Definition - What does Deacidification mean?

Deacidification, is a process that is used to remove excess fruit acids from wine. All fruits contain a specific amount of acid and grapes are no exception. Most grape acids are removed during the biological ripening process when the grapes increase sugar levels and decrease acidity.

Acidity for wine is in reference to the taste difference between tart, sour, dry to sweet, buttery, or smooth. Any leftover acid in the must/juice or wine is adjusted to balance its acidity and pH either before or after the fermentation process.

The acid level can depend on grape variety, type of soil, differing climates and the rate of respiration. Grapes grown in colder climates have a slower ripening process, which produces higher levels of acid. Grapes grown in warmer climates have a faster ripening process, which decreases most biological acids and must have acid added back into the must. Winemakers use these variables to pick the grapes at a certain time, to deacidify the must or add acid if needed, dependent on the type of wine being grown and made.

WineFrog explains Deacidification

Three very influential biological acids in must/juice pre-fermentation include Tartaric, Malic and Lactic Acids and each impact the wine and grapes differently. In most cases, wine is deacidified before fermentation because chemical adjustments are easier to make during the juice/must stage.

The four common deacidification before the fermentation processes are:

  • Adding carbonates (calcium or potassium) to the must to adjust its acid and pH levels.
  • Ion-exchange, a technology based removal, is used to break down the acid with an ion and/or cation ions in a steel cylindrical device.
  • The third method is called amelioration - using water to dilute the acid. This can be done before or during fermentation.
  • Finally, deacidification by blending, which is achieved by mixing two or more wines together and used to balance out the acid, not enhance the flavors. Blending is the least preferred of the four because of the many limitations its process poses like wine availability and content restrictions.

Deacidification after fermentation is reserved for smaller adjustments. Any changes made post-fermentation are harder to control and have more impact on the flavor of the wine. Adding potassium carbonate and amelioration are two ways to adjust the acidity after fermentation. In some cases, acute acid corrections are recommended after alcohol is added, after the MLF process or just before bottling. Two less common ways include double salt deacidification and fermentation with acid-removing yeast.

The deacidification process is used most for grapes from colder regions; Canada, the Northwest region of the United States, New Zealand, and Germany. Grapes grown in northern climates biologically ripen at a slower pace, reducing the amount of acid removed through ripening and deacidification after picking.

For taste, softer, buttery flavors come from deacidified wines. Most red wines are deacidified and whites have a different acidification process. However, oaked Chardonnays are the exception and are deacidified to produce a softer flavor.

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