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Mechanical Starch Damage Effects on Wheat Flour Tortilla Texture

¹Graduate research assistant, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ²Corresponding author. Phone: (215) 233-6489. E-mail: rflores@arserrc.gov ³Former associate professor, Department of Grain Science and Industry, Kansas State University, Manhattan, KS. Currently with USDA-ERRC Microbial Food Safety Research Unit, Wyndmoor, PA 19038.

To investigate the effects of mechanically damaged starch and flour particle size on the texture of fresh and stored flour tortillas, two commercial hard red winter wheat flour samples were reground four times using decreasing roll gaps. Tortillas were made with a modified hot-press procedure. Texture characteristics were measured after tortillas were stored 2 hr (fresh tortilla), 2 days, and 4 days. Damaged starch and particle size significantly affected (P < 0.05) flour water absorption, dough extensibility and resistance, and dough viscosity. As damaged starch increased and particle size decreased, the flour tortillas became less stretchable, the maximum force of Kramer shear decreased, and firmness and rollability increased. The effects of damaged starch and particle size on stretchability and Kramer shear were greater in fresh tortillas than in stored tortillas and became smaller as the storage time increased. However, the effects of damaged starch and particle size on rollability and firmness were smaller in fresh tortillas than in stored tortillas but became greater as the storage time increased.