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Effect of Physical States of Nonpolar Lipids on Rheology, Ultracentrifugation, and Microstructure of Wheat Flour Dough

¹Food Research & Development Labs, Ajinomoto Co., Suzuki-cho Kawasaki-ku Kawasaki 210-8681 Japan. ²Present address: Research Dept. Ajinomoto Frozen Food Co., 1210-5 Oaza Yoshida Oizumi-cho, Ora-gun Gunma 370-0523 Japan. ³Corresponding author. E-mail: watanabea@ffa.ajinomoto.com. ⁴Ajinomoto Oil Mills Co., 7-41 Daikoku-cho Tsurumi-ku, Yokohama 230-0053 Japan. ⁵Department of Food Technology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.

In the previous study, we investigated effect of physical state of nonpolar lipids of gluten-starch model dough. This experiment examined a real wheat flour dough system to assess the role of fat crystals in the breadmaking processes. These experiments were performed with a baking test and an investigation of wheat flour dough through rheological measurements (both large and small deformations), scanning electron microscopy, and ultracentrifugation. As a result, we found that the added oil was absorbed in the gluten structure, causing the aggregation of the gluten, which gave rise to more elastic behavior. In contrast, solid fat seemed to be distributed uniformly between the starch granules in the dough, reducing the friction between the starch granules and facilitating thin gluten gel layers. These properties lead to the lower G′ value and the increased viscous behavior, which yields an increase in loaf volume. In addition, the supposed mechanism behind the large loaf volume described in the previous study was that fat provides a uniform distribution of the dough components, and that the dough can thus expand easily, resulting in a larger loaf volume, which was supported in the wheat flour dough system. In conclusion, we found that thin, expandable gluten films and the uniform dispersion of gluten and starch granules in the dough are prerequisites for attaining better baking performance.