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Corn Harvest Quality Report 2019/2020

Contents

  1. Export Cargo Quality Highlights
  2. Introduction
  3. Grade Factors
  4. Quality Test Results
  5. Moisture
  6. Chemical Composition
  7. Physical Factors
  8. Stress Cracks
  9. 100- Kernel Weight
  10. Kernel Volume
  11. Kernel True Density
  12. Whole Kernels
  13. Horneous (Hard) Endosperm
  14. Mycotoxins
  15. Assessing the Presence of Aflatoxins and Deoxynivalenol (DON)
  16. Background: Mycotoxins General
  17. Background: Aflatoxins
  18. Background: Deoxynivalenol (DON) or Vomitoxin
  19. Background: Fumonisin
  20. U.S. Corn Export System
  21. Planting and Early Growth Conditions
  22. Pollination and Grain-fill Conditions
  23. Harvest Conditions
  24. Comparison of 2019 to 2018, 2017 and the 5YA
  25. U.S. Corn Production, Usage & Outlook
  26. U.S. Corn Use and Ending Stocks
  27. Survey Design and Sampling
  28. Statistical Analysis
  29. Grade Factors
  30. Physical Factors
  31. Mycotoxins
  32. U.S. Corn Grades & Conversions

Physical Factors

Physical factors are other quality attributes that are neither grade factors nor chemical composition. Physical factors include stress cracks, kernel weight, kernel volume, true density, percent whole kernels and percent horneous (hard) endosperm. Tests for these physical factors provide additional information about the processing characteristics of corn for various uses, as well as corn’s storability and potential for breakage in handling. The physical composition of the corn kernel influences the quality attributes; which is, in turn, affected by genetics and growing and handling conditions.
Corn kernels are made up of four parts: the germ or embryo, the tip cap, the pericarp or outer covering and the endosperm. The endosperm represents about 82% of the kernel and consists of soft (also referred to as floury or opaque) endosperm and of horneous (also called hard or vitreous) endosperm, as shown above. The endosperm contains primarily starch and protein, the germ contains oil and some protein, and the pericarp and tip cap are mostly fiber.

Summary: Physical Factors

  • Average U.S. Aggregate stress cracks (9%) was higher than 2018, 2017 and 5YA (all 5%), indicating susceptibility to breakage in 2019 may be higher than 2018, 2017 and the 5YA.
  • Among the ECAs, the Gulf, Pacific Northwest and Southern Rail ECA had stress crack averages of 10, 9 and 6%, respectively. The Southern Rail has had the lowest stress crack averages in 2019, 2018, 2017 and 5YA among all ECAs.
  • Average U.S. Aggregate 100-k weight in 2019 (34.60 g) was lower than 2018 (35.07 g), 2017 (36.07 g) and the 5YA (34.94 g).
  • Average U.S. Aggregate kernel volume in 2019 (0.28 cm3) was the same as 2018 and 5YA (both 0.28 cm3) and lower than 2017 (0.29 cm3).
  • The Pacific Northwest ECA had the lowest average 100-k weight and the lowest kernel volume of the ECAs in 2019, 2018, 2017 and the 5YA.
  • U.S. Aggregate kernel true density averaged 1.247 g/cm3 in 2019, which was lower than 2018, 2017 and the 5YA. True density kernel distributions above 1.275 g/cm3 in 2019 indicate softer corn than 2018 and 2017. Of the ECAs, the Pacific Northwest had the lowest true density and lowest test weights in 2019, 2018, 2017 and the 5YA.
  • U.S. Aggregate whole kernels averaged 90.8% in 2019, lower than 2018 (93.0%) and the 5YA (93.3%), but higher than in 2017 (89.9%).
  • Average U.S. Aggregate horneous (hard) endosperm in 2019 (81%) was the same as 2018 and 2017, but higher than the 5YA (80%). The Southern Rail ECA has had the highest or tied for the highest average horneous endosperm in 2019, 2018, 2017 and 5YA among all ECAs. Average horneous endosperm tends to increase in years with higher true density.