Effect of enzymes on the dough properties and bread quality of wheat flour partly substituted for amaranth flour

The commercial hard wheat flour, “Cameria” replaced by amaranth flour (∼20%), was tested for its dough properties and baking qualities including sensory evaluation. The loaf volumes of bread baked with 5%, 10% and 20% of amaranth flour substitution were 94%, 89% and 83%, respectively, of the control (wheat only). Additions of lipase (2,250 units/kg of flour) and hemicellulase (1×104 units/kg of flour) to the 10%-amaranth flour-substituted wheat flour increased the loaf volumes about 18% and 23%, respectively, over the control. The firmness of bread-crumbs baked from 10%-amaranth flour-substituted wheat flour added with lipase, hemicellulase, or both of them after storage for three days became significantly softer than that of the control. Farinograph data showed the increase of water absorption, arrival time and weakness in proportion to the increase of amaranth flour substitution. Viscoelastic parameters of dough, such as modulus of elasticity and viscosity coefficient increased in proportion to the increase of amaranth flour substituted for wheat flour. Pasting properties of starch prepared from 10%-amaranth flour-substituted wheat dough with the addition of lipase, hemicellulase or both decreased setback and peak viscosity. Amaranth flour contained a higher amount of alkaline-insoluble protein than wheat flour. Sensory test of 10%-amaranth flour-substituted wheat bread did not show significant improvement compared to the control. However, the bread baked with lipase was preferred by most of the panel members to the control, except for its color.