Chapter 6: Making Wines

Chapter 6: Making Wines

The major difference between the making of red and white wines is that red wines ferment with the skins and seeds of the grapes and white wines do not. Since the juice of nearly all grapes is white, it is the skins that impart color to the wine, as well as many aroma and flavor compounds. Tannin from the skins give red wine its astringency (puckery sensation in the mouth), which diminishes with bottle aging.

Red Wines
The juice of most red grapes is white. Only by coming in contact with the skins can it change color. Otherwise it will come out like a white wine. In making red wine, grapes are passed through a "crusher," a machine that de-stems the grapes and cracks their skins to allow the pulp to come in contact with the yeast. At this stage, the combination of skins, seeds, pulp and juice is called "must."  The must is then placed in a temperature-controlled fermenting tank where either a commercial yeast is added or the natural yeast is allowed to start fermentation. The pulp of the grape must stay in contact with the skins in order for it to pick up color.

When fermentation is completed the liquid is now technically wine. The mass of skins and seeds, called "lees," settles to the bottom of the fermenter. The clear wine above the lees is then drawn from the fermenting tank until all of the clear wine has been removed and only the lees and pulp remain at the bottom. This is called racking and is how most red wines are clarified before bottling. The wine may be further clarified by passing it through a filter or by use of a fining agent such as beaten egg whites. Egg whites, being positively charged, attract the free-floating sediment, which is negatively charged, and together fall to the bottom of the tank or barrel. The wine must still be racked to a clean barrel or tank in order to keep it clear. This is the gentlest technique with regard to not removing any of the flavors of the wine, just the solid particles, which can taste bitter and astringent.

If the intent is to process the wine as little as possible, regardless of any sediment that may occur in the bottle, it won't be filtered or fined. It is then aged, either in stainless steel tanks or small or large oak barrels. Wines such as these are made to age over many years, even decades. Within even 4 or 5 years of the vintage the tiny pieces of pulp that were pulverized during fermentation begin to attract each other to form sediment in the bottle. Unlike tartrate crystals (explained below), however, sediment tastes awful and must be removed by decanting or very careful pouring.

At this stage there are hundreds, maybe even thousands of choices for the winemaker. What kind of barrels do we age in?  How old should they be?  For how long?  Most red wines go through another, different type of fermentation called malolactic. Instead of yeast interacting with sugar and creating alcohol and carbon dioxide (CO2) by-products,  a bacterial culture attacks the harsh malic acid in the wine (the same acid as on the inside of green apple skin) and converts it to lactic acid (the same as lactose in milk). This lowers the wine's overall acidity and makes it a little smoother and easier to taste. Malolactic (ML) can occur normally or can be induced with natural cultures.

When ready (a matter of months or years depending on the winemaker's desire), the wine is bottled and aged further before release. Aging in the bottle develops what is called "bottle bouquet," the final melding of the grape flavors mixed with the processing techniques.

White Wines
White wines are made in a similar fashion except, in most cases, without the skin contact. After crushing, the grapes are pressed quickly to avoid contact with the skins. The tannic acid in all grape skins (red or white) adds astringency to the wine. This astringency in reds helps the aging potential. In whites this astringency may overpower the delicate flavors so very little, if any, astringency is wanted. Therefore, the pre-fermented juice is separated from the skins and seeds in a gentle centrifuge. The remaining liquid is placed in a fermenting tank or barrel, yeast is added, and fermentation begins.

Unlike red wines, white wines are fermented at very cool temperatures, sometimes between 50-60˚F. This is done to preserve the fresh fruit qualities and delicacy of white wines. Following fermentation, the new wine is clarified, then aged in stainless steel or oak barrels before bottling. Chardonnay and Sauvignon Blanc are occasionally aged for an additional time in small oak barrels to add extra nuance and complexity.

Fermentation of white wines is much longer than reds, usually requiring several weeks versus 7-10 days for reds. During each stage of winemaking, great care is taken to prevent the wine from coming in contact with air that can "oxidize" it and cause browning. Oxidation in wine is best understood by comparing it to the oxidation that takes place when one cuts an apple. It turns brown within minutes, as do potatoes when peeled.

Two additional precautions usually are taken with white wines, but seldom with reds. These precautions are called "heat stable," and "cold stable." Heat stability is nothing more than making certain, before bottling, that no yeast cells remain in the wine. If the smallest amount of yeast were present and the wine subjected to even moderate heat, it could begin to ferment even the smallest amount of sugar. It has been known to happen with sugar levels as low as .5%. Yeast cells are destroyed by heating the wine to 120˚F for 30 minutes, or passing it through a special membrane filter capable of straining out even microscopic yeast cells, or waiting until fermentation has completely stopped and all the yeast cells have expired. Most wineries choose the latter method since the heat and filtration process can remove certain nuances, which would take away from the finished wine.

Cold stabilization is often done in white wines to remove excess potassium bitartrate, a natural substance found in grapes also known  as "cream of tartar."  White grapes contain fairly large amounts of potassium bitartrate. If most of it is not removed, the wine will form crystals when placed in the refrigerator. These tartrate crystals will either cling to the underside of the cork or fall to the bottom of the bottle where they appear to be ground glass to the uneducated eye. To remove excess potassium bitartrate before bottling, the wine is placed in a stainless steel tank and its temperature dropped to about 30˚ F. The wine is held at that temperature for a period of approximately 2-3 weeks. Excess potassium bitartrate will then crystallize and drop to the bottom of the tank where it is removed either by filtration or by pumping the wine out of the tank until the hose is just above the bottom where the crystals have formed. The "cold stabilized" wine is then bottled. Some wineries prefer to skip this step, feeling that the process detracts from the wine's flavor and nuance. Having the tartaric crystals appear in the wine means nothing more than it was not cold treated and, thus, may be of higher quality.

Sulfur In Wine
Sulfur dioxide (SO2) and its derivatives, mainly sulfite agents and potassium metabisulphide, is a wonder additive used in the vineyard as well as the winery. As an antioxidant, antibacterial and anti-fungal agent, SO2 helps keep fungus from attacking grapes before the harvest during periods of high humidity. It quickly and inexpensively sterilizes bottles, barrels and other tools used in the winery. It can delay grape fermentation when there is a risk of it starting spontaneously due to a long trip to the winery.

SO2  smells like the striking of a match; indeed, sulfur is what is used at the tip. When used in the wine to prevent browning, primarily in white wines, it can leave a residual smell, which is unpleasant to many and intolerable, to a few. Most white wines, if SO2 is added, will house between 60 and 100 parts per million of sulfur. However, because SO2 is a gas, it dissipates with time in the bottle and, with swirling, in the glass as well.

Beginning in 1987 all wines with more than 10 parts per million of sulfur had to contain a statement saying so. The law allows for the term "No Added Sulfur" but that doesn't mean that it is less than 10 parts per million. In the natural occurring process of fermentation, Mother Nature will produce between 30 and 50 parts per million of "free" sulfur. For a wine to not carry the "Contains Sulfites" statement, it must be manipulated far more than other wines. These wines typically do not age well as sulfur, at this 30-60 parts per million level, acts as a preservative. An egg yoke has 5 parts per million. I guess, by law, two egg yolks should carry a warning.

The Acid Test
White wines may or may not go through ML (see earlier section for details on ML). If the total acid (TA) of the wine is such that lowering it would make it taste dull and "flabby," the winemaker may try to inhibit ML by either using sulfite agents or by lowering the temperature of the tank so that the bacteria which would begin the process naturally, can't get started. In California it is legal to add acid, but not sugar. Since we have abundant sun, sugar is not usually deficient in California wines. So, like Europe, the laws are adjusted to make life a little easier for the vintner.

The Chardonnay/ML controversy among winemakers and consumers has to do with what style a winemaker wants and the winemaker's perception of what the consumer wants. A Chardonnay grown in a cool climate, with a long growing season, may develop enough sugar to ripen, but it will also have more than its share of acid. A cool climate Chardonnay, for example, could be harvested at 23 Brix and have a .9 acid. This is quite high and the resultant acid in the wine would be very sharp on the palate. A warm climate Chardonnay could be harvested at the same 23 Brix but have a .7 acid, a fairly moderate amount. The cool climate Chardonnay might benefit from ML by lowering the total acid and replacing the normally sharp malic acid with the creamy, buttery elements, which many wine drinkers enjoy in their Chardonnay. The warm climate Chardonnay might not go through ML but, because of the lower acid, have the perception of more fruit, in this case the fruit of the grape as opposed to the flavors enhanced by the ML process.

Many people don't like ML no matter how high the natural acid is. Less than complementary terms like "green pea" and downright caustic remarks like "cat pee" have been known to invade conversations on the subject. It's a matter of taste, pure and simple. Some have it in their wines, some have it in their conversation.

Generally speaking, Chardonnays, which do not go through ML, are tighter and more shy of fruit than those that do. If a wine is well made (with or without ML) and comes from a proven vineyard site, it can  age extremely well; 10 years or more. This is not to say that ML Chardonnays don't age. Many do, but many don't. Their advantage is that they taste pretty good right away, allowing them to be sold sooner and thus bringing some income into the equation.

ML is not an either/or question. Many winemakers hedge their bets by doing "partial ML."  That means part of the wine goes through ML and part doesn't. The decision could be based on the fact that even if all the grapes come from one vineyard, all the grapes may not have reached maturity at the same rate. Sun exposure, hillside slopes, soil differences or even a day or two difference in picking can have an affect on the grapes. The winemaker must make a determination as to whether ML is appropriate for some lots and not others.

After the wine is finished, including ML, the wine's numbers will be read again. The acid will go down from what the grapes were picked at unless the winemaker adds acid during the winemaking process (legal in California). Generally a wine picked at an acid level of .8 will end up in the bottle at .65 or .7 total acid (TA).

Once the fermentation process has metabolized all of the sugar available to them and have converted the sugar into carbon dioxide (CO2) and alcohol, the wine is considered "dry." Such a wine, red or white, will taste clean and crisp in the mouth because of its lack of sugar and presence of acidity.

Terms associated with wines that are not quite dry, sometimes called "off-dry," contain residual sugar. Residual sugar (RS) refers to a percentage of sugar left in a wine by arresting the fermentation prior to a wine becoming dry. For example, a Riesling may show some degree of sweetness, but Riesling is often high in total acid and has a low pH. Therefore, to attain the desired sweetness, sufficient to override the acid, a higher amount of sugar might be needed, perhaps 3% or more. The winemaker must determine how much residual sugar is desired prior to the end of fermentation in order to assure the proper sugar/acid balance.  It is illegal to add sugar in California. In order for a wine to contain residual sugar fermentation must be stopped before all the sugar has been converted by the yeast. This decision is difficult to make if the winemaker has not worked with the same source of grapes over a long period of time. With a vineyard history of knowing how the wine should be made in order to obtain the desired results, the winemaker can be more sure of when to pick the grapes. After several vintages, the winemakers begin to get a handle on how their winemaking decisions affect the wine 2 or three 3 years later.

Chardonnay is normally a dry wine. It is also expected to be full-flavored and possess some oak or "vanilla" components which are derived from oak aging. If a winemaker is dealing with a Chardonnay of rather low pH (and the resultant higher acid), the winemaker can stop fermentation between .4% and .7% residual sugar to give the wine roundness or fatness. This procedure could result in the acid level overriding the tiny amount of residual sugar and thus the wine will taste totally dry even though it is not. Intricacies of this type, determined entirely by taste, demonstrate the great skill required by a winemaker. Assuming fine quality in the fruit and skillful winemaking techniques, "balance" is perhaps the most important aspect of a wine today.

A Chardonnay with residual sugar is generally looked down upon by the wine trade. However, a list of the top selling Chardonnays in the country will turn up quite a few that have sugar above the threshold of what is considered totally dry. Is a wine great because its RS, ML, TA, etc. are viniculturally correct or because the consumer likes it?  No book, this one included, can answer that question.


Assuming that no outside demon interferes with the finished wine, i.e. faulty corks or bacteria in the bottle before it is filled, once a wine is bottled it enters into a different phase of its life. Because of the tumultuous act of plunging this liquid into the bottle at a very rapid rate, the wine "shuts down" in what is commonly referred to as bottle shock. Some wines like nouveau, or light whites, recover quickly,  probably because there's not much to hide anyway. More robust wines, especially reds, need time to recover. Sometimes even a year or two must pass before it has the same fine flavors it had in the barrel before bottling.

As the wine ages, the flavors of the grape(s), the soil, vintage, winemaker's hand and such all combine to rearrange what you taste down the road. The small amount of air space between the cork and the bottle is all that is needed for this "reductive" transformation to take place. The interaction of acids, tannins, coloring agents and other compounds interact with the oxygen and change both the color, smell and taste of the wine. In most cases this is a positive occurrence.

The color agents in red wine begin to drop out and form fine sediment. This action makes red wine turn lighter and it begins to pick up brown hues. With advanced age it can become very brown. White wines, because they have much less coloring agents, turn color faster, becoming more golden and eventually picking up brown colors with advanced age.


A wine that tastes awful in its youth will taste awful when it's old. Too many people in the wine trade, from winemakers to retailers and the press, may extol the virtues of a very tannic wine with the saving line, "It'll age."  The fact is, if a wine is out of balance, if the tannin levels are higher than the fruit levels, it will always be out of balance. Wines do not magically attain balance in the bottle. If the wine was too high or too low in acid to begin with, it will always be so.

The benefit of aging a wine (on its side so that the cork is in full contact with the wine to avoid air getting in and wine getting out) is the coming together of all the components from discreet and separate flavors into one complete whole. The vineyard, vintage, type and length of time in oak, the acid and tannin levels, malolactic, etc. will be apparent when the wine is young. As the wine ages, these components meld together to present one united front of complex flavors with the whole being greater than the sum of its parts. Each component ages at a slightly different rate and each has its own dominance in the blend of flavors.

Normally, young red wines from noble grapes are tannic and hard. As they age, the tannin and acid levels diminish somewhat and the fruit and concentration of flavors become more apparent. It is important to understand that if there isn't enough fruit in the wine to balance the tannins, it won't magically appear later because the fruit is also diminishing. If the tannins are overpowering, even with some softening, they will always overpower the fruit and the wine will never taste harmonious. Aging is not a panacea for mediocre wine. Everything has to be there going in or there won't be anything to get out.

What is the perfect age for a wine?  That depends on the taster. The English prefer their wines (red or white) with considerable age. What a Londoner might consider a fine old claret, a New Yorker may find over-the-hill. It is as much a matter of individual taste as deciding what's a favorite white or red wine. Only by being exposed to wines of similar quality at different ages can you begin to get an idea of what your preferences are with respect to aged wines.

Wines are hardier than most people give them credit for. While a temperature-controlled cellar is the only way to store wines for extended periods of time, most of us drink our wines within a few months (some within a few hours) of purchase. A young Cabernet, or other full or medium-bodied wine (red or white), can withstand fairly brutal punishment in a few month's time and come out relatively unscathed. As wines age, however, they become more fragile. A big, young Bordeaux, for example, would probably suffer no damage if it were stored in a Chicago garage for a year versus a temperature controlled cellar. A 25-year-old Bordeaux would suffer considerably.

There are 3 important factors to consider in wine storage; temperature fluctuation, light and movement. It is more important to keep the temperature constant at 65˚F than it is to have it varying, even over a month's time, between 50˚F and 60˚F. When the wine is at a constant temperature it becomes relaxed and settles into that posture. If it is cooled down, it contracts and allows air to take up the space where the wine was. If it is warmed up, it expands and allows the wine to escape and replace the air. This continual expansion/contraction of the wine allows air to come in contact with the wine more often, thus speeding up the aging process.

Light's ultraviolet rays will cause a chemical change in the wine, spoiling it in a very short period of time. That's why wines meant for long aging are bottled in dark glass or a leaf green that helps filter out ultraviolet light.

Air pockets will form if a wine is transported or moved about often. This can have the same effect as letting more air into the bottle through expansion/contraction. This is why cellars are normally cool, dark and motionless. Humidity is a factor, but not as important a one. Within most areas of the world no humidity control is necessary. Ranges from 50% to 80% are acceptable. Too dry and the cork will dry out from the outside in and allow air inside. Too damp and it's liable to slide right out of the bottle. As with temperature though,  consistency is also the key.


You may think that you're getting more for your money if the wine is filled all the way to the top with little or no air space left in the bottle, especially if it's an expensive wine. Unfortunately, the science of wine fills says that there needs to be some air space, about a 1-inch bubble when the wine is resting on its side, for the wine to breathe. If there is no air space, even the slightest fluctuation, a degree or two, will expand the wine enough to push the cork out. It could be a problem, although in most cases, if the wine is stored well, it will reach its proper fill level and stay there as long as there is no great temperature fluctuation, light or extensive movement to interfere.