Changes in organic acid composition of citrus juices during the 2000-2001 season

Paul F. Cancalon, Yehong Xu

Abstract


Both orange and grapefruit juice contain significant amounts of organic acids. Two, malic and citric acid, are present in large quantity. The third one, isocitric acid, is present in the juice in very small amounts but is particularly important in determining the authenticity of citrus juices. In the present study, samples of orange and grapefruit juices were collected between October 2000 and June 2001 and analyzed for organic acids by capillary electrophoresis with conductivity detection with a method developed previously. Changes in organic acid levels were compared to the variations in Brix/ acid ratio and acidity. For isocitric acid, the same pattern was found for each of the three orange varieties: the ratio varies in opposite manner as compared with isocitric acid. High acid levels and low ratios are found in the early fruit and the opposite become true for mature oranges. In the case of grapefruit juice, the same inverse relation between isocitric acid levels and ratio was also seen. However, since there are no varieties maturing successively, the high level of acid recorded early in the season fell rapidly.

Keywords


capillary electrophoresis; citrate; isocitrate; citrus; organic acids

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283