Physicochemical Properties of Washed Wheat Bran

Wheat bran, a by-product of roller milling during the milling process of wheat, contained substantial amounts of residual starch that may interfere with the analysis of bran’s physicochemical properties. The main objectives of this study were to develop a method that removed away most of the starch adherent to milled wheat bran and to investigate the effects of washing on the physicochemical properties (such as water binding capacity) and composition (including insoluble dietary fiber, soluble dietary fiber, total dietary fiber) of washed and non-washed wheat bran. Soft white wheat bran was washed with distilled water at room temperature and mixed with a modified Servodyne mixer to wash residual starch away from bran. The bran-starch slurry was transferred into a SoyCow presser lined with a filter cloth and rinsed to remove as much starch as possible. The washed and non-washed bran samples were dried overnight at 60°C and ground to pass through 1000 or 425 µm screens. Washing was significantly reduced starch adherent to wheat bran by 76% (w/w), a changed the contents of insoluble dietary fiber and soluble dietary fiber from 39 to 69% (w/w) and from 4.93 to 1.68% (w/w), respectively. Water binding capacity was higher for washed bran and was not affected by bran particle size. The transition onset and peak temperatures of washed wheat bran samples were significantly higher than the counterpart values of non-washed bran samples. On the other hand, transition enthalpies of washed bran samples were lower than those of non-washed bran samples.