Midge damage (MDGE DMG)

Description

Midge damage is defined in the Official Grain Grading Guide.

For grading purposes, midge damaged kernels must have at least two of the following characteristics;

• A rupture of the bran on either the back or side of the kernel
• A distinct white line or mark, located on the back or side of the kernel
• The kernel is distinctly distorted

Procedure for assessment

Midge damage is an objective grading factor.

To assess midge damaged samples, the inspector performs a physical separation to assess the percentage of these damaged kernels in the sample. The number of grams utilized to perform the assessment is predetermined and defined in the Official Grain Grading Guide. The inspector will then apply the tolerances for midge and sawfly as set out in the Grade Determinant Tables found in the Official Grain Grading Guide.

Photographs

Midge damage - Canada Western Red Spring wheat

• A distinct white mark, located on the back of the kernel
• The kernel is distinctly distorted

Midge damage (CWRS)

• A distinct white mark, located on the back of the kernel
• The kernel is distinctly distorted

Midge and severely sprouted damage (CWRS)

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted
• Sprout (coleoptile) is evidence of germination
• Sprout (coleoptile) is broken - the kernel is considered severely sprouted
• This kernel is considered both midge damaged and and severely sprouted in the assessment process

Midge damage and sprout damage (CWRS)

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted
• Sprout (coleoptile) is evidence of germination
• Sprout does not extend beyond the normal contour of the germ
• This kernel is considered both midge damaged and and sprouted in the assessment process

Midge damage (CWRS)

• A rupture of the bran on the side of the kernel
• A distinct white line located on the side of the kernel

Midge damage (CWRS)

• A rupture of the bran on the back of the kernel
• A distinct white line located on the back of the kernel

Midge damage - Canada Western Amber Durum wheat

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted

Midge damage (CWAD)

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted

Midge damage (CWAD)

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted

Midge damage (CWAD)

• A rupture of the bran on the back of the kernel
• The kernel is distinctly distorted

Cause

The Orange blossom wheat midge (Sitodiplosis mosellana) (Government of Alberta, Alberta Agriculture, Food and Rural Development) causes midge-damaged kernels. This pest is found in wheat-growing areas of Europe, Asia and North America. The orange fly deposits its eggs on the floret and then the hatching larvae feed on the developing grain.

End-use issues

The shrunken distorted grains reduce flour yields and produce dark flours with increased flour ash. Seriously midge-damaged wheat exhibits weak, sticky dough properties; low baking absorption and poor bread quality. Protein content is abnormally high, but gluten protein quality is distinctly inferior.

Midge damage has a serious effect on durum wheat semolina milling performance. As midge damage increases, semolina refinement (ash content, color and speck count) declines and pasta can became less bright and undesirably brown.

More information on the affects of midge damage on processing is available in Grain Research Laboratory papers on factors affecting processing performance of common wheat.

Self assessment

Review the following pictures and identify which kernels you would consider midge damaged. Continue scrolling down to find the answers.

Answers