Growing the Grapes for Wine
Grapes to make wines grow on vines. There are many different types of grapes, but the one considered the best wine grape is the Vitis vinifera. It is considered optimal because it has the right balance of sugar and acid to create a good fermented wine without the addition of sugar or water. It has been said that the wine is only as good as the grapes from which it is made. While that is normally true, a poor winemaker can ruin good grapes. On the other hand, a good winemaker isn't going to make great wine from inferior grapes.
Wines made from a single variety of grapes are called varietals. So, a wine made 100% from Cabernet Sauvignon grapes is a varietal wine. The cabernet sauvignon, zinfandel and merlot grape are varieties of grapes.
Vines start producing grapes about three years after planting. They become a useable crop after five years. They reach their prime in terms of crop yield between ages ten and thirty. Vines can grow for a hundred years, though production is reduced as the vine gets older. However, reduced production can actually lead to better grape and therefore wine. Some very good wines come from old vines. That is generally why small boutique vineyards that have been passed down from generation to generation tend to have better wines.
The Harvest and it what means to Wine
Weather is also a major factor is determining whether a year is going to be a good vintage. For example, was there enough heat during the growing season to lead to enough sugar? At harvest time, the short term effects of weather are quite important. To produce great wine, the fruit should be ripe, but not overripe. The grape must also have a high, but not overly high, sugar content. It's a delicate balance and it takes skill and intuition to know the exact time to pick the harvest. Think of raisins. As the fruit dries, the water evaporates and what is left is the sugary fruit. If it should happen to rain at the point the wine grapes are ready, and before the grapes can be harvested, it will cause the water level of the grapes to increase, and the sugar level to drop. This is not good and might render the grapes useless for wine making purposes. Unfortunately some winemakers will still use the grapes to make wine by simply adding sugar during the wine making process. This is also not good and you can usually find those wines on sale in your supermarket. Small batch wine produces that make boutique wines will never add sugar.
Every year the wine grape grower plays a game of chance and must decide the exact time to harvest. If he knew it wasn't going to rain, he would just test the sugar content until it was at the ideal levels, and then harvest. If he harvests the grapes too soon, he will end up getting a wine too low in alcohol content as there will not be enough sugar to convert to alcohol. These wines will be what is called "thin" and their taste will reflect it. If the harvest is delayed, there may be too much sugar in the grapes and that will cause a low acid content. This also affects the taste and the aging possibilities of the wine. The key to a making a wine that is world class lies on the judgment call of the wine grape grower.
How Grapes Become Wine
In some small wineries, grapes are still crushed by stomping on them with your feet in a big vat. Unlike what most envision, it is not done barefooted and it is done with rubber boots on the feet. The rubber boots protect the stompers from the vines and stems that may have fallen into the stomping area. The grape juice then falls into a vat. A more practical way used by most wine makers is to use a machine which does the job and at the same time removes the stems.
Skin and seeds might immediately be removed from the juice or may be left in there, depending on the grape and wine. Separation may not immediately occur, especially for red wines, as the skins and stems are an important source of tannins which affect the wine's taste and maturity through the aging process. The skins also determine the color of the wine.
Maceration is the period of time when the skins and seeds are left with the juice. It may go on for a few hours or a few weeks, depending on the type of wine. After the exact amount of time, the pressing will occur. One way to press the grapes is to use a "bladder press". This is a large cylindrical container that contains bags that are inflated and deflated several times. Each time it gently squeezes the grapes until all the juice has been extracted, leaving behind the rest of the grapes. You can also separate solids from juice through the use of a centrifuge. This machine is a round bowl with walls similar to a strainer. It spins at high speeds and forces the juice out throuhg the walls. Except for the juice, every other part of the grape stays in the bowl.
Grape juice is turned into alcohol through the process of fermentation. Grapes on the vine are covered with yeast, mold and bacteria. By putting grape juice into a container at the right temperature, yeast will turn the sugar in the juice into alcohol and carbon dioxide. The grape juice will have fermented after the alcohol is produced.
Yeast also serves to give flavor to wine. However things on the outside of a grape are not necessarily so good for the production of good wine. An example is acetic bacteria, it is on the grapes and can cause the wine to turn to vinegar. The winemaker commonly eliminates unwanted contaminants by using sulfur dioxide. Unfortunately, the sulfites which remain in the wine may cause discomfort to some wine drinkers if they have allergies to sulfites. Some winemakers use organic wine making methods and do not add sulfites. The grapes are organically grown without the use of pesticides or other chemicals. These organic wines are subject to unpredictability as to the taste and texture, and are affected by the different flavors added by the yeast. Yet if done properly, organic wine is as delicious as others. There is still some controversy over natural yeast on the grape, as a number of wine makers claim that there is no documentation that any yeast lives on the skins of grapes that can lead to alcoholic fermentation. They propose that these spontaneous fermentations occur due to commercial yeast populations that live in the winery and have not been eliminated or otherwise eradicated from the wine making area.
Winemakers have many different yeast strains to choose from and can use different strains at different times during the wine making process. The most common wine yeast is Saccharomyces. As the yeast works, it causes the grape juice to get hot. But if it gets too hot, the yeast will not work. Temperature control is a very important component. One modern way to deal with this is to put the juice into large stainless steel containers that have refrigeration systems built around the sides. The winemakers can precisely regulate the temperature.
The fermentation process usually lasts from five to seven days from beginning to end.
A less modern, but still wide widely used way to ferment wines at small batch wineries is to place it in small oak barrels. Barrel fermentation is usually done at a lower temperature in temperature controlled rooms and takes longer, perhaps around 6 weeks. The longer fermentation and use of wood contributes to the flavor and the cost of the wine. Most boutique wines are made using barrels as it is considered the traditional and time tested way to ferment.
The skins and pulp which remain in a red wine vat will rise and float on top of the juice. This can cause problems as if the grape skins and pulp dry while floating on the top, it becomes a perfect breeding ground for bacteria that can damage the wine. To prevent the formation of bacteria, the winemakers push the skins and pulp back down into the juice. This extremely labor intensive work is usually done at least twice a day. The winemakers must be vigilent and keep a close eye on the production process. In large modern vats, this is accomplished by pumping juice from the bottom of the vat over the top. Some winemakers even use a screen to keep all solids submerged under the juice at all times.
Eventually the fermentation process is complete and the yeast no longer changes the sugar into alcohol. After this process is complete, what you have left is the wine, dead yeast cells and various other residual substances.
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