Corn: Grading

Important definitions

Net weight of sample
The sample after cleaning and removal of dockage is referred to as the cleaned sample. Its weight is the net weight of the sample. Percentages by weight for grading refer to percentages of the net weight.
Hazardous substances in samples
Wear gloves and a mask to handle any samples that you suspect may contain hazardous substances. Hazardous substances are defined in the Regulations as “any pesticide, herbicide, desiccant or inoculant.”
Non-registered varieties
Where grain of any kind is not a registered variety under the Seeds Act, no person shall, except with the permission of the Canadian Grain Commission, assign a statutory grade to that grain which is higher than the lowest grade established by regulation for that kind of grain. An order is issued annually to allow non-registered varieties of Corn to be graded higher than the lowest statutory grade.

Representative portions for grading

All grading is done on representative portions divided down from the clean sample, using a Boerner-type divider.

The terms “Minimum” and “Maximum” refer to the range of sample portion size to be analyzed when an objective factor is present. The optimum representative portion (see glossary) is determined by taking into consideration the tolerance and concentration of the objective factor being assessed.

Representative portion of corn for grading, grams
Grading factor Sample portion size range
Minimum Maximum
Caramelized kernels 100 250
Classes 100 working sample
Cracked corn and foreign material working sample working sample
Damage 100 250
Excreta working sample working sample
Fertilizer pellets working sample working sample
Fireburnt working sample working sample
Heated and rotted 100 working sample
Odour working sample working sample
Stones working sample working sample
Treated seed working sample working sample
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