|Fleege, Lew - FORMERLY USDA-ARS-SWQL|
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 1997
Publication Date: N/A
Interpretive Summary: The main quality evaluation for soft wheat is test weight. It is widely accepted that test weight is often a poor predictor of milling and baking qualities. That is because test weight measurement is highly influenced by the conditions of shriveling and puffing of the kernels being measured. The affect of shriveling is generally a positive influence to those predictions. However, the affect of puffing is to confound the test weight prediction of end use qualities. A method was developed to distinguish between shriveling and puffing and to score the amount of each in a lot of wheat. That allows the distinction to be made between how much kernel shriveling is in a sample and how much puffing in involved. As independent measurements, puffing scores and shriveling scores were better predictors of several grain quality measurements than was test weight. These results allow valuable distinction to be made between when a wheat has low test weight because is simply puffed by rain and when it is genuinely low by detrimental shriveling. These results allow upward adjustment to be made to test weight values based on knowledge of the degree of puffing in a sample. The national and international grain trade can better predict milling properties and grain condition, by knowing how much shriveling and how much puffing is influencing the test weight prediction of grain quality.
Technical Abstract: Test weight is sometimes a poor predictor of the milling quality of soft wheats, particularly across several cultivars. Test weight is lowered by shriveled kernels, that have a detrimental influence on milling flour yield. Test weight is also lowered by kernels that are puffed due to rain/drying cycles, that usually have no negative influence on enduse quality, unless the grain is also field sprouted. A quality evaluation procedure was developed that distinguished between shriveling and puffing and produced a numeric score for each. Samples were aspirated to remove all shriveled kernels and evaluated before and after aspiration for test weight and Single Kernel Characterization System hardness index and kernel weight. In a sample of puffed grain, essentially all kernels are puffed. Therefore, puffing score was related to the test weight, hardness index, and density of aspirated samples. In a sample of shriveled grain there usually is a portion that is not shriveled. Therefore, shriveling score was related to the before and after change in test weight, kernel weight, and flour yield when samples were aspirated. Puffing and shriveling scores allow differentiation among several environmental influences on test weight variance. The results suggest possible upward adjustment to be made to test weight values based on the degree of innocuous puffing in a sample.