Backgrounder: Research summary for severely sprouted grading factor in wheat

The Canadian Grain Commission’s Grain Research Laboratory and Industry Services teams conducted research from 2022 to 2023 to better understand the impact of severely sprouted kernels on the end-use functionality of western wheats.

Dr. Bin Xiao Fu, Program Manager of the Bread Wheat and Durum program, and his team compared severely sprouted kernels to regular sprouted kernels, specifically reviewing kernels that met the severely sprouted definition in the Official Grain Grading Guide of “the sprout has been clearly broken and only a portion remains”. Kernels that meet this definition have a broken or missing sprout that’s lacking clear evidence of the sprout’s length or severity.

Difference between sprouted and severely sprouted grading factors

Sprouted and severely sprouted are grading factors for western wheat classes. Sprouted kernels mean that the kernel is germinating, which accelerates the production of alpha-amylase. This has negative impacts on the wheat’s Falling Number, which is an internationally accepted indicator of alpha-amylase activity and soundness of the grain.

The sprouted grading factor includes wheat kernels that have sprouts within the contours of the germ. Severely sprouted wheat kernels have sprouts that extend beyond the contours of the germ.

Sprout within the contour
Sprout within the contour
Sprout extended beyond the contour
Sprout extended beyond the contour

Research process

Grain inspectors at the Canadian Grain Commission sorted the sprouted seeds into 5 categories from collected cargo loading samples of Canada Western Red Spring (CWRS) and Canada Western Amber Durum (CWAD):

  1. Sprouted clearly beyond the contour (severely sprouted)
  2. Severely degenerated (severely sprouted)
  3. Sprout broken or missing with evidence (severely sprouted)
  4. Sprout broken or missing without clear evidence (severely sprouted)
  5. Regular sprouted

Each of these categories was evaluated for alpha-amylase activity and their impact on Falling Number.

Research results

Overall, the Grain Research Laboratory found the following in their research:

  • Categories 1 through 3 (severely sprouted) showed higher levels of alpha-amylase activity and more detrimental impact on Falling Number
  • Category 4 (severely sprouted) had similar alpha-amylase activity and impact on Falling Number as Category 5 (regular sprouted) kernels

Category 4 was previous considered severely sprouted in the Official Grain Grading Guide, but its impact on end-use functionality was similar to that of regular sprouted kernels. As a result, the severely sprouted grading factor for western wheat has been modified to remove this portion of the definition.

Graphs and tables for alpha-amylase activity and impact on Falling Number

CWRS single seed alpha-amylase results
  CWRS severely sprouted and sprouted category
1 2 3 4 5
Lowest activity* 0.79 0.24 0.96 <0.01 0.01
Highest activity* 5.89 3.72 7.06 1.80 1.61
Average activity* 2.27 1.92 2.35 0.75 0.56
Standard deviation 1.23 0.87 1.26 0.53 0.35
Number of seeds 30 30 29 30 30
* Amylase SD units/30 mg seed
CWAD single seed alpha-amylase results
  CWAD severely sprouted and sprouted category
1 2 3 4 5
Lowest activity* 0.64 0.10 0.19 <0.01 0.20
Highest activity* 22.72 3.82 3.97 4.11 1.59
Average activity* 2.50 1.46 1.73 0.94 0.88
Standard deviation 3.89 0.92 0.78 0.88 0.33
Number of seeds 30 30 30 30 30
* Amylase SD units/40 mg seed
Impact of severely sprouted and sprouted on Falling Number of a base CWRS wheat
Impact of severely sprouted and sprouted on Falling Number of a base CWRS wheat
Details
Category - CWRS 0.1% 0.2% 0.3% 0.5%
Base 414 ± 5 414 ± 5 414 ± 5 414 ± 5
1 357 ± 14 345 ± 18 314 ± 16 263 ± 2
2 314 ± 4 339 ± 8 307 ± 27 239 ± 4
3 348 ± 35 314 ± 28 270 ± 13 242 ± 6
4 398 ± 10 380 ± 3 356 ± 3 333 ± 22
5 407 ± 2 420 ± 22 391 ± 2 379 ± 5
Impact of severely sprouted on Falling Number of a base CWAD wheat
Impact of severely sprouted on Falling Number of a base CWAD wheat
Details
Category - CWAD 0.2% 0.4% 0.6% 1.2%
Base 467 ± 1 467 ± 1 467 ± 1 467 ± 1
1 390 ± 1 361 ± 2 339 ± 5 292 ± 6
2 424 ± 6 396 ± 13 361 ± 8 311 ± 16
3 389 ± 14 384 ± 9 347 ± 5 295 ± 6
4 405 ± 7 404 ± 1 375 ± 2 364 ± 12
5 411 ± 32 407 ± 17 400 ± 19 375 ± 7
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