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ARS Home » Plains Area » Manhattan, Kansas » Center for Grain and Animal Health Research » Grain Quality and Structure Research » Research » Publications at this Location » Publication #155500
Title: SIZE DISTRIBUTION AND PROPERTIES OF WHEAT STARCH GRANULES IN RELATION TO CRUMB GRAIN SCORE OF PUP-LOAF BREAD

Author
item PARK, SEOK-HO - KANSAS STATE UNIV
item Chung, Okkyung
item SEIB, PAUL - KANSAS STATE UNIV

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2004
Publication Date: 11/1/2004
Citation: Park, S., Chung, O.K., Seib, P.A. 2004. Size distribution and properties of wheat starch granules in relation to crumb grain score of pup-loaf bread. Cereal Chemistry. Vol 81 (6): 699-704.

Interpretive Summary: Wheat starch granules are generally composed of large A-granules (>10 m diameter) and small B-granules (<10 m diameter), which have different physical, chemical, and functional properties. During the baking process, starch goes through physical changes that could affect bread quality parameters such as loaf volume and crumb grain. Most prior work on the role of starch in breadmaking has focused on loaf volume or staling and did not consider crumb grain. Bread with small, elongated, and lacy crumb grain is considered desirable. We tested 12 hard winter wheat flours to find relationships between their starch properties and crumb grain structure. Starches were isolated by a dough hand-washing method. Prime starch was fractionated further into A-granules and B-granules by repeated sedimentation in an aqueous slurry. We found that as the mean A-granule size increased in a flour, the crumb grain improved. In addition, the weight percentage of B-granules seemed to have optimum range (19.8 to 22.5%) for the best crumb grain structure. This work will lead to a better understanding of the factors controlling crumb grain and help improve U.S. wheat quality.

Technical Abstract: Twelve hard winter wheat flours with protein contents of 11.8-13.6% (14% mb) were selected to investigate starch properties associated with the crumb grain score of experimentally baked pup-loaf bread. The 12 flours were classified in four groups depending on the crumb grain scores which ranged from 1 (questionable-unsatisfactory) to 4 (satisfactory). Flours in groups 1, 2, 3, and 4 produced breads with pup-loaf volumes ranging from 910 to 1035, 1000 to 1005, 950 to 1025, and 955 to 1010 cm3, respectively. Starches were isolated by a dough hand-washing method and purified by washing to give 75-79% combined yield (dry flour basis) of prime (62-71%) and tailing (7-16%) starches. The prime starch was fractionated further into large A-granules and small B-granules by repeated sedimentation in aqueous slurry. All starches were assayed for weight percentage (wt%) of B-granules, swelling power (92.5oC), amylose content, and granular size distribution by quantitative digital image analysis. A positive linear correlation was found between the crumb grain scores and the A-granule sizes (r = 0.65, P<0.05), and a polynomial relationship (r = 0.67, P<0.05) occurred between the score and the wt% of B-granule starch. The best crumb grain score was obtained when a flour had a wt% of B-granules from 19.8 to 22.5%, shown by varietal effects.