Identifying and assaying the quantity of flavonoid compounds in some citrus biotypes

The natural biotypes in the germplasm collection of the Citrus and Subtropical Fruits Research Center are a valuable genetic resource in the country that may not be suitable for fresh eating but they can be used in processing industry. Therefore, the fruits of 16 biotypes, coded as 6, 8, 15, 21, 24, 25, 26, 29, 30, 41, 43, 45, 48, 51, 52 and 53, were harvested at two stages, 60 days after 50% of flowering (after June drop) and 120 days after 50% of flowering (beginning of physiological maturity). Some variables were measured such as total phenol and antioxidant capacity, and flavonoid compounds including hesperidin, naringin, quercetin and catechin content. Results showed that the maximum amount of catechin and quersetin was observed at 60 days after 50% of flowering in the biotype 29. The. amount of Hesperidin and Naringin was significantly different between biotypes. The highest amount of hesperidin and naringin was observed in biotypes 43 and 41 at 120 days after flowering, respectively. Generally, antioxidant capacity was reduced during of growth whereas biotypes 6, 29, 43, and 51 had the highest antioxidant capacity at 60 days after flowering. The highest total phenol content was observed at maturity stage of fruits. Biotype 48 showed higher amount of total phenol as compared with other biotypes. Totally, biotypes 29, 41, and 43 have high potential of flavonoid compounds to be used in the genetic improvement programs of cultivar and rootstock, food processing and pharmaceutical industry.