Effects of dietary fiber on structure formation in bread during baking process

The link between the intake of dietary fiber (DF) and health benefits has prompted the interest in fiberenriched foods such as fiber-enriched baked goods. A distinction is established between insoluble DF and soluble DF. Insoluble and soluble forms of DF have different compositions resulting in different of nutritional, physiological and technological properties. In this work, the effect of insoluble and soluble fraction of different dietary fiber (coffee silverskin and inulin) on dough rheological behavior, leavening and baking performance was studied. Dough prepared from wheat flour containing two type of fibers were submitted to a lubricated squeezing test and to dynamic oscillatory measurements. Bubble evolution during leavening and baking phases was studied by measuring the variation in time of the total volume of the sample by means of Image Analysis. A dough without fiber was used as a control. Experimental evidence of the different behaviour of the dough and bread obtained with fibers are presented and discussed. It was proved that DF incorporation into wheat dough greatly interferes with protein association and its further aggregation during heating. In general, the addition of insoluble fibers causes the dough’s strength to increase. A negative effect of fibers on leavening and baking is observed. The experimental evidence suggests that the functional role of fibers in bubble evolution depend on DF type. Results from macrostructure analysis agree with those of rheological measurements.