Smudge Damage (SM)

Description

Smudge is a discolouration on the kernel and is an objective grading factor. The discolouration may be brown, black or red.

The discolouration is assessed as smudge in amber durum if:

  1. More than one-half the kernel is discoloured, or
  2. Discolouration of the crease
    • Has spread onto the cheeks of the kernel regardless of any discolouration of the germ
    • Appears as a thin line extending more than half the length of the crease, in combination with any discolouration of the germ.

Photographs

kernels with no smudge, smudge and red smudge
Each column, in the above image, represents one kernel viewed from three angles.
kernels with germ and crease
  • Discolouration of the crease appears as a thin line extending more than half the length of the crease, in combination with any discolouration of the germ
  • Considered as Smudge
kernels with discolouration on germ and kernels with discolouration at crease
  • Discolouration of the crease appears as a thin line extending more than half the length of the crease, in combination with any discolouration of the germ
  • Considered as Smudge
kernels with discolouration on germ and kernels with discolouration at crease and cheeks
  • Discolouration of the crease has spread onto the cheeks of the kernel regardless of any discolouration of the germ
  • Considered as Smudge

Cause

The discolouration is as a result of infection by some common field fungi such as Alternaria alternata.

End-use issues

Surface discoloration due to fungi such as A. alternata is not a safety concern. However, it is considered a serious quality defect in durum wheat because it causes dark specks in semolina, which is used to make pasta (Dexter and Matsuo 1982; Dexter 1993).

Related links

  • Factors affecting processing. The implications of frequently encountered grading factors on the processing quality of durum wheat, by J.E. Dexter and N.M. Edwards, 1998.
  • Factors affecting processing performance. The implications of frequently encountered grading factors on the processing quality of common wheat, by J.E. Dexter and N.M. Edwards, 1997.
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