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Estimating Chalkiness in Endosperm of Typical and Bleached Durum Kernels from Transmission Scanned Images

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Applied Engineering in Agriculture. 38(4): 651-658. (doi: 10.13031/aea.15023) @2022
Authors:   Daniel L. Brabec, Lester O. Pordesimo
Keywords:   Grain inspection, HVAC (hard and vitreous kernels of amber color), Image analysis, Vitreousness.


Durum wheat kernels were examined using flatbed scanner in transmission mode.

Image processing routines were written to determine the %chalkiness per kernel.

The distribution of %chalkiness uniquely described market samples.

Abstract. The vitreousness of durum samples is regarded by the worldwide wheat industry as an important quality factor for durum shipments. One issue with grading durum occurs on occasional years of unfavorable harvest conditions which result in the kernel outer bran becoming cloudy. Imaging scanners can use either reflective or transmitted lighting. All scanned images of our durum samples were collected using transmissive lighting. Although, “vitreousness” is the usual term applied to durum samples, for this study, “chalkiness” or the inverse property was featured.

Both typical and bleached durum kernels were imaged and analyzed. Bleaching seeds has aided grain inspector to visually evaluate the kernels. With computer imaging analysis of bleached kernels, the magnitude of %chalk was significantly attenuated with bleaching verses typical kernels. Still, discrimination of medium and highly chalky kernels was possible with both the typical and bleached seeds.

Seed orientation was a source of measurement variability. Seeds were manually and carefully oriented into two distinctly different positions. At the critical lower levels of detection, crease-down orientation may indicate a 100% vitreous seed with the two-dimension view of the scanner, but then 11 of 25 seeds measured some amount of chalkiness when the seed was turned on its side. Furthermore, for seeds with higher amounts of chalkiness, over half of those seeds measured 30% differences.

Several durum market samples were provided by Federal Grain Inspection Service and contained levels of non-vitreous seeds for each of three sub-classes of durum: 80%, 65%, 50% vitreous seed. The samples were imaged and analyzed, and chalkiness distributions were plotted. These plots characterize the %chalk for the three classes of wheat. The imaging methods worked satisfactorily for the high and medium levels %chalk per kernel. But the very-low level of chalkiness per kernel proved to be more challenging and was not consistent.

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