Effects of superfine grinding of bran on the properties of dough and qualities of steamed bread

In order to investigate the influence of superfine grinding of wheat bran on the qualities of southern and northern-styles steamed bread, wheat bran with different particle size (coarse, medium and superfine grinding) was blended with low/medium protein content flours. For the two kinds of wheat flours, their water absorption, peak viscosity, starch hot-gel stability and starch crystallinity significantly (P < 0.05) increased with the reduction of bran particle size investigated by Mixolab, while dough development time decreased. The results of Rheofermentometer F4 showed that superfine grinding of bran resulted in lower maximum height and total CO2 production of dough during fermentation compared to coarse and medium wheat bran. The Chinese southern and northern-styles steamed bread making test showed that reducing the bran particle size could significantly (P < 0.05) decrease the specific volume of steamed bread. Higher crumb hardness and starch relative crystallinity after 24 h storage were observed in steamed bread of superfine bran than those of coarse or medium wheat bran. These results demonstrated that the superfine grinding of wheat bran (from ∼433 μm to ∼39 μm) could have detrimental effect on the quality of steamed bread.