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Corn Export Cargo Quality Report 2012/2013

Contents

  1. Export Cargo Quality Highlights
  2. Introduction
  3. Quality Test Results
  4. Moisture
  5. Chemical Composition
  6. Physical Factors
  7. Mycotoxins
  8. U.S. Corn Export System
  9. U.S. Export Corn Flow
  10. Impact of the Corn Market Channel on Quality
  11. U.S. Government Inspection and Grading
  12. Survey and Statistical Analysis Methods
  13. Survey Design and Sampling
  14. Statistical Analysis
  15. Testing Analysis Methods
  16. Corn Grading Factors
  17. Moisture
  18. Chemical Composition
  19. Physical Factors
  20. Mycotoxin Testing
  21. U.S. Corn Grades and Conversions
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III. QUALITY TEST RESULTS

A. Grade Factors

The USDA’s Federal Grain Inspection Service (FGIS) has established numerical grades, definitions and standards for grains. The attributes which determine the numerical grades for corn are test weight, broken corn and foreign material (BCFM), total damage, and heat damage. The table for “Corn Grades and Grade Requirements” is provided on page 42 of this report.

SUMMARY: GRADE FACTORS AND MOISTURE

  • Quality of the corn at export was good, with average values generally better than grade limits and contract specifications. As expected, quality at export was more uniform than at harvest.
  • Test weight was high with U.S. Aggregate samples averaging 58.1 lb/bu (74.8 kg/hl).
  • Average BCFM at export was below the limits for the respective grades.
  • Average total damage and heat damage were well below the limits for the grade being loaded.
  • Moisture contents were lowered between harvest and export, in part to meet the contract specifications at export, and were generally at levels for safe transit.
  • Quality of the 2012/13 corn at export was better than that of 2011/12 corn at export on all grade factors except total damage (2.0% in 2012/13 compared to 1.7% in 2011/12). These were still low values, well below the maximum limits for U.S. No. 1 of 3%. With low total damage and low moisture, the 2012/13 export samples should travel in good condition.

1. Test Weight

Test weight (weight per volume) is a measure of bulk density and is often used as a general indicator of overall quality and as a gauge of endosperm hardness to alkaline cookers and dry millers. It reflects kernel hardness and kernel maturity. Test weight is initially impacted by genetic differences in the structure of the kernel. However, it is also affected by moisture content, method of drying, physical damage to the kernel (broken kernels and scuffed surfaces), foreign material in the sample, kernel size, stress during the growing season, and microbiological damage. High test weight at the port generally indicates high quality, high percent of horneous (or hard) endosperm and sound, clean corn.

HIGHLIGHTS

  • U.S. Aggregate average test weight of 58.1 lb/ bu (74.8 kg/hl) at export indicates overall good quality, is 2 lb/bu above the grade limit for U.S. No. 1 corn (56.0 lb/bu) and is higher than last year. Nearly 97% of the samples were at or above the 56.0 lb/bu minimum limit for No. 1 grade.
  • Test weight at export was lower than test weight at harvest (58.8 lb/bu), resulting from higher BCFM, lower moisture, and higher damage.
  • Variation in the 2012 crop was less in the export samples than in harvest samples. As corn is commingled moving through the marketing channel, test weight may change somewhat but it becomes more uniform with lower standard deviation and smaller range between maximum and minimum values.
  • Over 95% of all samples’ test weights were at or above the minimum for U.S. No. 1 grade, and 100% were above the limit for U.S. No. 2 grade.
  • Test weight was significantly higher in samples from the Gulf ECA (58.4 lb/bu) with lower variability than samples from the Pacific Northwest ECA

2. Broken Corn and Foreign Material (BCFM)

Broken corn and foreign material (BCFM) is an indicator of the amount of clean, sound corn available for feeding and processing. As corn moves through the market channel, each impact of the grain during handling and transporting increases the amount of broken corn. As a result, the average BCFM in most shipments of corn will be higher at the port than at the country elevator level.

Broken corn (BC) is defined as corn and corn material small enough to pass through a 12/64th inch round-hole sieve, but too large to pass through a 6/64th inch round-hole sieve.

Foreign material (FM) is defined as any non-corn pieces too large to pass through a 12/64th inch sieve, as well as all fine material small enough to pass through a 6/64th inch sieve.
The diagram to the right illustrates the measurement of broken corn and foreign material for the U.S. corn grading standards.

HIGHLIGHTS

  • BCFM in U.S. Aggregate export samples was significantly lower in 2012/13 (2.7%) than in 2011/12 (3.0%). Average values were below the limit of 3.0% for U.S. No. 2 in the aggregate and in all ECAs.
  • Export samples were very clean with 64.2% at or below the 3% maximum for Grade 2.
  • The increase in BCFM between harvest (0.8%) and export (2.7%) is the result of increased breakage during drying and handling.
  • Corn arriving at the export point is often commingled from many origins to meet the contracted grade limits, as indicated by the lower level of BCFM in U.S. No. 2 o/b (2.6%) than in U.S. No. 3 o/b (3.3%). U.S. Aggregate BCFM for each contract grade category was below the limits for the respective contract grade.
  • BCFM at export was lower in the Southern Rail ECA than in either the Gulf or Pacific Northwest ECA.

3. Total Damage

Total damage is the percentage of kernels and pieces of kernels that are visually damaged in some way, including damage from heat, frost, insect, sprout, disease, weather, ground, germ, and mold. Most of these types of damage result in some sort of discoloration or change in kernel texture. Damage does not include broken pieces of grain that are otherwise normal in appearance. Mold damage and the associated potential for mycotoxins is the damage factor of greatest concern. Mold damage is usually associated with higher moisture content and high temperature during growing and/or storage conditions.

Corn with low levels of total damage is more likely to arrive at destination in good condition than corn with high levels of total damage. High levels of total damage have the potential of increasing moisture and microbiological activity during transport.

HIGHLIGHTS

  • U.S. Aggregate total damage at export (2.0%) was higher in 2012/13 than in 2011/12 (1.7%), but still below the limit for U.S. No. 1 corn. Variability was also higher as indicated by the standard deviation and range.
  • The average level for total damage increased significantly between the 2012 harvest (0.8%) and the 2012/13 exports (2.0%) but was still below the limit for U.S. No.1.
  • 82.4% of the export samples had 3.0% or less damaged kernels – well below the limit for U.S. No. 2 of 5.0%. Only 7.1% of the samples were above the limit for grade 2.
  • Total damage was highest in the Gulf ECA, and the increase in total damage between harvest and export was greatest in the Gulf ECA, most likely due to higher moisture corn at harvest.
  • Total damage was well below the limits for each contract grade.

4. Heat Damage

Heat damage is a subset of total damage in corn grades and has separate allowances in the U.S. Grade standards. Heat damage can be caused by microbiological activity in warm, moist grain or by high heat applied during drying. Low levels of heat damage may indicate the corn has been stored at appropriate moisture and temperatures prior to delivery to the port.

HIGHLIGHTS

  • Only a few samples showed any heat damage, indicating good management of drying and storage of the corn through the market channel.