This is an overview of wine production-including harvesting, fermentation, aging, and bottling.
In the northern hemisphere, grape harvest takes place between August and November.
By machine: In many cases, the grapes are mechanically harvested by a machine. Mechanical harvest is common for large vineyards on flat land.
By hand: In some cases, grapes are harvested by hand. This can be the case for vineyards grown on slopes or land that machines cannot access, and for premium wines that require careful grape selection.
What is Fermentation?
Fermentation is the process in which yeast converts grape sugars into alcohol, carbon dioxide, and heat – transforming grape juice into wine.
Wild (ambient) yeast exist naturally on grape skins, stems, and even in the winery itself. A winemaker can choose to use these naturally-present yeasts to complete the fermentation process, or add yeast to the juice (most common). The grape juice temperature must be adjusted to the right setting in order for yeast to begin and continue their job.
Over the course of several weeks, the yeasts consume the grape juice sugar and replace it with Carbon Dioxide and Ethanol (alcohol). Once the yeasts consume all the sugar, they die and are filtered out of the wine. However, if the winemaker were to remove the yeasts before all the sugars were consumed, the wine would remain sweet with lower levels of alcohol.
Sometimes a wine-maker allows the wine to mix with the dead yeast for an extended amount of time, imparting additional flavors and making the wine more complex.
White Grape Fermentation
White grapes are gently pressed to release clear juice, the skins are discarded, and the remaining grape juice begins fermenting in cooler temperatures to retain acidity and delicate flavors.
Black Grape Fermentation
Black grapes are usually not pressed upon arrival, but fermented with their skins. Warmer temperatures help to extract flavor, tannin and color from the black skins.
When fermentation completes, the grapes are pressed to drain the new wine, and the skins are discarded.
Bottling and Aging
In many cases, the wine is quickly bottled, and sent to market for immediate consumption.
Other wines undergo aging before they are bottled. This could be to soften the grape tannins, integrate the flavors, and improve over time. Aging wine in new oak barrels will also impart sweet and spicy notes into the wine and allow oxygen flowing into the barrel to create even more flavors.
The longer a wine is stored in a winery, the higher the final cost of the bottle.
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