Measuring the amount of vitamin C in citrus fruits by atwo step oxidation

Background and purpose:Epidemiological evidence has suggested that consumption of fruits reduces the risk of chronic diseases such as cancer and cardiovascular disease. These benefits are often attributed to their high antioxidant components such as vitamin C (ascorbic acid). Citrus species are extremely rich sources for this vitamin, therefore we decided to determine the amount of vitamin C in some citrus fruits.Materials and methods : 13 species of commonly used citrus fruits were collected at the ripening stage. All the trees were cultivated in the experimental fields, Fajr citrus experimental institute. The vitamin C contents in fresh juice were determined by a two step oxidation-reduction titration. Data were analyzed using one-way analysis of variance (ANOVA) followed by tukey, multiple range test.Results : Mean ascorbic acid contents of commonly used citrus were 85.4±18.3 mg/100 of juice (ranging from 57.9 to 131.6). The highest amount of vitamin C were found in Shahsavari orange 131.6 ± 4.2 and Sanguinello 100.7 ± 2.2 and the lowest amounts were in Tangelo 57.9 ± 2.3 and Unshiu 70.2 ± 2.2 mg/100 of juice. There was no correlation between Ascorbic acid contents and amount of citric acid in juice.Conclusion : Significant differences were found in vitamin C contents of citrus fruits. In order to increase the intake of vitamin C in daily diet, consuming fruits with higher contents of vitamin C is recommended.