Whole-wheat flour particle size influences dough properties, bread structure and in vitro starch digestibility
Whole-wheat flour (WWF) is increasingly popular because of the healthy benefits of whole grains. This study investigated the effect of WWF particle size on dough property, bread quality and in vitro starch digestibility. The WWF was made from intact whole grain directly. Three WWF particle sizes were examined, including coarse, medium and fine with mean size at 1315, 450 and 199 µm, respectively. The dough made from WWF of larger particle size exhibited lower extensibility and stability, and subsequently the bread had more compact structure (i.e. lower open porosity and thicker cell thickness), smaller specific volume and harder texture, which were regarded as poor quality attributes. On the other hand, the bread made from the fine WWF exhibited higher amount of released glucose than those made from the coarse and medium WWFs. Moreover, the particle size of bread bolus showed no significant effect on in vitro starch digestion. The whole study demonstrated that the particle size of WWF plays a critical element in determining both bread quality and digestibility.