Juice and Wine Acidity
Acidification of Must and Wine
In warm climates, including parts of southern Europe, California, South Africa, and Australia that have longer ripening seasons and/or higher mean temperatures (16°C, 61°F and above), a considerable amount of malic acid is degraded during maturation. Heat, especially at night, reduces acidity in the grapes. This is especially a problem with young vines. Preferred ranges for pH and titratable acidity are conducive to development of optimal wine flavor during alcoholic fermentation, and it inhibits the proliferation of spoilage yeasts and undesirable lactic acid bacteria.
Acidification Correction Methods
Acidification is the process of increasing the total acidity (TA) of must and wine, leading to a decrease in pH. The general consensus is that acid correction should be done before starting the fermentation rather than on the wine.
Blending
Blending with other must (high acidity and low pH) is the best method, whenever possible. However, in many cases, it is not practical. It may be difficult to find the right grapes with the desired pH and titratable acidity at exactly the time of crushing and starting fermentation.
Acid Addition
Addition of acid means generally to increase the TA and/ or decrease the pH. Typically, the acids of choice are tartaric, malic, citric, or lactic; each has its advantages and disadvantages. Some winemakers feel that acid additions are best made using combinations (ratios) of malic and tartaric acids that approximate those of grapes grown in their areas (Zoecklein et al., 1995).
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