How to Make Wine
How to Make Wine
The Process and Steps in Winemaking
Whole libraries have been written about the winemaking process. For a quick summary, we've put together this overview of the basic steps in table wine making.
Here's the basic process:
1. Decide on the type and style of your wine
2. Choose the grape variety
3. Buy land and plant grapes in a region that will support the kind of wine you want to make / OR / buy the grapes from someone with vineyards already in that region
4. Pick the grapes at the peak of ripeness
5. Sort the grapes
6. Extract the juice
7. Ferment the juice
8. Mature the wine
9. Blend and finish the wine
10. Bottle the wine
11. Bottle aging
Three quick points:
-- Grapes are unique among fruits because they have sufficient sugars and acids to create enough alcohol to make an agreeable wine, and to protect wine against quickly spoiling.
-- The ability to make the wine you want depends on your knowledge of grape growing and basic agriculture, as well as the biological and chemical factors in winemaking.
-- "Wine is made in the vineyard, not the cellar"
The type and style of a wine can range from a quick, simple young wine to a work of winemaking art made from the finest grapes and vineyards. A grape's color quality and vineyard location will each have an effect on the wine's quality.
Other factors that affect the type and style of the wine
- Red wines must come from dark-skinned grapes because it is the color in the grape skins, not the juice, which determines a wine's color. This means that red wines are made from dark-skinned grapes and also the skins of those grapes.
- White wine grapes must be pressed of their juice before being fermented so that the juice will not be in contact with the colors and tannins in the grape skins.
- The climate and vineyard location of grapes will affect the wine's style
- The ripeness of grapes can determine a wine's style:
- Under-ripe grapes will have undeveloped sugars, and will be high in acids: this is especially good when making sparkling wines and champagnes.
- Very ripe grapes are full of sugars, making them good candidates for sweet, dessert and fortified wines.
Choosing the grape variety is dependant upon the style of wine wanted, and where one's vineyard (if any) is located.
Generally speaking, white wine grapes such as Chardonnay, Chenin Blanc, Colombard, Gewürztraminer, Riesling and Semillon prefer cooler climates, and red wine grapes such as Barbera, Brunello, Cabernet Sauvignon, Cabernet Franc, Malbec and Merlot prefer warmer climates.
The right dirt and the right climate for a grape variety are some of the most important decisions in fine winemaking. Winemakers have discovered the climates, soils and types of sun exposure that particular grape varieties prefer.
To assure quality wines from year to year, winemakers must grow or buy grapes from vineyards that have the necessary characteristics to create premium wines.
Grapes ripen once a year in late summer or fall, and picking at the perfect moment is a race against time. Once the decision has been made to pick, the grapes must be delivered to the winery as fast as possible to minimize crunched grapes, oxidation and the loss of fresh, fruity flavors due to heat. In hotter climates, grapes will even be picked at night by machines to speed delivery to the winery.
Picking grapes in cool climates happens just as soon as grape sugars reach adequate levels; in warm climates grapes are picked just before acids begin to plummet and pH skyrockets. To gauge ripening, broad ranges of samples are taken from different parts of the vineyard to allow for variations in soils, temperature and climate. The sugar levels of these samples are then tested using refractometers or hydrometers to estimate degrees Brix (sugar content).
Ultra premium winemakers add to this scientific style by also approaching ripeness in a sensual way: they walk the vineyards looking for the blush of ripeness in the grape's skins, its willingness to pull away from the stem, its ripe flavors and scents. It's worth the effort: fully ripe grapes impart a softness and complexity to wines that is seductive.
Sometimes grapes are sorted along a conveyor belt because a rainy year has produced rotten fruit, a cool year has produced unripe fruit, or a scorching year has produced, well, raisons. This isn't (thankfully!) always necessary, and many years the minor variations in fruit ripeness aren't an issue.
Here's where winemaking begins! There can be 6 parts to removing the juice:
- Destemming: stems and leaves are removed to eliminate the harsh and astringent qualities they can add to a wine - this is sometimes done at the same time as crushing
- Crushing: the grape skins are broken to allow the juices to flow - Note: some wines aren't crushed, but made from whole grape clusters. These include most quality sparkling wines, botrytized sweet wines, some fine red wines and wines fermented using carbonic maceration.
- Sulphur dioxide: To prevent wine spoilage and oxidation (browning of white wines and deterioration of aroma and flavors) sulphur dioxide and/or enclosed tank presses are sometimes used.
- Skin Contact: This adds varietal aromas, flavors and color to a wine. The floating cap of skins on the surface of the juice is punched down once or twice a day with a perforated board, or juice is pumped over the cap to maximize juice/skin contact and extract color and flavor.
- Pressing: After skin contact or immediately after crushing, the must (juice, seeds, stems and seeds) is pressed to extract more juice. The lightest pressing is called free-run juice. All later, increasingly heavy, pressings are called press juice. Free-run juice is the best: it has more sugar and less acid and tannin, resulting in wine that is less coarse.
- Cooling: the juice is sometimes cooled in a heat exchanger to 45-60 degrees F. This preserves fresh, fruity flavors and discourages damaging bacteria and oxidation
- Additions: In a perfect world, all grapes are healthy and ripe and need nothing but their sweet selves to make great wine. Alas, this imperfect world frequently hands out underripe, overripe and even rotten grapes. Enter additions! Sulphur dioxide has been used since Roman times to preserve, disinfect and ward against oxidation. Some individuals react badly to its presence in wine. Sugar is added (called "chaptalization") to underripe grapes from cooler growing regions that may not have growing seasons long enough to properly ripen grapes. Tartaric acid is frequently added to grapes that have been allowed a long, flavorful ripening period that has reduced their natural acids.
- Composting the pomace: the grape solids that remain after pressing are called pomace, and are frequently added back into the vineyard soil as an amendment
Fermentation in wine is a chemical change caused by the action of yeasts, which includes the production of heat when the grape sugars are converted to alcohol. Fermentation is a part of so many good foods! Bread, cheese, yogurt, sauerkraut, beer and wine are all examples of common foods that include fermentation in their creation.
- Yeast types: The yeasts able to create fermentation can be found swimming in the air of all established wine growing regions. For many winemakers this is enough. They simply wait a few days for the multitudes of local yeasts to begin their transformation of the juice. Other winemakers prefer to work with cultured yeasts for the predicable results this the fermentation process. The local yeast users argue that a wider range of yeasts contribute a wider range of flavors. The debate rages!
- Fermentation containers: Most modern fermentation containers are made from stainless steel because it's easy to clean and cool. But wine can be fermented in just about anything: wooden, stone, concrete or plastic vats. Large wooden vats, a European tradition, retain heat (good for extracting color from grape skins) and "breathe" in a way that is impossible for non-porous stainless steel.
- White wines are generally fermented in tall, narrow closed tanks, but red wines are fermented in wider, open tanks to maximize the area of the cap and to allow ready access to the cap for punching down or pumping over. (See Six: skin contact, above)
- Fermentation produces heat. The larger the container used to ferment, the more difficult it is to control the heat. If the heat generated by fermentation is not carefully supervised, it can destroy desirable flavors in the wine.
- Warm or cool fermentation: The huge amounts of heat generated by fermentation can kill the yeast, resulting in a "stuck" fermentation. Cooling methods are the key to controlling stuck fermentations, as well as wine flavors and character.
- White wines are generally fermented at cooler temperatures. Temperatures range from 50 to 60 degrees F and fermentation finishes in two to six weeks.
- Red wines are fermented at warmer temperatures - between 60 to 90 degrees F - and can take over a month to finish fermentation.
- Europeans ferment at the higher temperature ranges for both white and red wines to take advantage of the complex aromas that can arise from warmer fermentations.
- Racking: After fermentation has finished, the dead yeast cells fall to the bottom of the tank and form a layer of sediment called yeast "lees". Generally, the wine is transferred to clean tank to remove it from the lees, and this process is known as "racking". Some wines are allowed to remain in contact with the yeast lees to add yeasty odors, complexity and body to the finished wine.
- Malolactic, fermentation: Most red wines and some whites go through a second fermentation that converts the malic acid in the grape juice to lactic acid and carbon dioxide gas. The lactic acid (also found in milk) is less tart than the malic acid and adds stability, softness, fullness and complexity to the wine. Malolactic fermentation adds a lovely buttery flavor to wine as it ages.
The new young wine is now a cloudy, yeasty, liquid that can't be stored for very long. To transform it into the beverage we love, it needs to be clear and have the ability to age gracefully. If one has the time, aging the young wine in small oak barrels can clarify and stabilize it in a natural manner. The more time the wine has to settle this way, the less clarifying additives will be needed. Wood aging also imparts the flavor, color and tannins from the wood to the wine.
However, it is cheaper, and easier to cool and clean stainless steel, and so less than 10 per cent of all the wine produced in the world is aged in small barrels. But ah, the results when it is!
Common clarifying / stabilization steps
- Racking (see above)
- Centrifugation to use gravity to pull particles from the wine
- Filtering clarify and sterilize
- Cold-stabilization through chilling to prevent tartrate crystals from forming
- Fining additives (see below) to clarify and balance
Commonly used additives
- sulfur dioxide to protect the wine from oxidation and refermentation
- gelatin to reduce astringency
- egg albumen to reduce astringency
- ascorbic and sorbic acid to preserve / act as anti-microbials
- tannin to clarify
- bentonite to produce heat stability
- casein to clarify and reduce color in white table wines
- PVPP to remove brown pigments
For very little or no oak aging wines are fermented in stainless steel tanks followed by a short period (three months or less) in very large 500-2000 gallon oak barrels.
For moderate oak aging wine is fermented in stainless steel tanks followed by a 3-4 month period in 60-gallon oak barrels with medium toast.
For heavily oaked aging wine is fermented in oak barrels, followed by aging for up to a year for white wines and two years for some Cabernet Sauvignons in 60-gallon French oak barrels with medium toast.
Wines are blended for balance or to augment their complexity, or correct faults. This can be done by interplanting different grape varieties and harvesting and crushing them together, or by separately crushing, pressing, fermenting and aging several different grape varieties and adding them together before bottling.
Laws that govern wine blends in the U.S. include
- Table wine must have an alcohol content of 7-14%
- To carry a vintage date, 95% of a wine's grapes must be harvested in the vintage year
- To carry a varietal name, 75% of the wine must be made of that varietal
Some Common Varietal Blends
- Chardonnay / Pinot Blanc
- Sauvignon Blanc / Semillon
- Cabernet Sauvignon / Merlot / Cabernet Franc / Petit Verdot / Malbec
- Malvasia / Trebbiano
- Marsanne / Roussanne / Viognier / Rolle
- Merlot / Cabernet Sauvignon
- Zinfandel / Petit Syrah
- Sangiovese / Cabernet Sauvignon
- Syrah / Grenache / Cabernet Sauvignon / Viognier
- Tempranillo / Mazuelo / Graciano / Viura / Cabernet Sauvignon / Merlot
With a clear idea of what they want their final wine to taste like, winemakers blend different batches of wine and then taste the trial mixtures, deciding what works and what doesn't. Some of the elements that winemakers will be balancing will be sugar levels, and aged, oak, malolactic, and yeast contact flavors. Although a problem batch of wine can be improved with additions from better wines, a good wine can be ruined with even a small addition of an inferior wine.
Bottling wine is a struggle for maximum control over spoilage. As a result, sterilization is present at every stage in the bottling line.
Empty bottles arrive by the 12-bottle case and are washed, rinsed and sterilized to prepare them for being filled with wine. As the bottles travel down the line to be filled, every piece of machinery has been sterilized to help prevent contamination. After the bottles are filled with wine, many wineries blow an inert gas onto the wine's surface to create a vacuum to minimize the addition of any air. Immediately after being filled, the bottles are closed with corks that have been treated with sulfur dioxide to kill any possible yeasts that could create spoilage. At the next step on the bottling line, the bottles are labeled, their corked necks are covered with plastic or metal capsules and they are put back into their boxes for bottle aging.
Bottle aging can last anywhere from a few days to several months to decades for some Cabernet Sauvignons. Storage conditions at this point are the same as for any cellared wine: dark, vibration-free with constant cool temperatures ranging from 50 to 68 degrees F.
All wines improve with time in the bottle. Partly, wines need some time to recover from the "bottle shock" that happens from being bottled, but even after that short period, most wines will continue to improve for many years, after which it will begin to decline rapidly in quality.
Do you need information about this part of the process? ...Didn't think so!