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Effects of Varying Weight Ratios of Large and Small Wheat Starch Granules on Experimental Straight-Dough Bread¹

¹Cooperative investigations, United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and the Department of Grain Science and Industry, Kansas State University. Contribution No. 04-047-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66506. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Research chemist, USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. ³Supervisory research chemist, USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. ⁴Professors, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ⁵Corresponding author. Phone: 785-776-2703. Fax: 785-537-5534. E-mail: okchung@gmprc.ksu.edu

One commercial bread wheat flour with medium strength (11.3% protein content, 14% mb) was fractionated into starch, gluten, and water solubles by hand-washing. The starch fraction was separated further into large and small granules by repeated sedimentation. Large (10–40 μm diameter) and small (1–15 μm diameter) starch fractions were examined. Flour fractions were reconstituted to original levels in the flour using composites of varying weight percentages of starch granules: 0% small granules (100% large granules), 30, 60, and 100% (0% large granules). A modified straight-dough method was used in an experimental baking test. Crumb grain and texture were significantly affected. The bread made from the reconstituted flour with 30% small granules and 70% large granules starch had the highest crumb grain score (4.0, subjective method), the highest peak fineness value (1,029), and the second-highest elongation ratio (1.55). Inferior crumb grain scores and low fineness and elongation ratios were observed in breads made from flours with starch fractions with 100% small granules or 100% large granules. As the proportion of small granules increased in the reconstituted flour, it yielded bread with softer texture that was better maintained than the bread made from the reconstituted reference flour during storage.