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Effect of Outer Bran Layers from Germinated Wheat Grains on Breadmaking Properties

¹Faculty of Home Economics, Laboratory of Food Technology, Kobe Women's University, Suma-Ku, Kobe City, 654-8585, Japan. ²Corresponding author. E-mail: seguchi@suma.kobe-wu.ac.jp ³Nagata Sangyo, 215 Senbonya, Yamasaki-cho, Shiso-city, Hyogo, 671-1219, Japan. ⁴Nippon Flour Mills, 5-1-3 Midorigaoka Atsugi, Kanagawa, 243-0041, Japan.

Wheat grains were germinated in the dark at room temperature (24°C) for 1, 2, 3, 5, and 8 days. Germinated wheat grains were pearled in a Waring blender, and the outer bran layers were separated from the pearled grains. Breadmaking was performed with wheat flour and 10% of the outer bran layer. Breadmaking properties (bread height [mm] and specific volume [cm³/g]) were gradually enhanced by blending the germinated outer bran layers, and maximum specific volume was obtained after 5 days of germination. However, the improvement was lost after 8 days of germination. Rapid ViscoAnalyser (RVA) and Brabender Farinograph profiles of wheat flour and outer bran layers (10%) indicated that the maximum decrease of peak viscosity and increase of angle of tail were obtained after 3 and 5 days of germination, respectively. Those changes are presumed to be due to the action of enzymes found in the outer bran layers. Activities of α- and β-amylase, lipase, protease, and xylanase in the outer bran layers were measured, and correlation coefficients (r) between breadmaking properties and peak viscosity (RVA), angle of tail (farinograph), and enzyme activities were calculated. These data suggest that xylanase and α-amylase activities in the outer bran layers were highly related to the enhancement of the breadmaking properties.