Organic Acids in the Juice of Citrus Fruits

Abstract

Organic acids of the juice in citrus fruits were determined by silica gel column chromatography in 47 samples obtained from 42 citrus species. Citrate was the major organic acid in acid citrus species and table citrus species, amounting to 75.4 to 96.9 % of the total recovered acids. Malate amounted to 55.8 to 60.1 % of the recovered acids in acidless citrus species, but 2.6 to 22.9 0o in other species. Citrate plus malate amounted to 78.3 to 99.7 % of the total recovered acids. Acetate, pyruvate, and oxalate were detected inn more than half of the samples. Group I acids, a mixture of glutarate, fumarate, and formate and group II acids, a mixture of lactate, succinate, and a-ketoglutarate were detected in all the samples. However, the sum of these minor organic acids was less than 2 % of all the organic acids detected, except for three samples. There were more kinds of organic acids in acidless citrus species, sweet oranges, and mandarins than in sour orange, tangors, pummelos and grapefruits, yuzus, and pum- melo hybrids. However, there was no correlation between the number of organic acids detected and either the sum of detected acids or the total acidity of juice.