Composition and distribution of phenolic acids in Ponkan (Citrus poonensis Hort. ex Tanaka) and Huyou (Citrus paradisi Macf. Changshanhuyou) during maturity

Composition and distribution of phenolic acids in Ponkan (Citrus poonensis Hort. ex Tanaka) and Huyou (Citrus paradisi Macf. Changshanhuyou) during maturity was investigated comprehensively in this study. High-performance liquid chromatography (HPLC) coupled with photodiode array (PDA) detector method was developed to separate and quantify protocatechuic, p-hydroxybenzoic, vanillic, caffeic, p-coumaric, ferulic, sinapic, and chlorogenic. For all of the phenolic acids, detection limits were about 0.01 μg/mL. Repeatability was 0.57–2.99% (relative standard deviation, RSD) for intraday and recovery ranged from 80.23% to 114.53%. In this study, phenolic acids were divided into four fractions: free, ester, glycoside and ester-bound. Generally, in each fraction, Ponkan had higher content of phenolic acids than Huyou, and with maturity there was a sharp decrease of them in both varieties, also peel contained more of them than flesh. Furthermore, chlorogenic acid and ferulic acid were the highest among the eight quantified phenolic acids, and content of caffeic acid was rather high at unripe stage, and hydroxycinnamic acids accounted for a larger portion compared with hydroxybenzoic acids especially for Ponkan. The total content of phenolic acids ranged from 180 μg/g DW (flesh of Huyou at ripe stage) to 5060 μg/g DW (peel of Ponkan at unripe stage). The data obtained here can be potentially used for discriminating the adulteration of citrus juices and may be useful for consumers and food technologists.