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Effect of Physical State of Nonpolar Lipids on Rheology and Microstructure of Gluten-Starch and Wheat Flour Doughs

¹Department of Food Technology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden. ²Present address: Research Dept., Ajinomoto Frozen Foods, 1210-5 Oaza Yoshida, Oizumi-cho, Ora-gun, Gumma 370-0523, Japan. ³Corresponding author. E-mail: watanabea@ffa.ajinomoto.com

To clarify the effects of solid fat and liquid oil on dough in more detail in a simpler system, gluten-starch doughs with different gluten contents were investigated. The results from rheological measurements indicate that dough with a higher starch content has less resistance to strain and dough with a lower starch content has a rubber-like structure. The effects of the physical state of nonpolar lipids such as fat and oil on gluten-starch doughs and wheat flour doughs were investigated using rheological measurements and scanning electron microscopy. Fat-containing dough had more gas cells and a very smooth gluten gel surface with few holes, which may provide higher tolerance to strain. Moreover, the fat seemed to uniformly distribute the gluten gel between the starch granules in the dough, which reduced the friction between starch granules and led to a lower storage modulus. A mechanism governing the effect of fats on loaf volume is proposed based on the phenomena observed in the fat-containing dough.