Organic acids are major components of fruits. The acidity of fruits arises from the organic
acids that are stored in the vacuole, and their composition can vary depending on the type
of fruit. In general, young fruits contain more acids that may decline during maturation
and ripening due to their conversion to sugars (gluconeogenesis). Some fruit families are
characterized by the presence of certain organic acids. For example, fruits of Oxalidaceae
members (ex. Starfruit, Averrhoa carambola) contain oxalic acid, and fruits of the citrus
family, Rutaceae, are rich in citric acid. Apples contain malic acid and grapes are characterized
by the presence of tartaric acid. In general, citric and malic acids are the major organic
acids of fruits. Grapes contain tartaric acid as the major organic acid. During ripening, these
acids can enter the citric acid cycle and undergo further metabolic conversions