The standards for mustard quality are set by the Canadian Grain Commission. The same primary and export grade determinants are used for all three mustard types. The only exception is that there is no inconspicuous admixture percentage for yellow mustard like there is for brown and oriental mustards. Inconspicuous admixture includes any seeds such as canola, common wild mustard seed or any other seeds that blend with oriental or brown mustard and cannot be readily identified. In the table below, the term “Other Classes” refers to the presence of other types of mustard or Brassica carinata in the sample that are not the mustard type being graded. Total damage is the maximum per cent of damaged seed allowed and includes seeds that are distinctly shriveled, badly discoloured from mould, completely and densely covered with rime or dried white mucilage, are excessively weathered, sprouted, distinctly green, heated or otherwise damaged.
| Grade Name | Standard of Quality | Damage (%) | ||||||||
| Degree of Soundness | Other Classes (%) | Distinctly Green | Heated | Total | ||||||
| No. 1 Canada | Reasonably well-matured, sweet, good natural colour | 0.5 | 1.5 | 0.1 | 1.5 | |||||
| No. 2 Canada | Fairly well-matured, sweet, reasonably good colour | 2 | 2 | 0.2 | 3 | |||||
| No. 3 Canada | May have the natural odour associated with low quality seed, not any odour that would indicate serious deterioration | 5 | 3.5 | 0.5 | 5 | |||||
| No. 4 Canada | May have the natural odour associated with low quality seed, not any odour that would indicate serious deterioration | 10 | 3.5 | 1 | 10 | |||||
| Grade Name | Inconspicuous admixture ** (%) | Conspicuous inseparable seeds | Other (%) | |||||||
| Distinctly detrimental (%) | Total (%) | |||||||||
| Cow cockle | Sclerotinia | Wild mustard Canola / rapeseed | Total distinctly detrimental | Ergot | Excreta* | Soft earth pellets | Stones | |||
| No. 1 Canada | 1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.3 | 0.05 | 1K | 0.01 | 0.05 |
| No. 2 Canada | 1 | 0.2 | 0.2 | 0.2 | 0.2 | 0.5 | 0.05 | 1K | 0.2 | 0.05 |
| No. 3 Canada | 1 | 0.3 | 0.3 | 0.3 | 0.3 | 0.7 | 0.05 | 1K | 0.3 | 0.05 |
| No. 4 Canada | 1 | 1 | 1 | 1 | 1 | 3 | 0.05 | 0.005 | 1 | 0.1 |
* Number of kernel-sized pieces in 500 g
** Not a grading factor for yellow mustard
Source: Canadian Grain Commission
Green seed
Green seeds are immature seed that contain the pigment chlorophyll which can give an off-colour to finished products. Under adequate environmental conditions, chlorophyll will be converted to other compounds by three enzymes as part of the natural maturing process, and thus lose the green colour associated with the chlorophyll. The required enzymes are only active when seed moisture is greater than 20 per cent and if the ambient temperature is above 5˚C. As a result, frost prior to harvest or severe heat after swathing will destroy those enzymes, causing the green colour to be locked in the seed, since under those circumstances the chlorophyll will not be degraded as it would with the normal maturation process. Green seed will only diminish in the plant when the enzymes are active; it will not be further reduced in the bin if those enzymes are no longer active.
Heated seed
Heating of the grain may be caused by excessive moisture and/or high temperature during storage. Due to the higher oil content, mustard must be stored at a lower per cent moisture than cereals. The moisture will be concentrated in the meal portion of the seed making overall moisture levels appear low, but it is important to remember that all of the moisture will be concentrated in half of the seed. Mustard stored long-term should be at less than nine per cent moisture and less than 20˚C to prevent heating. The moisture levels of the grain will increase by approximately one per cent when first placed in the bin due to a sweating period caused by respiration of the seed.
Sclerotinia sclerotia
Sclerotinia sclerotiorum causes disease in mustard, canola, sunflower, flax, pulse crops and many broadleaf weed species. The disease-causing fungus produces hard black resting bodies (sclerotia) in or on the stems of infected plants. During harvest, the sclerotia can be threshed out and end up in the seed. Downgrading will occur even when low levels of infestation are present.
Ergot
Ergot is a disease of cereals and grasses that will not infect mustard or other broadleaf crops. The fungus that causes ergot also produces sclerotia similar to sclerotinia. There is a low tolerance for ergot in grain because the sclerotia contain a mycotoxin.
Ergot infestation of mustard grain can occur if there are infected cereal volunteers or weeds in the crop or contaminated harvesting and transportation equipment or storage facilities.
Excreta
Excreta are the droppings of rodents and insects, and contamination is often due to unclean harvest, storage or transportation equipment. Inadequate facilities will allow access to rodents and result in excreta contamination. Good quality mustard has no tolerance for excreta.
Rime
Yellow mustard has a mucilage that surrounds the seed coat that has desirable water binding properties. With repeated wetting and drying of the seed, the mucilage will flake off and the seed will be covered in a white substance known as rime. Though rime is not graded by the Canadian Grain Commission, it is a downgrading factor for yellow mustard at the buyer and processor level.
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