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United States Department of Agriculture

Agricultural Research Service

Title: Prediction of Test Weight from a Small Volume Specific Gravity Measurement

Authors
item Donelson, J - USDA ARS SWQL, RETIRED
item Gaines, Charles
item Andrews, Lonnie
item Finney, Patrick

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2001
Publication Date: N/A

Interpretive Summary: The density of wheat is used as a measure of commercial value and in part, determines the price paid to the seller. Such density (weight per fixed volume) measurements do not work well for small sample lots of 20 to 50 grams. A method was studied that uses the specific gravity (volume per fixed weight) of wheat samples of only 20 and 40 grams. A good relationship existed between the density and the specific gravity of the samples and an equation was developed to change specific gravity values into bulk density (test weight) values. Where sample sizes are too small for reliable bulk density measurements, this method allows the prediction of bulk density (test weight) values from specific gravity observations. That will be very useful for the wheat breeder or quality evaluator who often does not have sample sizes large enough for direct test weight evaluation.

Technical Abstract: The specific gravity (cc/g) of small (20g and 40g) samples of soft wheats from three states were rapidly measured and compared to bulk density (g/cc) measurements (micro test weights). Specific gravities were correlated with test weights for both cleaned and uncleaned samples. The relationship between specific gravity and test weight was linear unless the samples were severely shriveled. Operator effect was not statistically significant. Simple linear regression analysis produced equations that predicted with high R-square values micro test weights from specific gravity measurements. Both 20g and 40g sample sizes were satisfactory, however 40g samples produced better statistical relationships.

Last Modified: 8/22/2014
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