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Wine Making 2
During this primary fermentation, which often takes between one and
two weeks, yeast converts most of the sugars in the grape juice into
ethanol (alcohol). After the primary fermentation, the liquid is
transferred to vessels for the secondary fermentation. Here, the
remaining sugars are slowly converted into alcohol and the wine
becomes clear. Wine is then allowed to age in oak barrels before
bottling, which add extra aromas to the wine, while others are
bottled directly. The time from harvest to drinking can vary from a
few months for Beaujolais nouveau wines to over twenty years for top
wines. However, only about 10% of all red and 5% of white wine will
taste better after five years than it will after just one year.[1]
Depending on the quality of grape and the target wine style, some of
these steps may be combined or omitted to achieve the particular
goals of the winemaker. Many wines of comparable quality are
produced using similar but distinctly different approaches to their
production; quality is dictated by the attributes of the starting
material and not necessarily the steps taken during vinification..[2]
Variations on the above procedure exist. With sparkling wines such
as Champagne, an additional fermentation takes place inside the
bottle, trapping carbon dioxide and creating the characteristic
bubbles. Sweet wines are made by ensuring that some residual sugar
remains after fermentation is completed. This can be done by
harvesting late (late harvest wine), freezing the grapes to
concentrate the sugar (ice wine), or adding a substance to kill the
remaining yeast before fermentation is completed; for example, high
proof brandy is added when making port wine. In other cases the
winemaker may choose to hold back some of the sweet grape juice and
add it to the wine after the fermentation is done, a technique known
as süssreserve.
The process produces wastewater, pomace, and lees that require
collection, treatment, and disposal or beneficial use.
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