Distribution of Bound Hydroxycinnamic Acids and Their Glycosyl Esters in Barley (Hordeum vulgare L.) Air-Classified Flour: Comparative Study between Reversed Phase-High Performance Chromatography-Mass Spectrometry (RP-HPLC/MS) and Spectrophotometric

摘要

The level of bound hydroxycinnamic acid was determined by spectrophotometry (as total hydroxycinnamic compounds and free-radical-scavenging activity) and reversed-phase high-performance chromatography (RP-HPLC) coupled to mass spectrometry (MS) in barley flours (whole meals and air-classified fractions: coarse fraction and fine fraction). Hydroxycinnamic acids and their derivatives were the main bound phenols in barley flours. A total of 12 different hydroxycinnamic acids were identified and quantified by HPLC/diode array detector (DAD)-MS within 90 min. Ferulic acid (as a simple and glycosylated derivative) was the main phenolic acid in barley flours, representing 89-93% of total hydroxycinnamic acids. The amount of total hydroxycinnamic acid in air-classified coarse fraction was 2 and 3 times higher than those of whole meal and the air-classified fine fraction, respectively. Similarly, the coarse fraction showed higher antioxidant activity (650.03 μmol of TEAC/ 100 g of flour) compared to whole meal and the fine fraction (388.78 and 320.27μmol of TEAC/100 g of flour, respectively).