How White Wine is made

In a nutshell

Once white grapes are picked from the vineyard and are taken to the winery, the winemaking process starts. In the wine industry, the grape juice that comes out of the press is called “must”. The must is fermented and turns into wine. The wine then is aged, clarified, fined, filtered or both and bottled. Read about our white wine recommendations with our White wine 101 guide [link to article]

Phase 1: Harvesting of the white-wine grapes

White wine grapes are carefully monitored. The winemakers will take sample from the vineyard and check for sugar levels, and very often acidity pH and aromas.

Once the grape sugars and acidity have reached the perfect balance, the grapes are picked and transported to the winery. White wine grapes are commonly harvested at night or early in the morning because cool grapes preserve freshness.

Harvesting can be done either by hand or by machine. Machine harvesting is fast and reliable. On the other hand, sorting is far easier when harvesting by hand, to ensure only the very best grapes reach the winery.

Phase 2: On the way to the press - Destemming and Crushing of the grapes

There are many ways a winemaker can handle the grapes.

One option is to load the press with whole bunches. Others may choose to destem and crush the berries before loading which leads to more juice extraction and less bitterness from the stems.

Before pressing the must, the winemaker might decide cold macerate the must. This is when the must is stored in low temperatures, in order to extract more aromatics from the grapes.

Phase 3: Pressing of the grapes

Many types of presses can be used for white wine, but the most common one is the pneumatic press.

The grapes are squeezed with the help of a membrane and air pressure. It is a very gentle process.

When making fresh and fruity wines, like those found in Friuli, in Northern Italy, these presses work without oxygen so that all the flavours are protected.

Phase 4: White wine fermentation

Once the grapes are pressed, the must will settle overnight so that any bigger particles like seeds and dust can be removed.

The winemaker can choose to wait for the fermentation to start by itself with the yeast population that came from the grapes, but some will see this as risky. Most commercial wineries will use ready yeast cultures to ensure a healthy fermentation.

The fermentation is complete once all the sugars have been transformed into alcohol. This usually takes two to three weeks.

Phase 5: Malolactic Fermentation (MLF)

Malolactic fermentation (MLF) is the process where malic acid turns into lactic acid. It happens after alcoholic fermentation and is performed by lactic acid bacteria, not by yeast.

Lactic acid is more smooth-tasting than malic acid, so the wines become smoother and more approachable. It is particularly used in colder climates where wines have high acidity. MLF can produce butter, yoghurt and brioche flavours which the winemaker may want in their white wines.

Phase 6: White wine racking

After fermentation, dead yeast cells will slowly falls towards the bottom of the tank creating sediment. This is called wine lees.

They have to be removed, which is done by pumping the wine into another tank, taking care not to include the sediments at the bottom. This process is called wine racking.

Sometimes, it is beneficial for the wine to leave the finest of the lees in the wine after racking since they help to give more body to the wine.

Phase 7: White wine ageing and maturation

White wine can be sold as soon as right after fermentation is complete. However, almost all wines spend some time maturing. The wine evolves during this period and becomes more stable.

The ageing of the wine can happen in any vessel. Stainless steel tanks are most commonly used, as are oak barrels. Now experiments are made with concrete tanks and amphoras.

The word “Riserva” is often written on wine labels. It indicates that the wine has been matured for more than just a few months, usually in oak barrels.

Phase 8: White wine blending

Blending is an extremely important step of winemaking since it helps create complex and balanced wines.

For single varietal wines, this is achieved by the blending of different vineyards. A producer can also choose to blend different varieties together. Perhaps the most iconic blend of the wine world is the white Bordeaux blend of Sémillon and Sauvignon Blanc.

In Italy, multi varietal white blends can be found in many places. One example is Sicily’s Bianco d’Alcamo, which is a blend of Catarratto with other local varieties like Grillo and Ansonica.

Phase 9: White wine stabilisation

Before wine goes into the bottle, the winemaker has to make sure it is stable. There are three main instabilities in white wine.

Tartaric acid - a chemical instability, leads to tartaric crystals inside the bottle. It can easily be avoided by cooling down the wine and filtering.

Protein instability - This can create haze in the bottle. Even though it doesn’t affect wine taste, the wine becomes unattractive. The problem is overcome by fining the wine with bentonite which binds to the proteins before being filtered out.

Finally, microbiological instabilities (mainly refermentation) are combated by the addition of Sulphur Dioxide in the wine.

Phase 10: White wine bottling

The wine is now ready for bottling. Any type of vessel can be used, although 750 mL glass bottles are preferred.

Traditionally in Europe, cork is used for sealing. However, especially for those white wines that are meant to be enjoyed fresh, screw cap closure can be ideal.

The freshly bottled wine is usually left to “rest” before being sold. A few white wines are aged for many years by the producer. Bottle ageing particularly suits the Fiano variety of South Italy.