What are Hard Vitreous Kernels?
Canadian wheat is known for being a high-quality and premium wheat in the global marketplace. To maintain this reputation, high grading standards are set by the Canadian Grain Commission (CGC) to ensure quality meets end-users’ needs.
In 2025, downgrading due to hard vitreous kernel (HVK) levels was one of the main factors affecting Canada Western Red Spring (CWRS) wheat, according to the CGC’s harvest sample program and the Cereals Canada 2025 New Wheat Crop Report Webinar. This blog post will provide an overview of HVKs and related grading thresholds.
What are HVKs and what is the downgrading threshold?
- Vitreousness is used to describe the natural translucent colouring of hard wheat and is an indicator of kernel hardness.
- It is described as a “glassy” appearance. HVKs are wheat kernels that have this translucent colouring.
- HVKs are a grading factor for CWRS and Canadian Western Amber Durum (CWAD) wheats, but the grading factors differ between the two wheat classes.
Table 1. Canadian Grain Commission HVK grading thresholds.1
Wheat Class | Grade | Minimum HVK (%) |
CWRS | No. 1 | 65 |
| No. 2, 3 & feed | No minimum |
CWAD | No. 1 | 80 |
| No. 2 | 60 |
| No. 3 | 40 |
| No. 4 & 5 | No minimum |
Why is it important?
CWAD
- In the CWAD class, there is a strong relationship between semolina extraction and high HVKs.
- High extraction levels are important to millers and why CWAD has stricter HVK requirements than the CWRS class.
CWRS
- HVK influences milling quality for CWRS wheat, but not to the same extent as with CWAD wheat.
- For example, Cereals Canada states “a very low level of HVK could result in the production of more break flour and less purifiable endosperm during milling.”
- Furthermore, high levels of HVKs are currently an important visual factor for some end-uses and is information some major importers require.