Acid and Winemaking

A. Acid types

1. Tartaric – one of the major acids in ripe grapes, typically 70% - 90% of total acid (best acid for wine structure).
2. Malic – minor acid in ripe grapes, 10 – 30% of total acid; more if not ripe (very tart acid.  Add to reds if malo-lactic fermentation is desired).
3. Lactic  - formed with the innoculation of a bacteria to transform malic acid into lactic acid, which gives a softer, fuller mouth feel, usually accompanied by a buttery flavor and a loss of fruitiness (often used in chardonnay and some reds)
4. Citric – one of the acids found in grapes, in small quantities which gives a fresh citrus character to the wine.  If too much is used, the wine becomes acetic.

B. Addition of Acid

Before fermentation use acid blend, which is a blend of 40% tartaric, 40% malic and 20% citric acid.  Do not use citric acid by itself before fermentation.

After fermentation and stabilization – citric acid can be added before bottling, if needed.  Tartaric acid may crystallize and malic acid may go through malo-lactic fermentation unintentionally).

C.  Values

Dry Red: 0.6 to 0.7% acid

Dry white: 0.65 to 0.75% acid

Semi-dry red/white: 0.75 to 0.85% acid

Sweet red/white: 0.85% to 0.90% acid

It is very easy to add acid but very difficult to remove.  Be careful when adding.  You may want to adjust your acid in the juice to the lower end of the value and adjust upward after fermentation. 

One teaspoon of acid blend will raise the acid level by .15 grams per gallon

Formula for Adding Acid

Acid Level Desired minus Acid Level of Must = ___ divided by .15 = number of teaspoons of acid blend required per gallon.

Example:

(Desired level) .7 minus (must level) .42 = .28 divided by .15 = 1.86 teaspoons of acid blend to add per gallon.

For 5 gallons of must multiply 1.86 x 5 = 9.33 teaspoons of acid blend.