Identification and quantification of free, esterified, and insoluble-bound phenolics in grains of hulless barley varieties and their antioxidant activities

Abstract To study the phenolics in grains of hulless barley varieties harvested in the Qinghai-Tibet plateau region, free, esterified, and insoluble-bound phenolic fractions were extracted from grain of fourteen varieties. The phenolic components and antioxidant activity of the fractions were studied. Identification of phenolics profile in QB35 variety was studied using ultra-high-performance liquid chromatography-diode array with quadrupole time-of-flight and tandem mass spectrometry (UPLC-QTOF-MS/MS), which revealed fourteen phenolics in the free form, four in the esterified form, and seventeen in the insoluble-bound form. Total phenolic contents (TPC) of the fractions were tested finding significantly (p