Effect of water content and flour particle size on gluten-free bread quality and digestibility

The impact of dough hydration level and particle size distribution of the rice flour on the gluten free bread quality and in vitro starch hydrolysis was studied. Rice flour was fractionated in fine and coarse parts and mixed with different amounts of water (70%, 90% and 110% hydration levels) and the rest of ingredients used for making gluten free bread. A larger bread specific volume was obtained when coarser fraction and great dough hydration (90-110%) were combined. The crumb texture improved when increasing dough hydration, although that effect was more pronounced when breads were obtained from a fine fraction. The estimated glycaemic index was higher in breads with higher hydration (90-110%). Slowly digestible starch (SDS) and resistant starch (RS) increased in the coarse flour breads. The coarse fraction complemented with a great dough hydration (90-110%) was the most suitable combination for developing rice bread when considering the bread volume and crumb texture. However, the lowest dough hydration limited starch gelatinization and hindered the in vitro starch digestibility.