Understanding Wine Acidity

Understanding Wine Acidity

Wine Acidity Acidity is a measurement of the quantity of acid present in a wine or must. This is not to be confused with the pH of a wine which is a measurement of the strength of those acids present. Like pH, however, the acidity of a wine goes a long way in determining how a finished wine will taste, feel in your mouth, and how well it will age. Having a low acidity will result in a flat and boring wine while having too much acid can lead to tartness or even a sour wine. However, if you peg the acidity just right you are much more likely to have flavors that pop, good mouthfeel, crispness in white wines, and decent ageability. It takes careful measurements and a keen sense of taste for those acids produced by spoilage organisms. More on this soon. What makes acidity tricky is that not all acids are measurable using the same laboratory methods. This is why acidity is described as three different quantities, titratable, volatile, and total. Titratable Acidity Titratable acidity, sometimes referred to as fixed or erroneously total acidity, is a measurement of the total concentration of titratable acids and free hydrogen ions present in your wine. Total acidity and titratable acidity are not the same thing and the terms should not be used interchangeably. What makes an acid titratable is its ability to be neutralized by adding a base, a laboratory process called titration. To measure this you would take a sample of wine and add to it a reagent, or indicator, which is a chemical that changes color when a specific pH is reached. With this mixture in hand a base of known pH is then added to the mixture. At some point the base will raise teh pH sufficiently to cause the reagent to change color, indicating that you’ve reached a specific pH. The amount of base added mixture required to turn the reagent to its indicator color is then translated to an amount titratable acids in the wine. The most common titratable acids are tartaric, malic, citric, carbonic acid. These acids, along with many more in smaller quantities, either occur naturally in the grapes or are created through the fermentation process. Volatile Acidity Volatile acids are different than titratable acids in that they cannot be measure through a titration but must be quantified using a steam distillation process. In this a sample of wine is exposed to steam which in turn encourages the volatile acids to leave the wine. The steam and the acids that leave the wine sample are then collected through condensation in another container. After a specific quantity of water and acids has been collected that mixture is then tested to determine the concentration of volatile acids.┬áThus volatile acidity is simply a measure of steam distillable acids present in a wine. Volatile acids are produced through microbial action such as yeast fermentation, malolactic fermentation, and other fermentations carried out by spoilage organisms. The most prominent volatile acid present in wine is acetic acid. Also of importance is lactic acid. Aside from lactic acid the...

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