Q-TOF LC/MS identification and UHPLC-Online ABTS antioxidant activity guided mapping of barley polyphenols

•Polyphenol content of eight Australian-grown barley varieties were characterised.•Antioxidant activity of polyphenols was identified using UHPLC-online ABTS system.•Phenolic composition and antioxidant activity exhibited significant variation.•Variety Hindmarsh had higher polyphenolic content and antioxidant activity.•Prodelphinidin B3 had the highest abundance and antioxidant activity. The polyphenol composition and antioxidant activity of seven Australian-grown barley varieties were characterized in this study. UHPLC with an online ABTS system was used to identify individual polyphenols while simultaneously measuring their antioxidant activity. The Q-TOF LC/MS system was utilized to identify the phenolic compounds that demonstrated substantial antioxidant activity. The variety, Hindmarsh, showed the highest total phenolic content and antioxidant activity. There was no significant difference observed amongst the other varieties in their total phenolic content, however, they did have significant variation in proanthocyanidin content and antioxidant activity (p