Grain grading factors measured objectivity

by Teresa Acklin
Share This:

Wheat may be damaged by the effects of fungal diseases such as fusarium head blight (FHB) and ergot. Kernel quality is degraded by the presence of tombstone kernels, shriveled, shrunken or blackened kernels. Kernel yield is reduced and FHB may produce toxins in the grain, which must be determined using DON analysis.

Environmental conditions dictate the severity of damage but variety, location and handling are also important factors in fungal infestation. FHB affects not only wheat but barley, corn, rye and oats. In recent years the loss of revenue due to contaminated material has exceeded hundreds of millions of dollars across North America.

Black tip or black point (germ end) and smudge (crease and sides) are also caused by fungal infection. Darkened and discolored areas caused by disease degrade the visual appearance of the grain. This in turn affects the milling and processing quality by reducing flour or semolina yield, lowering product brightness and increasing the amount of dark specks. Again, environmental conditions, variety susceptibility, crop location and handling are factors in the growth and spread of disease.

Damage caused by disease is graded according to standards determined by governmental agencies. Grade factors vary considerably among commodities and between countries. The one common denominator across all boundaries is the producers' and processors' reliance on subjective assessment of grade factors that determines the value or price of the product.

It has been noted that grain inspection could be enhanced by using automated equipment for specific parameters. Grade factors that can be easily identified and rapidly evaluated would save time and resources, leaving problematic inspection to the expertly trained grader. Using instruments that mimic human vision, dark and discolored surface areas and kernel size and shape can be rapidly measured.

With the advance of objective analytical methods, grain grading can be standardized among individuals and between facilities on various types of grain and seeds. Using established digital image analysis technology, the SPY system uses a CCD array and cold cathode illumination for the acquisition of grain images. After the image is collected, the SPY software identifies and quantifies each kernel according to the grade parameter selected.

Results are reported in graphical and table format, which can be saved to spreadsheets or databases. Data can be compiled from year to year, allowing production to be tracked by grain variety and growing location. Image archiving is optional and can be used for reference or for standardizing grade techniques.

Grade factors such as damaged and discolored (DnD) areas on the kernel surface can also be measured using the SPY. The amount of darkened surface area is measured and reported on a per kernel basis rather than on a per batch basis. Fusarium-damaged kernels (FDK) are measured based on comparison to normal kernels. Tombstone kernels are identified as well as ergot kernels. The SPY provides a rapid screening tool for quantifying fungal-damaged whole kernels.

Grains and seeds of all types have specific physical sizes and shapes (morphology), which are based on genotype and affected by environmental conditions. The size and shape uniformity of wheat is desirable due to its effect on milling and flour yield — the more uniform the kernel, the greater the yield. Plus, kernel uniformity can lower production costs and ensure more consistent end products.

In breeding programs, morphological attributes can demonstrate whether trait enhancement was achieved and may be important in the selection of breeding lines. On a per kernel basis, the SPY measures a range of morphological features, such as area, length, width, perimeter, aspect and diameter.

Non-grade factors, such as moisture, content and dockage, also can be measured.

As contract growing increases, objective quality assessment becomes essential. Premiums are paid on products that meet or exceed the contract requirements.

In-house quality standards are often the key to market share. Measurements can be customized for specific features and objective assessment can be guaranteed through the use of opto-electronics and computing.


Contributed by suppliers, technical profiles feature new technology, products, specific applications or proprietary concepts. This article was contributed by Kate Harrigan, director of sales and business development at Maztech MicroVision Ltd., Ottawa, Ontario, Canada.