Author
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Hareland, Gary |
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Submitted to: National Association of Wheat Growers Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/10/2000 Publication Date: 3/10/2000 Citation: Hareland, G.A. 2000. Improving flour quality of preharvest sprouted spring wheat by pearling. In: Proceedings of the 3rd Annual National Wheat Industry Research Forum, Las Vegas, N.V. p.56. Interpretive Summary: Preharvest sprouted wheat that contains high alpha-amylase enzyme activity causes unfavorable dough handling properties and inferior bread quality. The level of alpha-amylase in a kernel of wheat depends upon the severity of sprouting, which is caused by excessive moisture or damp conditions in the field prior to harvest. Attempts were made to decrease alpha-amylase activity in flour of preharvest sprouted wheat by pearling the kernels before milling, thereby increasing the value of the flour for baking purposes. Alpha-amylase activity in flour was related to both the severity of preharvest sprouting in the wheat and to pearling time. Pearling preharvest sprouted wheat before milling tended to improve the overall quality of flour. Pearling caused substantial increases in flour viscosity of some preharvested sprouted wheat, reduced flour ash content, affected the physical properties of the dough, and improved the overall quality of the bread. Technical Abstract: Attempts were made to decrease alpha-amylase activity in flour of preharvest sprouted wheat by pearling the kernels before milling, thereby increasing the value of flour for baking purposes. Four sample lots of preharvest sprouted HRS wheat and one control sample of sound wheat were used. Alpha-amylase was measured by the Hagberg falling number (FN) method. Average FN values of the five sample lots were 62, 92, 163, 187, and 425 sec. Sub-samples of each lot were pearled in a laboratory pearler for 0.5, 1, and 2 min to remove bran layers. For comparison, replicated sub-samples of each lot were not pearled. Pearled and non-pearled samples (800 g) were tempered to 14.5% moisture basis and milled in a Buhler experimental mill. Flour was tested for FN and RVA viscosity. Physical dough properties were measured using the Farinograph and Alveograph. Bread baking quality was compared using a straight dough baking procedure. Flour from wheat with FN of 62 sec did not increase in FN regardless of pearling time. Flour from wheat with FN of 92 sec showed an increase in FN to 173 sec with no pearling and 260 sec with pearling time of 2 min. Flour from wheat with FN values of 163 sec and 187 sec showed significant increases in FN to 300 sec or more when pearled. Flour from sound wheat with FN of 425 sec showed no significant increase in FN with pearling. Pearling preharvest sprouted wheat before milling improved the overall quality of flour, with the exception of the wheat sample with a FN of 62 sec. Flour ash content decreased as pearling time increased. Farinogram and water absorption were not affected by pearling, but P/L ratios from alveograph tests and RVA viscosity increased as pearling time increased. Bread quality was significantly improved by pearling. |
