Effects of different processing methods on the nutrition content of dietary fiber powder made from purple wheat bran

Wheat bran is the by-product of flour processing. Despite being nutritious, it is unsuitable for direct use in human consumption because of its palatability. It used to serve as animal feed. The study is aimed to use two wheat bran processing methods for producing the fine powder production which could be more conveniently used as the nutritious food with good palatability or as commercial fiber supplement product. The method I organically combined the sequential steps of crushing, puffing and milling of the wheat bran to produce the dietary fiber powder. Method II and method I are the same in the processing steps, but distinct in maintained humidity of the bran, processing speeds and temperature of both extruder screw and grinder. The chemical analyses indicated that the ratio of soluble dietary fiber of the dietary fiber powder made via method I increased significantly compared to the raw wheat bran and the dietary fiber powder made via method II. The results also showed that method I was superior to method II in facilitating the increment of the nutrition content, especially in the content of protein, trace elements and minerals. The processed 120–130 mesh purple wheat bran powder is more delicate and tasty.