Acid Blend, powder. This is a mixture of tartaric, malic and citric acids in a 40-40-20 ratio. Its use is often prescribed in wine recipe books and used primarily for fruit wines (non grape). A single one or a combination of two of these acids will work about as well.
Ascorbic Acid is an anti-oxidant used as a partial substitute for sulfur dioxide, or used to prevent oxidation, which creates a dull and unpleasant flavor, and to prevent discoloring in the final product. Recommended for wines that discolor easily.
Ascorbic Acid, like Copper Sulfate, is often used to treat hydrogen sulfide (H2S) or ‘mercaptans’, which presents as a rotten egg scent in your wine. Try treating first with Copper Sulfate but if the problem persists, then treatment with Ascorbic Acid will be necessary. If you have advanced H2S ‘disulfide’, the scent could be described as burnt rubber or garlic-like and the wine will not improve with the treatment of Copper Sulfate alone. The use of 0.25gm Ascorbic Acid per gallon will often help by converting the disulfides back to mercaptans. The process may take up to three weeks, after which the wine should be treated with Copper Sulfate.
Both malic and citric acids are used to acidulate other fruits (commercial wines can legally only add acids that occur naturally in any particular fruit).
This acid is found almost universally in temperate fruits. It dominates in apples and together with tartaric acid accounts for most of the acid in grapes. The main disadvantage of malic acid is that it buffers to a fairly high pH.
The form of commercially available malic acid added to wines is not subject to M-L fermentations.
Helps to control the acidity of your wine. Since it is the primary acid component found in grapes, winemakers can adjust the acidity of their wine by adding tartaric acid to the wine.
Tartaric acid is the characteristic acid of grapes which is found in no other common fruit. Low acid grapes from warmer climates will benefit from its addition; the wine will clear more readily and will keep and taste better. It buffers to a nice low pH. Wines with acidity below 0.5% will benefit from its addition. It takes about 3.7 grams per gallon to increase acidity by 0.1%. Best practice is to add tartaric very early in the process.