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Chapter 5 The Impact of Sweetness and Acidity Levels in Wine and Food
can be flat and bland. White grape varietals such as Sauvignon Blanc, Riesling, and Sémillon
have higher acidity levels than Chardonnay and red wine varietals.
Much of the acidity level can be impacted by the winemaker. Decisions on when to
harvest the grapes and the fermentation process can substantially impact final perceived
acidity levels. While wine contains at least six organic acids (tartaric, malic, citric, succinic,
lactic, and acetic), the principal natural acidity in grape juice comes from tartaric and malic
acids. 14 One method for lowering total wine acidity is the process of malolactic fermentation.
Basically, malolactic bacteria use the malic acid in wine as a source of energy and convert it
into lactic acid. This process usually happens after the primary fermentation and has several
effects on the finished wine. First, because malic acid is stronger in taste than lactic acid,
wines that have undergone this process will taste less tart. Second, the malolactic fermentation
process makes wine more stable and less likely to spoil during aging. Lastly, the process
creates a compound called diacetyl; this produces the distinct buttery characteristic in Chardonnay
that has undergone the malolactic process. 15
ACIDITY LEVEL DESCRIPTIONS
The vocabulary used to describe wine acidity varies slightly from one era to the next
and between wine-drinking cultures. Words used to describe highly acidic wines include
sharp, acidulous, stinging, tart, nervy, unripe, and green. Words used to describe wines at the
opposite end, with low acidity, include flabby, flat, watery, soft, plump, and flaccid. 16 Many wine
evaluators classify wine acidity into three general categories: excessive, sufficient, and insufficient.
In addition to perceived levels of acidity in wine, acids can create positive and negative
perceptions depending on the dominant acid type that is present. For example, acidity in
wine derived from malic acid is generally associated with a sense of freshness and liveliness,
while acidity derived from tartaric acid is perceived as harsh or hard and creates a less
acceptable aftertaste at the back of the throat. 17
Table 5.3 provides descriptions and wine and food examples of differing levels of acidity.
The ‘‘Value Bands’’ column provides a range for the typical wines and food items at each
level, using a 0-to-10 scale. The ‘‘Level of Acidity’’ column provides a description of the
sensation for each category (flat through green/tart).
ACIDITY LEVELS IN FOOD
A sour taste in food can be from natural acids or from acid substances added to the
food. Aside from the desired taste of sour in food, there are several reasons why acid items
are used from a culinary perspective. Acids such as citrus or vinegar can be added to emulsified
sauces such as hollandaise or beurre blanc to change the physiochemical properties of
the emulsifying agent (allowing the protein to become more saturated with oil or fat). Acidbased
marinades are used both to flavor the food item and to tenderize it. And acid (such
as cream of tartar) is used in baking to relax the gluten in flour for many pastry applications. 18
Just as acidity in wines varies based on climate and ripeness, raw food products vary
in acidity based on where they were raised, climate, and other factors. The relative sourness
in foods is determined by the amount of natural or added sugars used in their preparation
and proportionally expressed relative to the pH scale. Cultural preferences for sour tastes in
food vary widely. Individuals have differing levels of sensitivity to sour tastes in food. Many
individuals are very sensitive, while others can detect sour tastes only when the acid level is
moderately high.