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 2015/2016, U.S. Export Aggregate protein concentration averaged 10.8%, which falls in the normal range of protein concentration values in literature for U.S. sorghum hybrids.
U.S. Export Aggregate starch concentration averaged 73.0% in 2015/2016, a typical level for any sorghum sample.
U.S. Export Aggregate oil concentration averaged 4.5% in 2015/2016, which falls in the normal range of oil concentration values in literature for U.S. sorghum hybrids.
No difference was observed in average protein concentration between the NOLA (10.8%) and Texas (10.8%) EOs.
Average concentrations for starch and oil for the NOLA EO (73.2% and 4.6%, respectively) were slightly higher than for the Texas EO (72.3% and 4.2%).
Average U.S. Aggregate values for protein and starch were slightly lower at export than at harvest, whereas oil was unchanged. The standard deviations for all of these tests indicated more uniformity (lower standard deviations) at export than at harvest.
All 2015/2016 U.S. Export 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 2015/2016, U.S. Export Aggregate protein concentration averaged 10.8%, which falls in the normal range of protein concentration values in literature for U.S. sorghum hybrids.
- The protein concentration values for the 2015/2016 U.S. Export Aggregate samples had a standard deviation of 0.51%.
- Protein concentration range for the U.S. Export Aggregate samples was from 9.7 to 12.6%.
- Average U.S. Export Aggregate protein was slightly lower than U.S. Harvest Aggregate samples (10.9%). The standard deviation of export samples was much lower than that for the harvest samples (1.02%).
- Protein concentration in the 2015/2016 U.S. Export Aggregate samples was distributed with 2.7% of samples below 10.00%, 93.9% between 10.00 and 11.99%, and 3.3% at or above 12.00%.
- No difference was observed in average protein concentration between the NOLA (10.8%) and the Texas (10.8%) EOs. Both averages fall in the normal range of reported protein concentration values.
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 valueadded 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. Export Aggregate starch concentration averaged 73.0% in 2015/2016, a typical level for any sorghum samples.
- The starch concentration values for the 2015/2016 U.S. Export Aggregate samples had a standard deviation of 0.38%.
- Starch concentration range for the U.S. Export Aggregate samples was from 71.4 to 75.0% in 2015/2016.
- Average U.S. Export Aggregate starch was slightly lower than U.S. Harvest Aggregate samples (73.2%). The standard deviation of export samples was much lower than that for the harvest samples (0.80%).
- Starch concentration in the 2015/2016 U.S. Export Aggregate samples was distributed with 5.5% of samples below 72.00%, 93.9% between 72.00 and 73.99%, and 0.5% equal to or greater than 74.00%.
- Average starch concentration was higher for the NOLA EO (73.2%), with less variability than for the Texas EO (72.3%). Both averages fall in the normal range of reported starch concentration values.
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. Export Aggregate oil concentration averaged 4.5% in 2015/2016, which falls in the normal range of oil concentration values in literature for U.S. sorghum hybrids. The oil concentration values for the 2015/2016 U.S. Export Aggregate samples had a standard deviation of 0.13%.
- Oil concentration range for the U.S. Export Aggregate samples was from 3.7 to 4.9% in 2015/2016.
- Average U.S. Export Aggregate oil was the same as the U.S. Harvest Aggregate samples (4.5%); the standard deviation of export samples was much lower than that for the harvest samples (0.27%).
- U.S. Export Aggregate oil concentration in the 2015/2016 U.S. Export Aggregate samples was distributed with 6.6% of samples at 3.99% or lower, and 93.4% of samples at 4.00 to 4.99%.
- Average oil concentration was higher for the NOLA EO (4.6%), with less variability than for the Texas EO (4.2%). Both averages fall in the normal range of reported oil concentration values.
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 or 4.0 mg CE/g or above. Values below 4.0 mg CE/g generally imply absence of condensed tannins2 ,3.
RESULTS
- Tannin levels in all 2015/2016 U.S. Export Aggregate samples were measured to be less than 4.0 mg CE/g, implying an absence of tannins.
2Awika, J.M. and L.W. Rooney. 2004. Sorghum phytochemicals and their potential impact on human health. Phytochemistry 65, 1199-1221.
3Price, M.L., S. Van Scoyoc and L.G. Butler. 1978. A critical evaluation of vanillin reaction as an assay for tannin sorghum. Journal of Agricultural and Food Chemistry 26, 1214-1218.