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United States Department of Agriculture

Agricultural Research Service

Title: Detection of Wheat Field Sprouting Using a Pregelatinized Starch Substrate and Centrifugation

Authors
item Donelson, John - SWQL RETIRED
item Gaines, Charles
item Donelson, Thomas - SWQL
item Finney, Patrick

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2001
Publication Date: N/A

Interpretive Summary: When ripened wheat receives enough rain in the field before harvest, it will begin to sprout while still in the plant's head. This field sprouting is a serious negative quality attribute. The many wheat cultivars vary considerably in their resistance to field sprouting. Developed, but unreleased test lines of wheat should be screened for resistance to field sprouting and susceptible lines should be eliminated. Because a breeder or quality evaluator must screen many thousands of lines, a rapid and inexpensive screening test for field sprouting is needed. Such a screening test was developed and evaluated in this report. As sprouted grain has elevated activity of starch degrading enzymes, the test uses the activity of particularly one of those enzymes to degrade added pregelatinized starch, centrifuge the result and measure the activity of the enzyme as a function of the degree of field sprouting. The new test compared well with an older, more expensive to run, method. The new test has less error and was more sensitive at low levels of field sprouting. Wheat breeders and quality evaluators benefit from a new test that the operators estimate can evaluate more samples per hour for field sprouting susceptibility and is considerably more economical to run.

Technical Abstract: Wheat sprouting in the field before harvest is a serious negative quality attribute. Even low levels impact the economic value of the grain. Thus, unreleased test lines of wheat should be screened for resistance to field sprouting and susceptible lines should be eliminated. A new rapid and inexpensive screening test for field sprouting was developed, evaluated and compared with the established alpha-amylase activity (AAA) method, which is more expensive to perform and possibly slower for large numbers of samples. The new method uses the activity of sprout related elevation in alpha-amylase to partially degrade added pregelatinized starch. The hydrolytic products are centrifuged and the weight of the centrifugate is expressed as a percentage of the original weight of the added pregelatinized starch plus original meal or flour weight. The result is the alpha-amylase activity on pregelatinized starch (AAAPGS), a measure of the degree of field sprouting. The AAAPGS test had less error and was more sensitive at low levels of field sprouting than the AAA method. Grinders to produce wheat meal were compared for effect on AAAPGS and were compared to the AAA method. Flours produced slightly lower AAAPGS values than meals, but the replication errors of each were comparable. Coefficients of variation of the AAAPGS method were less than those of the AAA method. Wheat breeder's and quality evaluator's programs benefit from a more rapid and cheaper method that should evaluate more samples per hour for field sprouting susceptibility and should be more economical for large numbers of samples.

Last Modified: 12/21/2014
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