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Wheat Tortilla Quality: Impact of Amylose Content Adjustments Using Waxy Wheat Flour¹

¹A joint contribution of the University of Nebraska Agriculture Research Division and the United States Department of Agriculture, Agriculture Research Service as Journal Series Paper No. 13783. Mention of firm names or trade products does not imply that they are endorsed or recommended by the University of Nebraska or USDA over other firms or products not mentioned. ²Postdoctoral research associate and professor, respectively, Department of Food Science and Technology, University of Nebraska, Lincoln, NE 68583-0919. ³Corresponding author. E-mail: djackson1@unl.edu. Fax: 402-472-1693. ⁴USDA-ARS, 362C Plant Science Hall, University of Nebraska, Lincoln, NE 68583-0915. ⁵Professor, Department of Biometry, University of Nebraska, Lincoln, NE 68583-0712.

Amylose content is closely related to wheat flour pasting or thermal properties, and thus affects final food qualities. Fourteen flour blends with amylose content ranges of <1 to 29% were used to study tortilla production and quality parameters. Reduced amylose contents decreased dough stickiness and pliability; low amylose doughs were also very smooth in appearance. Very low flour amylose content was associated with earlier tortilla puffing and poor machinability during baking, darker color, low opacity, larger diameters, and reduced flexibility after storage. Tortilla texture analysis indicated that lowering amylose content gave fresh tortillas higher extensibility; after three or more days storage, however, low amylose flours required more force to break the tortillas and the rupture distances became shorter. These results, as reflected in covariate analysis, were not significantly affected by the flour blend's protein content, swelling volume/power, SDS-sedimentation volume, mixograph dough development time, or mixograph tolerance score. Based on our observation of an initial increase in extensibility with reduced-amylose tortillas, adding 10–20% waxy flour into wild-type flours should be ideal for restaurant (on-site) tortilla production or circumstances where tortillas are consumed shortly (within a day) after production. The optimal flour amylose content for hot-press wheat tortilla products is 24–26%.