Capillary electrophoresis for evaluating orange juice authenticity: a study on Spanish oranges

Fruit juices have very distinct organic acid profiles that can be used as f ingerprints for establishing possible adulteration. Recently, our group dev eloped and validated a capillary electrophoresis method using UV detection for determining citric, isocitric, tartaric, and malic acids in natural and commercial orange juices. Sample treatment consisted of only dilution and centrifugation or filtration. This method has been applied to evaluate thes e acids and their ratios in 63 samples of Navelina, the most common variety of Spanish oranges, over a three month period. This evaluation has been co nducted to establish ranges of acid concentrations and to compare them with those found in commercial juices. The more reliable parameter, because of the lower variability in fresh samples, was found to be the citrate/isocitr ate ratio with a value of 113 (RSD = 10%). Only one of nine ramdonly select ed commercial juices presented values within the range of those of the popu lation of just-pressed Navelina orange juice. Moreover, three of them had m easurable tartrate values, which is not a natural component of orange juice , showing mixtures with cheaper fruits.