2015/2016 Sorghum Harvest and Export Quality Report

B. Moisture

Moisture content (water weight in kernels per total weight of kernels (i.e., water plus dry matter)) is reported on offcial grade certifcates, but does not determine which numerical grade will be assigned to the sample. Moisture content affects the amount of dry matter being sold and purchased. Also an indicator for potential drying, moisture has potential implications for storability, and affects test weight. Higher moisture content at harvest increases the chance of kernel damage occurring during harvesting and drying. Moisture content and the amount of mechanical drying required will also affect stress-crack formation, breakage, and germination. Extremely wet kernels may be a precursor to high mold damage later in storage or transport. While the weather during the growing season affects yield and the development of the kernels, harvest moisture is influenced largely by the timing of harvest and harvest weather conditions.

RESULTS

  • The U.S. Harvest Aggregate moisture contents recorded at the elevator in the 2015 samples averaged 14.1%, with a minimum value of 10.1% and a maximum value of 17.9%.
  • The moisture content values for the 2015 U.S. Harvest Aggregate samples had a standard deviation of 1.19%.
  • The 2015 U.S. Harvest Aggregate moisture values were distributed with only 52.1% of the samples containing 14% or less moisture. The 14% moisture level is the base moisture used by most elevators for discounts and is a level considered safe for storage for short periods during low winter-time temperatures.
  • Late Harvest average moisture content (14.0%) in 2015 was slightly lower than Early Harvest average moisture content (14.5%). The difference may have been attributable to greater in-field dry down for Late Harvest samples than Early Harvest samples due to a longer harvest window and more favorable weather conditions during harvest.

C. Chemical Composition

Chemical composition of sorghum is important because the components of protein, starch, oil and tannins are of signifcant interest to end users. The chemical composition attributes are not grade factors. However, they provide additional information related to nutritional value for livestock and poultry feeding and other processing uses of sorghum. Unlike many physical attributes, chemical composition values are not expected to change signifcantly during storage or transport.

SUMMARY: CHEMICAL COMPOSITION

  • In 2015, U.S. Harvest Aggregate protein concentration averaged 10.9%, with a range from 6.8 to 14.1%.
  • Protein concentration in the 2015 U.S. Harvest Aggregate samples was distributed with only 9% of samples below 9.0%, 41% between 9.0 and 10.99%, and 51% at or above 11.0%.
  • U.S. Harvest Aggregate starch concentration averaged 73.2% in 2015, with a range from 68.7 to 75.6%.
  • Starch concentration in the 2015 U.S. Harvest Aggregate samples was distributed with 34% of samples between 70.00 and 72.99%, 46% between 73.00 and 73.99%, and 20% equal to or greater than 74.00%. U.S. Harvest Aggregate oil concentration averaged 4.5% in 2015, with a range from 3.0 to 5.1%.
  • Almost two-thirds of 2015 U.S. Harvest Aggregate samples (66%) had an oil concentration at 4.50% and higher, with 20% of samples at 4.00 to 4.49% and 14% at 3.99% or lower.
  • All 2015 U.S. Harvest Aggregate samples were considered tannin-free.

1. Protein

Protein is very important for poultry and livestock feeding, as it supplies essential sulfur-containing amino acids and helps to improve feed conversion effciency. Protein is usually inversely related to starch concentration. Results are reported on a dry basis.

RESULTS

  • In 2015, U.S. Harvest Aggregate protein concentration averaged 10.9%, which is in the range of typical protein concentration values in literature for U.S. sorghum hybrids.
  • The protein concentration values for the 2015 U.S. Harvest Aggregate samples had a standard deviation of 1.02%.
  • Protein concentration range for the U.S. Harvest Aggregate samples was from 6.8 to 14.1% in 2015.
  • Protein concentration in the 2015 U.S. Harvest Aggregate samples was distributed with only 8.7% of samples below 9.00%, 40.6% between 9.00 and 10.99%, and 50.8% at or above 11.00%.
  • Late Harvest samples had an average protein concentration of 11.1%, whereas the Early Harvest samples had an average protein concentration of 10.4%.

2. Starch

Starch is an important factor for sorghum and is related to metabolizable energy for livestock and poultry. Levels of starch in sorghum may also be of interest to processors, as starch provides the substrate for several value-added processes. High starch concentration is often indicative of good kernel maturation/filling conditions and reasonably moderate kernel densities. Starch is usually inversely related to protein concentration. Results are reported on a dry basis.

RESULTS

  • U.S. Harvest Aggregate starch concentration averaged 73.2% in 2015, a typical level for any commercial hybrid sorghum sample.
  • The starch concentration values for the 2015 U.S. Harvest Aggregate samples had a standard deviation of 0.80%.
  • Starch concentration range for the U.S. Harvest Aggregate samples was from 68.7 to 75.6% in 2015.
  • Starch concentration in the 2015 U.S. Harvest Aggregate samples was distributed with 33.8% of samples between 70.00 and 72.99%, 46.4% between 73.00 and 73.99%, and 19.8% equal to or greater than 74.00%.
  • Average starch concentration for Late Harvest samples (73.2%) was essentially the same as that for Early Harvest samples (73.3%), but the range in Late Harvest starch values (68.7 to 75.6%) was greater than the range in Early Harvest samples (71.1 to 75.0%). The larger geographical area in which Late Harvest hybrids were grown likely contributed to the larger range of values in starch concentration.

3. Oil

Oil is an essential component of poultry and livestock rations. It serves as an energy source, enables fat-soluble vitamins to be utilized, and provides certain essential fatty acids. Oil may also be an important co-product of sorghum value-added processing. Results are reported on a dry basis.

RESULTS

  • U.S. Harvest Aggregate oil concentration averaged 4.5% in 2015, which is in the normal range of typical oil concentration values in literature for U.S. sorghum hybrids. The oil concentration values for the 2015 U.S. Harvest Aggregate samples had a standard deviation of 0.27%.
  • Oil concentration range for the U.S. Harvest Aggregate samples was from 3.0 to 5.1% in 2015.
  • Almost two-thirds of 2015 U.S. Harvest Aggregate samples (66.1%) had an oil concentration at 4.50% and higher, with 19.8% of samples at 4.00 to 4.49%, and 14% at 3.99% or lower.
  • Late Harvest samples had an average oil concentration of 4.6%, whereas the Early Harvest samples had an average oil concentration of 4.3%.

4. Tannins

Tannins are present in sorghum varieties that have a pigmented testa within their kernels. Chemically, tannins are compounds that are large molecules comprised of smaller phenolic molecules (catechins, epicatechins, etc.) and are widely distributed in nature (compounds found in grapes, bark, tea leaves, etc. that influence aroma, flavor, mouth-feel and astringency, and have antioxidant and other possible health benefts). While present in sorghum varieties grown around the world, more than 99% of sorghum currently grown in the United States is tannin-free due to decades of breeding efforts to eliminate tannins from sorghum hybrids. Tannins have effects on nutritional and functional properties as a result of interactions of the tannins with nutrients in the kernel. Livestock and poultry growth performance can be negatively affected by the presence of tannins in sorghum-containing rations. Current non-tannin sorghums grown in the United States have virtually the same energy profile as corn in feed rations. Results are reported as being below 4.0 milligrams of catechin equivalents (CE) per gram sample (4.0 mg CE/g) or above. Values below 4.0 mg CE/g generally imply absence of condensed tannins2, 3.

RESULTS

  • All observed tannin levels in the 2015 U.S. Harvest Aggregate samples (includes all Late and Early Harvest samples) were less than 4.0 mg CE/g, implying an absence of tannins.

2Awika, J.M., L.W. Rooney, 2004. Sorghum phytochemicals and their potential impact on human health. Phytochemistry 65, 1199-1221.
3Price, Martin L., Van Scoyoc, S., Butler, L.G., 1978. A critical evaluation of vanillin reaction as an assay for tannin sorghum. Journal of Agricultural and Food Chemistry 26, 1214-1218.