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Lecture 6

Lecture 6. Physical Properties of Grains Grading of Wheat. Gramineae (Poaceae) Grass Family. 600 genera, 10,000 species Most common plant family Food plants, ornamentals, forage crops, weeds, and even building materials

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Lecture 6

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  1. Lecture 6 Physical Properties of Grains Grading of Wheat

  2. Gramineae (Poaceae)Grass Family • 600 genera, 10,000 species • Most common plant family • Food plants, ornamentals, forage crops, weeds, and even building materials • Fruit is called a caryopsis: a dry, single-seeded, indehiscent fruit in which the seed and pericarp are fused

  3. Geometrical Properties • How do the following properties we talked about on Tuesday related to official grading? • Shape • Size • Volume • Sphericity • Surface Area

  4. Class Differences

  5. Class Differences

  6. Class Differences

  7. Class Differences

  8. Class Differences

  9. Definitions in Wheat • Dockage: material removed by an approved device according to procedures prescribed by FGIS typically including weed seeds, weed stems, straw, grain other than wheat, sand, dirt, dust • Shrunken and broken: pass through a 0.064 x 3/8” slotted sieve • Foreign Material: insect parts, small seeds, stones, and pieces of stems or cobs • Damaged Kernels: remaining broken pieces, or whole kernels that are weather damaged, diseased, frost damaged, germ damaged, heat damaged, insect bored, mold damaged, sprout damaged, or otherwise materially damaged • Total defects: sum of shrunken & broken, foreign material, and damaged kernels

  10. Wheat Grading Steps • Get a 1000 to 1025 g representative sample • Examine for heating, odor, filth, castor beans, crotalaria seeds, garlic, glass, insect infestation, and unknown substances • Divide out a 250g (representative portion) and determine moisture content, return • Determine % dockage from whole sample

  11. Wheat Grading Steps 5. Examine the dockage-free sample for ergot, smut, stones, treated seeds, and odor 6. Determine the test weight per bushel of the dockage-free sample 7. When necessary, divide out a representative portion and determine the % protein 8. Divide out a representative portion (250 g) and determine the % shrunken and broken kernels

  12. Wheat Grading Steps 9. If necessary, divide out representative samples from the SHBN-free sample and pick percentage of kernel damage (15 g) and foreign material (30 g). Damage may include contrasting wheat classes, damaged kernels, and heat-damaged kernels.

  13. Harvesting machinery Age, condition, and adjustments Weeds in the field Cropping system Environmental conditions Handling of the material Sources of Dockage

  14. Where would you take a representative sample?

  15. Types of Wheat Kernel Damage

  16. Kernel Damage

  17. Kernel Damage

  18. Kernel Damage

  19. Kernel Damage

  20. NOT Kernel Damage

  21. Kernel Damage

  22. Kernel Damage

  23. Special Grades

  24. Special Grades

  25. Conclusions • Dockage is not an official U.S. grading factor but can be specified in a contract • Dockage is actually added to wheat during blending to “just meet” the grade requirements!

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