fixed acids, those organic acids of wines whose volatilities are so low that they cannot be separated from wine by distillation. The two main fixed acids of wine are tartaric acid and malic acid, but several other non-volatile acids are present in small amounts. Unfortunately, the distinction between fixed and volatile acids is not precise because there are some acids which have intermediate volatilities. Among these are lactic acid and succinic acid, both found in wine. The fixed acids are important in wines because they are the acids that give wine its refreshing tartness, as well as its natural resistance to bacterial attack. volatile acids, on the other hand, are more obviously smelly than fixed acids and generally produce fruity or, when present in excess, vinegary aromas. total acidity, a standard wine measurement, is the sum of the fixed acids and volatile acids.