come into contact with the juice once the skins are broken.

Most white wines and rosés (made from black grapes) are crushed before fermentation begins, so contact with the skins is limited. In making red wines the skins ferment along with the grapes. Often they are allowed to soak in the juice after fermentation to give the wine as much flavor and color as possible. Only then is the entire mass pressed and the skins removed.

Red wine is often aged in wooden barrels after fermentation; white wines are usually aged in steel tanks. Both types sometimes undergo a second fermentation, during which the harsher (malic) acids are converted to softer (lactic) acids. This is almost always done with red wines, and in white wines sometimes only partially or not at all.

Sparkling wines such as champagne (in which both black and white grapes are used) begin like normal white wines. The wine is fed a ‘dosage’ of extra sugar and yeast and undergoes a second fermentation. This results in more alcohol and also carbon dioxide gas, which is trapped in the bottle and gives Champagne its characteristic effervescence.

You would read in good Wine 101 guides that in fortified wines such as port, the alcoholic fermentation is interrupted by adding brandy, which kills the yeast. Since many of the sugars have not yet fermented, the result is a sweet wine.

Wine-making terminology:

Destemming
All stems are removed from the grapes using the ‘destemmer’.

Skin Contact
The process during which the juice of grapes rests in contact with the grape skins; in red wine, the process by which the wines absorb color, tannin, and other substances.  This is not normally used in white wine production, but occasionally used to enhance the aromatic character of the wine.

Pressing
The juice extracted under pressure after ‘pressing’ for white wines and after fermentation for reds, usually with more flavor. Used as a blend with other wines.

Cold Settling
White wine “must” is cold-settled and racked fresh from the press. This removes any grape skin particles that might have travelled with the juice from the press. The result is a clean grape must which is ready for fermentation.
Once the grapes have been ‘pressed, the resulting juice is cooled, sulphur dioxide is added and pumped to a holding tank for "cold settling" so temperature remains too low for fermentation to start so that grape solids can settle out and the fermentation proceed on "clean" juice.

Fermentation
The process of turning grape sugars to alcohol by yeast.

Racking
The process of transferring young wine from one barrel to another barrel whilst leaving the leftover sediment behind.

Fining
A method used for removing particles, or clarifying wine. A substance is added to the wine e.g. egg whites or gelatine in order to capture solids before the filtration process occurs.

Cold Stabilization
A technique of chilling wines before bottling to cause the precipitation of harmless tartrate crystals.

Filtering
The wine is filtered in order to remove impurities before bottling.

Bottling
Filling the bottles, corking, capsuling, labelling and palletizing are the last steps to finishing the wine. Red wines often mature for years before being sold. White wines tend to come to market earlier. Wine is made up of over a thousand different minerals, vitamins and other components and once in the bottle, the wine continues to mature and improve.