Pre-Fermentation Treatments
Acidity/pH Adjustments
Juice and must that fail to possess the desired acidity and pH may be adjusted before fermentation. No precise recommendations for optimum acidity and pH values are possible. Nevertheless, the acceptable range for total acidity in most wines is generally between 5.5 and 8.5 mg/L (Jackson, 2008). White wines are generally preferred at the higher end of the scale, whereas red wines are more appreciated at the lower end. For pH, a range of between 3.1 and 3.4 is favored for white wines, and between 3.3 and 3.6 for most red wines (Jackson, 2008).
Climate
In warmer climates such as Southern Europe, California, Australia, and South Africa (Figure 3.1), it generally requires increasing the titratable acidity, or the more critical situation of lowering the pH (Section 19.3). In the cooler climates of the world such as Northern Europe, Eastern United States, and Canada, acidity adjustment generally requires a reduction in titratable acidity so that the resulting wine will be acceptable (Section 19.4).
Wine Style
In general, white wines exhibit more acidity than red wines. Acidity gives wine its crispness on the palate. A dry wine needs acceptable levels of acid to provide liveliness and balance; sweet wine needs acidity so it does not seem cloying. Too much acidity will make the wine seem harsh or bitter; too little and the wine will seem flabby and dull. Lighter-style red wines may have high acidity, while heavier-bodied red wines tend to have low acidity. Acidity is not only important in protection from microbial spoilage but also in producing a clean fresh taste and favoring color stability, and is crucial to proper aging of wine.
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