Fig. 23: Kernel visual distinguishability. Each class of wheat grown in western Canada has a distinct kernel size, shape and colour to permit efficient visual segregation. Classes from left to right: Canada Western Red Spring, Canada Western Red Winter, Canada Western Extra Strong, Canada Prairie Spring Red, Canada Prairie Spring White, Canada Western Soft White Spring and Canada Western Amber Durum
A specific kernel size, shape and colour is reserved for each wheat class grown in western Canada (Fig. 23). A requirement for registering a wheat variety in western Canada is that it must have the visual appearance reserved for the class for which it qualifies. This unique feature of the Canadian wheat grading and classification system is referred to as kernel visual distinguishability (KVD). KVD ensures that wheat classes are easily and cost effectively kept distinct throughout the handling system. This preserves the unique attributes of each class; admixing of classes results in a product with less processing value. In eastern Canada, KVD is a requirement only for registration into the Canada Eastern White Winter (CEWW) wheat class.

Physical condition is a primary determinant of wheat processing value. Physical condition is determined primarily by growing conditions. In Canada, wheat is graded according to grade standards established by the CGC (2003a). The grade standards are set to mitigate differences in quality year-to-year. The amount
of wheat grading into the top grades will be less in years when growing conditions are not ideal, but the quality of a given class and grade must be comparable to previous years (Preston et al., 1988).

Grade definitions are established under the authority of the Canada Grain Regulations with direction from the CGC. Tables of specifications provide structure for assigning grades to grains. Specifications include factors such as minimum test weight, and maximum tolerances for factors such as foreign material, contrasting wheat classes, damaged kernels and broken kernels. There are two sets of standards: primary and export. Primary standards are used to grade wheat upon delivery into grain facilities, including export terminals. Prior to arrival at terminals, the grading is done by private grain handling companies. Wheat arriving at terminals is graded by the CGC. The grade assigned to a lot by the CGC is the basis for payment.

Export standards are used to grade wheat destined for export. The CGC is solely responsible for grading of export cargoes from terminal facilities. Some factors such as foreign material and contrasting classes have stricter tolerances in export standards than for primary standards. Important export grade standards for Canada Western Red Spring (CWRS) wheat and Canada Western Amber Durum (CWAD) wheat, the two largest classes of wheat grown in Canada, are shown in Tab. 17 and Tab. 18. All CGC primary and export standards, definitions of various types of damage, and methodologies employed by CGC inspectors may be found in the Official Grain Grading Guide (CGC, 2003a) which is available on the CGC website at
Tab. 17 : Tolerances for some Canada Western Red Spring wheat export grade determinantsa
Tab. 18: Tolerances for some Canada Western Amber Durum wheat export grade determinantsa
Associated with each wheat grade, there is also a specification for degree of soundness. For example, degree of soundness for No 1 CWRS is defined as "reasonably well matured, reasonably free from damaged kernels", for No 2 CWRS it is defined as "fairly well matured, may be moderately bleached or frost-damaged, reasonably free from severely damaged kernels" and for No 3 CWRS it is defined as "may be frost-damaged, immature or weather-damaged, moderately free from severely damaged kernels". These definitions relate to factors such as frost damage, mildew and degree of maturity which are difficult to measure objectively. Standard samples are prepared as visual aids in accessing degree of soundness. The standard samples are prepared by the CGC every autumn, following the harvest, to reflect the visual appearance associated with growing conditions from the most recent harvest. The CGC submits the standard samples for approval to the Western and Eastern Grain Standards Committees, which are composed of producers, exporters, processors and scientific and technical specialists. Once approved they are distributed to CGC offices, and to inspection offices of private grain companies.

An important feature of the grading standards for all western Canadian wheat classes, and for CEWW in eastern Canada, is variety designation. This relates to the strict variety registration process in Canada, which will be discussed in more detail later. The only varieties eligible for the milling grades of Canadian wheat classes with variety designation are those with processing quality proven to conform to the quality model established for the class. The CGC designates which varieties are eligible for each class of wheat. Variety designation assures that intrinsic quality is the same for all grades within a given class. Processing quality differences between milling grades then are solely attributable to grade tolerances, and differences in protein content.

The Canadian wheat grading system has a scientific substructure. The Grain Research Laboratory (GRL), the scientific branch of CGC, and Industry Services, the branch of CGC responsible for setting grade standards, investigate the effects on end-use quality of the grading factors encountered in Canada so that grade tolerances can be realistically set (Dexter and Edwards, 1998a, 1998b).

The combination of a strict wheat variety registration requirement, and a grading system with a scientific basis, provide a direct linkage between the visual appearance and the processing quality of Canadian wheat classes with variety designation. That linkage, together with KVD, allows the segregation of Canadian wheat quickly and efficiently according to processing potential.

Throughout loading from a terminal elevator, the CGC continuously samples and grades the wheat, and officially weighs it. The CGC has a strict loading protocol that must be followed. At all times wheat must remain within the export standards established for the grade ordered. When the wheat has been loaded, the CGC issues a Certificate Final certifying the grade and exact weight of the shipment. The Certificate Final is the customer's guarantee that if there is a disagreement concerning quantity or quality of a shipment, the CGC will investigate.

Post a Comment

Previous Post Next Post