A Study on Flavonoid Compounds of Six Citrus Varieties during Maturity and Ripening Stages

In addition to physical and chemical properties of citrus fruit, its quality depends on antioxidant compounds such as ascorbic acid, phenols, flavonoids and antioxidant enzymes. Flavonoids group, especially flavonoid glycosides are dominant in citrus, which prevent chronic diseases such as cancer and cardiovascular diseases. In this experiment, the total flavonoids, naringin, hesperidin, neohesperidin, quercetin and catechin were measured in the mature and ripe fruits of six citrus varieties (Thomson, Siavaraz, Moro, Sanguinello, Tarocco and Page) by HPLC analysis. The results showed that all cultivars had high level of total flavonoid at the ripening stage. The amount of naringin was highest in 'Thomson' and 'Tarocco' (with 452.8 and 824.8 μgg-1 respectively) at maturity phase. Hesperidin accumulation was higher in blood oranges than blond varieties. The Sanguinello and Siavaraz had the highest value of neohesperidin especially in ripe fruits. The pulp of Tarocco had the highest level of catechin with 24.36 μgg-1 followed by Siavaraz with 10.6 μgg-1 at ripening stage. The Quercetin levels were higher in immature fruits selected from Thomson, Siavaraz and Tarocco varieties. Among the studied varieties, 'Tarocco' variety showed higher levels of flavonoid compounds at the ripened or mature stage.