How Wine is Made

Making wine is a lot like making love. Both processes are simple and natural, yet the quality of execution can create results ranging from the sublime to the abysmal.

Wine will transform from grapes with minimal help. The berries are covered with natural yeasts when they mature, and if you take a few bunches, crush them in your hands and throw them into a pot, the yeast will start to transform the sugar into equal parts of alcohol and carbon dioxide within a day or two. After a week or so, the process will be complete and you'll have a simple wine.

The earliest winemakers did just that, except in larger volume; basketfuls of grapes were thrown into large barrels or other such tanks, and people actually did stomp the grapes with their feet, a method still used in some areas of Europe. The resulting mess of juice, skin and pulp was left to ferment, a process that speeds up the hotter the temperature. Over the course of a week, the concoction burped and bubbled along, almost as if it were being boiled. When the activity stopped, the juice would be drained away and put into storage vessels of some sort, whether leather sacks or earthenware vases.

As the centuries passed, each step of the operation became a bit more involved. For instance, the leftover grape skins were pressed to remove more juice, often particularly rich and flavorful because more of the essence of the skin was recovered, providing more color to red wine. That used to be done by loading the pulp and skins into cloth sacks, and piling stones atop them to squeeze out the juice; mechanical presses didn't become common until the 19th century. The juice was then added to the "free-run" stock.

Eventually, winemakers took to leaving this initial young wine in large tanks for a while, allowing the sediment to settle out before storing the wine in smaller vessels. At some point, it was noticed that the wine improved with age, especially if it was kept in oak barrels.

Winemaking reached its pre-industrial peak toward the end of the 1900s, by which time the basic practices were fairly universal. Just as now, state of the art techniques could be found in Northern California, especially in the Sonoma and Napa Valleys. There, wineries were built so the rear walls abutted hillsides. The front facade might stand three stories high, yet a road behind, between the hill and the winery, would bring wagons level with the back top floor.

Depending on the preferences of the winemaker, he would either start with young wine that farmers had crushed, pressed and fermented on themselves, or he would buy grapes and perform that initial process on his own premises.

In either case, the immature wine was put into large holding tanks on the top floor, often with 500- and 1000-gallon capacities. After a year, most sediments settled out, and wine was siphoned out of the top of these tanks so as to leave the silty remains behind. Gravity took the wine downstairs to smaller barrels on the next floor, where real aging began.

Tending the wine consisted of topping off each barrel every week; as minute amounts evaporated through the wood, a little more wine was added, to insure that wine came into as little direct contact with air as possible. After finishing out the winemaking year on the second floor, the wine was siphoned to the bottom floor, where it would pass another year of aging and being topped off. Then it was sold either by the barrel or bottled and sold.

The difference between bad wines and good had to do with a number of factors. Grape quality was one, and so was the cleanliness of the equipment; mildew or other contaminants can ruin wine. Weather that turns too cold or hot could stop the fermentation process or move it along too quickly, which will show in the final product. Failure to keep barrels topped off can lead to oxidation, which results in damaged wine and inferior flavors. In the old days, creating a superior vintage often had a lot to do with avoiding mistakes and the vagaries of weather. On the positive side, wise blending of different grape types or grapes from different vineyards were components of the winemakers magic. Now, many of these factors are scientifically understood and controlled; it's a lot easier to avoid making a bad wine. But the quest for a superior wine is still more rigorous than ever.

Making Red Wine

Hearty reds are perhaps the least complicated wines to make and the most forgiving of small mistakes since the strong nature of the flavor stands up so well. Depending on the winemaker's desires, the grapes are usually picked when they reach between 24 and 26 percent sugar content. Unlike in the old days, when the vineyard owners often crushed the grapes and delivered young wine to the winery, modern winemakers want as much control as possible over the process and do their own grape crushing.

The typical machine crusher uses centrifugal force, and as the grapes are thrown into it, the bunches are tumbled around with enough velocity that the berries are automatically crushed and removed from the stems. The juice and pulp fall into a sump and are pumped into a tank while the stems are ejected at the other end of the crusher.

Most modern wineries use stainless steel fermentation tanks--they're easier to clean than wood or most other vessels, and any off tastes can make their way into the wine. It takes about five or six tons of grapes to create a thousand gallons of juice, and tanks of that size or larger are standard. Once they're full, sulphur dioxide is typically added to kill natural yeasts, and a scientifically developed yeast will be mixed in in carefully measure amounts to insure that fermentation will proceed in a more predictable manner. Fermentation takes place within the range of 54 to 98 degrees, and the winemaker will do everything possible to keep the juice well away from those extreme ranges so fermentation doesn't stop or so heat doesn't damage the flavor. And while summer daytime temperatures in Northern California don't often reach those upper ranges during the fall harvest, the fermentation process creates heat that can push the pulpy juice to dangerously high levels if the outside temperature is too warm. Cool warehouses or double-sided tanks are common, the latter designed so cold water can circulate and reduce the temperature. The winemaker is trying to strike a balance--cooler fermentation leads to fruitier, more subtle flavors, hotter fermentation creates more intense flavors and colors.

Fermentation will go on for a week or so, and every few hours during this time the juice at the bottom of the tank is pumped over the grape skins floating on the surface in order to extract more color and flavor. Meanwhile, the sugar converts to roughly equal parts of carbon dioxide and alcohol, explaining why initial sugar content is so important to the wine maker. The ideal alcohol level for a red is usually 12 or 13 percent, amounts derived from initial grape sugar contents of 24 to 26 percent.

When fermentation is complete, the juice is pumped into large oaken tanks--perhaps 500 or thousand gallon containers--where aging begins with the young wine's contact with the wood. After the fermentation tanks are emptied, the skins and other grape by-products are put into a press, and the last of the juice is extracted; this is added to the rest of the wine.

Practices vary from winery to winery, but the standard procedure is to leave the wine in large tanks for a year. During this time, the vats are topped off as the wine evaporates so that air can't damage it, and the individual lots are sampled to check for any spoilage. The wine may be transferred from one tank to another as part of the blending process, or to clean vats or change the size of the vessel--the smaller the tank, the more the wine comes into contact with the oak, and the faster the aging process.

After a year of this treatment, most fine wine is put into 50-gallon barrels, where the real mellowing of the wine takes place, with heavy exposure to oak. French barrels are often considered best, but American oak is increasingly used as well. In either case, the unique flavors of the different types of oak barrel will be imparted to the wine; at the same time, the wine softens, losing its previous harshness.

Topping off and pumping around between barrels continues, at least for one year, and often two. During this time, different kinds of grapes may be blended to create a particular style of wine--for instance, 80 percent Cabernet Sauvignon may be mixed with 10 percent each of Cabernet France and Merlot, to create a "Bordeaux-style" wine. Or, in the California fashion, Cabernet grapes from different vineyards in the Napa Valley may be blended.

Most reds are kept for three years before they're released, and as a new harvest approaches, the wine made from grapes crushed those three years ago will be bottled and put up for sale. The year of the harvest is noted on the bottle; if there is none, it's a non- vintage wine, probably a blend of several years. Though such wines don't have the same prestige as vintage wines, they sometimes compare very well.

Some reds will continue to improve for several years in the bottle, but most will be ready for drinking as soon as you buy them. The winemakers or wine merchants will usually suggest which are most suitable drinking or more aging.

Making White Wine

Just as sediments or other impurities will show in a transparent white wine, the inherently delicate flavor of whites will also highlight the smallest flaws in production, whether from overheated fermentations, tainted barrels or oxidation. Avoiding making a bad white wine is almost as difficult as making a respectable red.

The grapes are typically picked when they reach 22 to 24 percent sugar content, and they're dumped into crushers which remove the stems, just as with red wines. But unlike with the reds, the juice and skins are not fermented together. After the free-run juice is pumped off, the skins are immediately pressed to recover as much extra juice as possible, which is then added to the fermentation tanks. The skins are discarded from the winemaking process at this point.

White wines are fermented almost exclusively in stainless steel tanks, unlike reds which may be fermented in wooden or other vessels; the white is just too vulnerable to damage from off flavors that may resist cleaning from a wood tank. Sulphur dioxide or an equivalent compound is thrown into the tank to kill the natural yeasts, and other yeast is added to start the fermentation process in a controlled manner.

Though red wines can stand a fairly warm fermentation, whites are subject to injury to the ultimate flavors, so chilled tanks and warehouses are quite common in order to slow down the fermentation and keep it under control. While reds ferment in a week to 10 days, whites are sometimes fermented over the course of two or three weeks.

The final wine will have an alcohol content of 11 or 12 percent--roughly half the level of the original sugar content if all the sugar is fermented away, and a percent or so less than the usual red wine. The lower alcohol content allows the highlighting of the more subtle flavors of the fruit as well as making for a generally lighter taste. In some cases, grapes with higher sugar levels than usual for whites--say 26 percent--are used to make sweet white wines. Fermentation is stopped early, in order to retain some of the sugar. As little as a half a percent of residual sugar will make for a slightly sweet wine, and a percent or more will result in a sweet or very sweet wine.

Following the fermentation, the wine's pumped into other large tanks--also quite often stainless steel--and aside from topping off when necessary, tending the wine is mainly a process of moving it from one tank to another so as to leave as much sediment behind as possible in the pursuit of clarity. Meanwhile, the winemaker may blend different lots of the wine.

In most cases, the wine is bottled and sold within a year or two, and only occasionally are whites treated to small oak barrels the way reds are.

These exceptions that are aged in oak for any period are usually Chardonnays, and, to a lesser extent, Sauvignon Blanc. But a little oak goes a long way in a white wine, and while a red may spend two or three years in some kind of small oak barrel, white's will usually spend no more than a year in such a container. Two- and three year-old Chardonnays are common, but, unlike reds, more bottle aging is seldom recommended. The other exceptions are very sweet dessert wines, such as the French Sauterne; these can have very long lives in the bottle.

As with reds, most serious white wines will carry a year on the label, indicating when its grapes were harvested. Also, same as reds, some wines that lack such a date and are the result of blends of wine crushed in different years are excellent wines. A vintage date is just one of many factors that may indicate a superior product.

Making Sparkling Wines

Initially, making sparkling wines is identical to making white wines. In California, Chardonnay is usually the base wine, but in France's Champagne region, it's a blend of Chardonnay, Pinot Meunier and Pinot Noir. Since makers of sparkling wine seek to achieve a certain consistency, wines from different years, made from grapes from a variety of vineyards, may be blended in pursuit of the flavors that characterize the desired style of the producer. That's why most sparkling wines don't bear a vintage date. Occasionally, when the winemaker has, say, a superior Chardonnay one year, he or she may make a sparkling wine that's dated. But that's a special edition, and it will be released separately from the normal production.

Once the base wine is established, it's put into champagne bottles, sugar water and yeast are added, and soda-pop-style caps are placed on the tops. The bottles are stored in special racks that hold the bottles by the necks, angled slightly downward; a white mark is painted on the bottom by the edge.

Every few weeks, these bottles are rotated a quarter turn--the white mark helps keep track of the process--and the sediments within slip toward the neck. (Some makers of sparkling wine are beginning to use machines that achieve the same effect as the hand rotation.) At the same time, the newly introduced sugar and yeast start a second fermentation within the bottle; as the sugar converts to alcohol, carbon dioxide is released, creating the bubbles. This creates high pressures inside the bottles, explaining why champagne bottles are so much more heavily made than the conventional sort.

After a year or two, the sparkling wine is ready for the final touches. By now, the sediment has collected in the neck of the bottle, and it has to be removed. This is done by putting the inverted bottle in a super cold liquid that has a much lower solidification point than water; this freezes the inch or so of wine in the neck. The cold also lessens the pressure of the gasses within. As the bottle moves along the conveyor line, workers pop the tops off; there's just enough pressure inside to shoot the plug of frozen sediment out. The bottle continues to a corking machine, and then foil is added before the wire cage is attached--it insures that the cork can't blow out.

This traditional method is called "Methode Champenoise." The other way to make sparkling wine is the bulk method--the second fermentation is accomplished in large tanks and then the wine is bottled. This is considered an inferior process, so producers eschew the "bulk" designation; it's obscured with the term "Methode Charmat."

Dessert Wines

Most dessert wines are derived from white wines made from grapes with high sugar contents. While grapes for white wines are usually picked when the sugar content reaches about 22 or 23 percent, grapes for dessert wines will be allowed to mature to the maximum extent so as to get higher sugar percentages. During fermentation, the process will be stopped before all the sugar converts to alcohol, so that a substantial amount of sugar--thus sweetness--will remain in the final product.

Fortified Wines

Port and sherry are the most common fortified wines, the former produced from red wine, the latter from white. Both are associated with Portugal, and that country still produces the finest wines of either type.

In the case of port, grape alcohol is added to the young wine while it's still fermenting; this stops the fermentation process, leaving behind a substantial amount of sugar, lending to the sweetness of the final wine. It also, of course, raises the alcohol content, resulting in a wine of about 18 percent. Then it's aged in wood tanks for three or more years before bottling.

Unlike with the red wine that becomes port, the white wine for sherry is allowed to fully ferment, after which it's stored in wooden casks for several months or so. At that point alcohol is added, and depending on the style of sherry, the final product may be 16 to 18 percent alcohol. Then the solera process begins; the wine is blended in casks with wines of several other years, and this blending and aging continues for several years so that a consistent product is the ultimate effect.