| Relationships among grain hardness, pentosan fractions and end-use quality of wheat. Cereal Chemistry 77:241-247 |
Bettge,A.D. and Morris,C.F.
USDA-ARS Western Wheat Quality Lab |
| Grain texture ("hardness") in wheat
(Triticum aestivum L.) is a major determinant of end-usage. Variation
in grain texture can be conceptually assigned to the two major hardness classes,
which result from the action of one major gene (Hardness), or to as yet undetermined
factors contributing to residual variation within hardness classes. Identifying
the physical-chemical basis of both sources of texture variation could provide
a means of better controlling or manipulating this quality trait. Pursuant to
this objective, the role of pentosans was examined. Pentosan fractions (membrane-associated,
total and soluble) were isolated from13 hard and 13 soft wheat samples and their
flours. Among the hard wheat samples, pentosans had a minimal role in modifying
grain hardness. However, among the soft wheat samples, pentosans appeared to
have a significant hardness-modifying effect that carried over into end-use
quality. Among the soft wheat samples, pentosan fractions, along with wheat
protein, accounted for 53 to 76% of the variation in grain texture, depending
on the method used to quantify texture. Membrane-associated pentosans were the
most influential single parameter in modeling grain texture for the soft wheat
samples. Membrane-associated pentosans were most influential in accounting for
variation (69%) in Alkaline Water Retention Capacity. Total pentosans together
with flour protein accounted for 87% of the variation in cookie diameter among
the soft wheat samples, with the total pentosan fraction being the more influential.
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