Effects of processing on the phenolic contents, antioxidant activity and volatile profile of wheat bran tea

Wheat bran is a major milling by-product with significant nutritional importance. This study investigated the influence of processing on the antioxidant activity and volatile profile of wheat bran tea. The processing protocol involved two different pretreatments: soaking and cellulase treatment, followed by steaming and roasting. The results indicated that total phenolic content and antioxidant activity were reduced post both pretreatments, but increased after steaming, and dramatically increased after roasting. The cellulase-roasted samples had significantly higher antioxidant activity compared to soak-roasted samples. A total of forty key volatile compounds were identified in the wheat bran tea. The total volatile compounds were significantly increased by both soaking and cellulase treatments and steaming, but reduced by roasting. Compared to soaking pretreatment, cellulase pretreated samples had significantly higher total volatile compounds at each processing step. This study offers a practical method in processing of wheat bran into novel grain tea products.