Ascorbic Acid, Total Phenol Content and Antioxidant Activity of Fresh Juices of Four Ripe and Unripe Citrus Fruits

Abstract

The ascorbic acid and total phenolic content to antioxidant activity of fresh juices of four ripe and unripe citrus fruits namely Citrus limon, C. reticulata, C. sinensis and C. aurantium were compared. The fruits were collected from local market and the pulp and seed free juices were collected. The pH and total acidity were determined. Ascorbic acid content and total phenolic content of fresh fruit juices were determined by volumetric and Folin-Ciocalteu reagent method respectively. Antioxidant activity of fruit juices was determined by two in vitro assays namely DPPH free radical scavenging assay and Ferric reducing assay. The pH was lesser in unripe fruit juices. Acidity, ascorbic acid and total phenolic contents were high in unripe fruit juices. Ascorbic acid and total phenolic content was high in C. aurantium and C. sinensis respectively. In DPPH assay, C. limon, C. reticulata and C. sinensis exhibited stronger scavenging potential when compared to C. aurantium. Ferric reducing potential was higher in C. sinensis followed by others. Overall, unripe fruit juices have displayed stronger antioxidant activity when compared to ripe fruit juices. In this study, the antioxidant activity of fruit juices was shown to be directly related to the content of ascorbic acid and total phenolics except in case of C. aurantium. The lower antioxidant activity of ripe fruit juices could be due to the possible reduction in the ascorbic acid and total phenolic content during ripening.