How wine is made

Wine needs no added sugar or yeast in principle. Grapes arrive carrying both, and the yeast is already on the skins.

stations: 8
things upstream: 46
raw sources: 21
steps from the ground: 6

The short version

Wine is fermented grape juice. Grapes are picked, crushed and fermented by yeast, which turns their sugar into alcohol and carbon dioxide. Red wine ferments with the skins, which give color and tannin, while white wine is pressed first. The wine is then aged in tank or oak, clarified, filtered, lightly sulfited and bottled.

Pick at the right sugar

The winemaker decides when to pick using measurements of sugar, acid and pH, as well as taste. Grapes are harvested by hand or by machine.

Goes in
Wine grapes
Remove stems and crush

Machines strip the berries off their stems and gently split the skins. For white wine the whole bunches may go straight to the press instead.
Let yeast ferment

Yeast, either wild from the skins or a cultured strain, eats the sugar and gives off alcohol and carbon dioxide. Reds ferment warm, at about 22 to 25 °C, and whites cooler. Every gram of sugar gives about half a gram of alcohol.

one to two weeks

Goes in
Baker's yeast
Press the skins

For reds, the free-run wine is drained and the leftover skins are pressed to squeeze out the rest. For whites the pressing comes first. Presses ramp up gradually to about 2 bar.
Soften with a second ferment

Bacteria convert sharp malic acid into milder lactic acid in a malolactic fermentation. Most reds go through it completely, as do rich whites like barrel-fermented chardonnay.
Age in tank or oak

Wine rests for months in steel tanks or oak barrels under an airlock. Fine particles settle, and oak adds aroma and tannin. Cold storage drops out tartrate crystals.

three to six months or more

Goes in
Oak wine barrel
Fine and filter

Fining agents such as gelatin, egg white or clay bind to tannins and cloudy particles and sink out. The wine is racked off the sediment and filtered.

Goes in
Gelatin
Add sulfite and bottle

A small dose of sulfur dioxide acts as an antioxidant and antimicrobial. The wine is bottled and sealed.

Goes in
Glass bottle

End of the lineWine Next it goes into champagne.

Worth repeating

Evidence suggests the earliest wine production took place in Georgia and Iran around 6000 to 5000 B.C.
Only about 10% of all red and 5% of white wine will taste better after five years than after one year.
Gelatin is the most commonly used fining agent for removing tannin from wine.