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 as he major organic acid in acid citrus species and table citrus species, mounting to 75.4 to 96.9% of the total recovered acids. Malate amounted to 55.8 o 60.1% of the recovered acids in acidless citrus species, but 2.6 to 22.9% in ther species. Citrate plus malate amounted to 78.3 to 99.7% of the total ecovered acids.
Acetate, pyruvate, and oxalate were detected in more than half of the samples.Group I acids, a mixture of glutarate, fumarate, and formate and group I acids, a mixture of lactate, succinate, and α-ketoglutarate were etected in all the samples. However, the sum of these minor organic acids was ess than 2% of all the organic acids detected, except for three samples. There ere more kinds of organic acids in acidless citrus species, sweet oranges, and mandarins than in sour orange, tangors, pummelos and grapefruits, yuzus, and ummelohybrids. However, there was no correlation between the number of organic cidsdetected and either the sum of detected acids or the total acidity of juice.