If you grab a bunch of grapes and allow them to ripen under warm conditions, they will most certainly ferment. The skins will burst and natural yeast will enter the fruit, breaking down the sugar and initiating the fermentation process. But as anyone who has attempted wine making will tell you, the process requires a bit more diligence to create a full-bodied wine, rather than a sharp bottle of vinegar. Oz Clarke, in his guide to wines called The Essential Wine Book, considers grape types, vineyard soils, weather conditions and the own wine grower’s creativity top influences in wine quality. But simply put, grapes move through four steps on their way to becoming an oaky red or a crisp white wine. The four steps of preparation, fermentation, maturation, and bottling differ only slightly depending on if the wine to be produced is a red, fortified (port and sherry), or white wine.

Grape preparation for red wine includes mashing the grapes, sometimes with the stems, in a machine. The sugar, water, and acidity from the grapes mix with the tannin from the skins and stalks to form grape juice, or must, which is transferred to giant vats. Fortified wines use a similar method, but some are still crushed by foot or with large stones. Grape preparation for white wines is a more involved process. The extended contact between the juice and the skins after crushing gives red wines their color. To maintain white wine’s clarity the contact between the skins and the juice is dramatically reduced.

The grapes are prepared in one of three ways. The grapes are crushed into a pulp that is then moved through a press. Any remaining solid matter is separated through gravity or centrifugal force. The final juice is then transferred to the fermentation tanks or oak barrels. A second method involves allowing the juice of crushed grapes to naturally drain producing a lighter white wine. Finally, the grapes can be crushed and pressed, then immediately separated from the skins for the clearest tasting whites.

After preparation comes the fermentation process which is a two step process – alcoholic fermentation and malolactic fermentation. During alcoholic fermentation the first flavors of the wine are produced.

Reds are fermented in large steel or wood containers. Yeast will naturally begin to form in warmer climates although sometimes cultivated yeast is added. In cool climates the juice must be heated to kick off that fermentation process.

Lighter reds spend only two to three days in the first fermentation step. Classic, full-bodied reds will ferment for a good two weeks or more. The added stems will provide tannin, which makes for drier reds. Fortified wines are half-fermented in a similar manner at which time brandy is added to the juice, stopping the yeast fermenting processes and preserving the sweetness of the wine. White wines are almost always fermented with special cultured yeast for a minimum of a month. Wine makers have the choice of stainless steel or wooden vats and high or low fermentation temperatures. The combination will produce fine Chardonnay (oak and high temperatures) or lighter dry wines (stainless steel and cool temperatures). It is during this first fermentation period that the grape juice must be turned frequently to prevent wild yeast from pickling the liquid, creating a vinegar-like taste. The second fermentation stage – malolactic fermentation – reduces the acidity of the wine. Bacteria turn the malic acid to lactic acid and is used to various degrees for reds, fortifieds and whites.

The third step in wine making is maturation.

Maturation allows the wines to mellow out before being bottled. Red wines have especially high tannin contents, making the wine undrinkable. If the wine is allowed to settle, however, the bitterness decreases. The character of the wine is fully influenced during this period. The container used in maturation, the length of the process and the temperature all affect the flavor of the wine.

For reds such as Beaujolais Nouveau the maturation process is short and bottling occurs almost immediately after fermentation.

Many reds develop strong characters from long maturation times in newly constructed wooden barrels that impart their flavors into the juice. Reds are known to mature for up to three or four years. All fortified wines are aged in large barrels from anywhere from two to ten years. Whites spend the least amount of time in this maturation process.

With less tannin influence, white wines are not required to mellow as much and can be quickly bottled.

The storage that does take place is done in tanks or barrels. Small barrel storage is particularly beneficial to top quality Chardonnay. During this mellowing process, any leftover sediment in the juice settles to the bottom of the barrels or tanks. Clarification is the final step in maturation and required before bottling takes place.

The final step in wine making is the bottling process. Determining the perfect moment when a wine is ready for bottling requires much skill. The more a wine is allowed to mature, the more character it can develop (such as reds). But too much maturation can ruin the fruity flavor so valued in whites.

All major vineyards employ an automatic bottling line to bottle their wines. Before entering the bottle, though, the wine must be pasteurized. Hot pasteurization was the most commonly used to sterilize for many years, but the heat increased the chances that the carefully developed wine flavor would be destroyed. Cold pasteurization has become more popular in recent years. Sterile wine bottles are filled with nitrogen. When the wine is introduced to the bottle, a nitrogen cushion is created between the wine and the cork, reducing chances of decay. Once the wine has been bottled, the aging process continues developing into what wine connoisseurs call the bouquet.

In essence, wine is little more than the alcoholic juice of fermented grapes. But truly excellent wines are not left to nature’s whim. The four steps of preparation, fermentation, maturation and bottling are complexly influenced by outside factors such as temperature and grape selection. Fine wineries produce such excellent wine because they have researched and developed special grape strains, perfected their fermentation and maturation processes, and preserved their creations in sterile bottles.

The wines of each vineyard also have distinct characters, however, attesting to the fact that although wine making requires the precision of a science, it benefits enormously from man’s own creativity.