Abstract: Phenolic acid, known as a kind of multipurpose bioactive compound, widely spreads throughout the plant kingdom. Citrus fruits may be the important resource of dietary phenolic acids. Eight phenolic acids in Satsuma mandarin during maturity were determined by high-performance liquid chromatography (HPLC) coupled with photodiode array (PDA) detector in this study, which were:protocatechuic, p-hydroxybenzoic, vanillic, caffeic, p-coumaric, ferulic, sinapic and chlorogenic. In this study phenolic acids were divided into four fractions:free, ester, glycoside and ester-bound. As a result, contents of phenolic acids in flesh decreased with maturity, while that in peel had the highest content at half ripe stage, and contents of phenolic acids in peel were much higher than that in flesh. Furthermore, there were more hydroxycinnamics than hydroxybenzoics both in peel and flesh, and contents of chlorogenic acid and ferulic acid were highest among the eight quantified phenolic acids. The data on composition and distribution of phenolic acid in citrus fruits can be potentially used for discriminating the adulteration of citrus juices;also they may be useful for food technologists and consumers. In addition, research on flavonoids and phenolic acids of citrus fruits and their antioxidant properties may also be valuable in selecting citrus varieties with high quality directed to reducing the risk of cardiovascular and other disease. The application prospect of composition and distribution of phenolic acids in citrus fruits are exciting.

Key words: Satsuma mandarin, phenolic acid, HPLC, composition, maturity