Exploitation of bran from sprouted wheat: effect on dough rheology and bread-making performance

Bread is consumed daily by the majority of the population, and for years the food industry has focused on increasing the nutritional value of this product by adding bran as vehicle for bio-compounds, including fibre. However, enhancing the dietary fibre of bread is challenging from both a technological and sensorial standpoint. In the past few years, several pre-treatments have been proposed to modify bran and limit its negative effects on dough properties and bread volume. The best results were obtained when enzymatic treatments and/or fermentation were applied. In this study, the endogenous enzymatic activities developed during wheat germination (or sprouting) have been exploited as an alternative biotechnological approach. To do this, wheat kernels were sprouted under controlled conditions and the related bran (B_GERM) was added to flour at 20% level. The effect of B_GERM-enrichment on dough rheological properties and bread-making performance was assessed. Bran from untreated wheat was used as reference (B_CTRL). Unlike B_CTRL, B_GERM-enrichment positively affected the gluten aggregation profile (as evaluated by GlutoPeak test), showing a curve similar to that of a strong wheat flour. When B_GERM was added to flour, dough water absorption and its stability significantly decreased, this is likely related to proteolytic activity. As for leavening properties, B_GERM improved dough leavening by decreasing the proofing time from 161 min to 131 min (for B_CTRL and B_GERM, respectively), probably due to simple sugar production during sprouting. On the other hand, gas production and dough development were not significantly affected by biotechnology treatment. Compared to B_CTRL, B_GERM improved specific volume and crumb softness of the bread, even during storage (up to three days). In conclusion, bran from sprouted wheat could be an interesting ingredient for producing fiber-enriched bread.