Effect of boiling and roasting on phenolic components and their bioaccessibilities of highland barley

This study investigated the effects of two thermal treatments (boiling and roasting) on highland barley (HB) phenolics and their bioaccessibilities (in-vitro). The UPLC Q-TOF-MS system was utilized to identify the individual phenolic compounds in HB. Twenty-one phenolics and two non-phenolic compounds were identified in HB, and the fundamental phenolics in HB were flavanols and phenolic acids. Both boiling and roasting improved free and bound phenolics' extractability and antioxidant activity by loosening the grain matrix. In-vitro simulated digestion showed that thermal-treated HB had higher bioaccessibility of phenolics than raw samples, and the boiled samples had higher bioaccessibility (36.3%) of phenolics than those of roasted samples (22.75%). Therefore, boiling and roasting could be used as non-chemical treatments to improve whole grain's phenolic content and their bioaccessibility.