Corn - Chapter 17 | Official Grain Grading Guide

Grading factors

Blue-eye mould

Blue-eye mould

Germs of kernels appear dark blue with mould, or there may be just a visible mouldy blue streak under the hull of the germ. In the second case, peel back the hull from the germ to examine the germ.

Blue-eye mould is included in the tolerance for Damage.

Caramelized kernels

Caramelized kernels

Caramelized kernels are kernels that were very immature when dried at a high temperature in a dryer, and the heat has turned the kernel to a scorched colour similar to that of heated kernels. The outer hull of the kernel may be peeled off showing a slightly damaged kernel inside. These kernels are classed as Damaged.

Classes

Classes

Corn is classed as yellow, white, or mixed. The class forms part of the grade name; for example, Corn, Sample CW Yellow Account Heated.

Samples of yellow and white corn containing less than 95.0% of one class are designated Mixed; for example, Corn No. 1 CE Mixed.

Contaminated grain

Contaminated grain

Important:

Wear gloves and a mask to handle any sample that is suspected of containing contaminated grain.

Contaminated is defined in the “Canada Grain Act” as; “Contaminated means, in respect of grain, containing any substance in sufficient quantity that the grain is unfit for consumption by persons or animals or is adulterated within the meaning of the regulations made pursuant to sections B.01.046(1), B.15.001 and B.15.002(1) of the Food and Drugs Act.”

Samples deemed to be contaminated by the Grain Research Laboratory in consultation with the Chief Grain Inspector for Canada are graded Corn, Sample Condemned.

Cracked corn and foreign material (CCFM)

Cracked corn and foreign material (CCFM)

Cracked corn and foreign material includes any of the following:

  • All material including kernels and pieces of kernels of corn or any other grains which pass through a No. 12 round-hole sieve or, for samples with a moisture level over 25.0%, through the No. 14 round-hole sieve
  • All foreign material other than stones handpicked from the sample, including pieces of cobs that were not removed by sieving

Procedures

Important:

Follow procedures for assessing dockage.

Note:

Because breakage occurs during handling at terminal elevators, round down percentages by weight of CCFM to the nearest whole number on all officially sampled and inspected domestic or export shipments from a terminal elevator.

For example, a sample containing 4.7% CCFM by weight is recorded as containing 4.0% CCFM for grading purposes only on officially sampled and inspected shipments from terminal elevator.

Damage (DMG)

Damage (DMG)

Damaged kernels include whole kernels or pieces of kernels which are

  • Affected by blue-eye mould and other types of moulds
  • Sprouted
  • Ground-damaged
  • Weathered
  • Diseased
  • Frosted
  • Scorched, from a drier
  • Heated, naturally, or from a drier, or caramelized
  • Rotted
Earth pellets

Earth pellets

  • Hard earth pellets are pellets that do not crumble under light pressure. See Stones.
  • Soft earth pellets are pellets that crumble under light pressure. See Cracked corn and foreign material.
Excreta (EXCR)

Excreta (EXCR)

Excrement from any animal including mammals, birds and insects.

Important:

Wear gloves and a mask to handle any samples that you suspect may contain excreta.

Fertilizer pellets (FERT PLTS)

Fertilizer pellets (FERT PLTS)

Fertilizer pellets are a manufactured plant nutrient product used by producers in the production of grain. They are typically small, round or irregular shaped and usually white, grey, brown, pink or reddish in colour.

Note:

Canadian Grain Commission personnel should refer to ISO national work instruction “Suspect Contaminated Grain, Handling Procedures” for procedures to be followed when handling samples containing fertilizer pellets.

Procedures

  • Handpick any fertilizer pellets and determine the concentration basis the net working sample.
  • Fertilizer pellets are assessed as stones when the concentration does not exceed 1.0% of the net sample weight.
  • Samples containing fertilizer pellets in excess of 1.0% of the net sample weight are graded Corn, Held IP Suspect Contaminated Grain.
Fireburnt (FBNT)

Fireburnt (FBNT)

Fireburnt kernels are kernels charred or scorched by fire. A cross-section of a fireburnt kernel resembles charcoal with numerous air holes. The air holes result in a low weight kernel which crumbles easily under pressure.

Procedures

Samples of corn containing fireburnt kernels are graded Corn, Sample CW/CE (class) Account /Fireburnt.

Foreign material (FM)

Foreign material (FM)

See Cracked corn and foreign material (CCFM).

Heated (HTD)

Heated (HTD)

Heated kernels have at least one of the following characteristics:

  • Whole kernels or pieces of kernels which range in colour from amber to dark brown over the entire kernel
  • Kernels which are totally discoloured by fermentation and show no natural colour on the crowns or dorsals, or both
  • The germ of the kernel is amber to dark brown and is severely puffed in the germ area when heated in a drier
  • Heated seeds of other grains are included in the tolerance for Heated.

If kernels exhibit none of the above characteristics, but are not whole or sound, they are classed as Damaged.

Note:

Cracked corn and foreign material that is heated is included with heated corn for grade assessment.

Odour (ODOR)

Odour (ODOR)

There is no numeric tolerance for odour. Consider

  • The basic quality of the sample
  • The type and degree of the odour
  • The presence of visible residue causing the odour

Grains grading No. 1 through 4 must be cool and sweet. Corn grading No. 5 may have a slight odour associated with the low quality, but the odour cannot be sour or musty.

Heated, fireburnt and odour for corn.
If odour is the grade determinant and there is . . . Then the grade is . . .
An excessive objectionable odour not associated with the quality of the grain, but not heated or fireburnt Corn, Sample CW/CE Account Odour 
An excessive heated odour Corn, Sample CW/CE Account Heated 
An excessive fireburnt odour Corn, Sample CW/CE Account  Fireburnt 
Rotted (ROT)

Rotted (ROT)

Rotted kernels are whole kernels or pieces of kernels which are visibly in advanced stages of decomposition and feel spongy under pressure. Rotted kernels are included in the percentage of heated kernels for grade assessment.

Stones (STNS)

Stones (STNS)

Stones are hard shale, coal, hard earth pellets, and any other non toxic materials of similar consistency. Fertilizer pellets are assessed as stones when constituting 1.0% or less of the net sample weight. (See Fertilizer pellets for specific procedures to be followed when samples contain fertilizer pellets.)

Procedures

  1. Handpick stones from a representative portion of the cleaned sample.
  2. Determine stone concentration in the net sample.
  • In western Canada samples of grain containing stones in excess of “basic grade” tolerances, up to 2.5% are graded Corn, Rejected “basic grade” Account Stones. The “basic grade” refers to a grade established in the Canada Grain Regulations (grades listed in the first column in grade determinant tables) that would have been assigned to the sample if it contained no stones.
  • In eastern Canada samples of grain containing stones in excess of grade tolerances are degraded to lower grades. Samples containing stones in excess of the tolerance of the lowest grade established by regulation up to 2.5% are graded Corn, Sample CE (class) Account Stones.
  • In western and eastern Canada grain containing more than 2.5% stones is graded Corn, Sample Salvage.

Examples: Western Canada

Excerpt from grade determinant tables for Corn, Canada Western, White, Yellow or Mixed
Grade name Stones %
No. 1 CW 0.15
No. 2 CW 0.15
No. 3 CW 0.15
No. 4 CW 0.15
No. 5 CW 0.15

Basic grade:....................... Corn, No. 2 CW Yellow

Reason for basic grade:...... 3.0% Cracked corn and foreign material

Grade in Western Canada if stones found.
If the above sample contained Grade in Western Canada
0.5% stones Corn, Rejected No. 2 CW Yellow Account Stones
3.0% stones Corn, Sample Salvage

Examples: Eastern Canada

Excerpt from grade determinants table for Corn, Canada Eastern, White, Yellow or Mixed
Grade name Stones %
No. 1 CE 0.15
No. 2 CE 0.15
No. 3 CE 0.15
No. 4 CE 0.15
No. 5 CE 0.15

Basic grade:....................... Corn, No. 2 CE Yellow

Reason for basic grade:...... 3.0% Cracked corn and foreign material

Grade in Eastern Canada if stones found.
If the above sample contained Grade in Eastern Canada
0.5% stones Corn, Sample CE Yellow Account Stones
3.0% stones Corn, Sample Salvage
Treated seed and other chemical substances

Treated seed and other chemical substances

Treated seed

Treated seed is grain that has been coated with an agricultural chemical for agronomic purposes. These seed dressings contain a dye to render the treated seed visually conspicuous. The colour of the dye varies depending upon the type of treatment and the type of grain. The current Canadian colour standards for pesticide seed treatments are: cereals–pink or red,  canola–baby blue or green. Seed treated with an inoculant may have a green stain. The coatings or stains may appear greasy or powdery and surface area distribution ranges from tiny flecks to complete coverage.

Other chemical substances

Other chemical substances refers to any chemical residues either adhering to the kernel or remaining in the sample and to samples having a chemical odour of any kind.

Important:

Wear gloves and a mask to handle any samples that you suspect may contain contaminated grain.

If a sample is suspected of being coated with a pesticide, desiccant, inoculant or if the sample contains evidence of any foreign chemical substance other than fertilizer pellets, the sample shall be graded Corn, Held IP Suspect Contaminated Grain.

Note:

Canadian Grain Commission personnel should refer to ISO national work instruction “Suspect Contaminated Grain, Handling Procedures” for specific procedures to be followed when handling samples suspected of containing treated seed or other chemical substances.

Varieties

Varieties

Corn is graded without reference to variety.