Effect of Polished-graded Flour Substitution to Commonly Milled Wheat Flour on the Properties of Dough and Bread

Abstract

The optimum conditions for breadmaking composed of various amounts of polished-graded flour and commonly milled soft-type wheat cultivar ‘Norm 61’ (N61) were studied. The viscoelastic properties of the doughs were also tested. When 30 or 50% of N61 was substituted with the 70-40% graded flour (Fraction B) of the whole wheat grain, the loaf volume and softness of bread crumbs increased with optimum amounts of water of 75 and 85%, respectively. Moreover, the addition of pentosanase (PEN) or cellulase (CEL) to the substituted N61 distinctly improved the loaf volume and retarded the retrogradation of bread crumbs as compared with those of N61 alone. Especially, the addition of PEN or CEL to the 50% graded-flour-substituted N61 having 85% water clearly increased viscoelastic parameters, such as the modulus of elasticity (y) and viscosity coefficient (v), as compared with those of N61 alone. In Farinograph data, 50% graded-flour-substituted N61 also decreased the arrival and development times, but increased the stability time. For the DSC result, 50% substitution tended to decrease gelatinization enthalpy with the addition of PEN or CEL. Microscopic observation of the 50% graded-flour-substituted N61 containing PEN showed that most of the starch granules were covered with extensible gluten and expanded still more during fermentation. In the case of the dough with the optimum water content, the gluten matrix was more fibrous and continuous, followed by sufficient gelatinization of starch granules as compared with N61 alone. Therefore, in the case of substituted N61 flour with graded flour, the optimum amount of water and hydrolysis of pentosan or cellulose in the endosperm and bran by PEN or CEL were needed to make good dough and baking properties.