Sorghum

What is Sorghum?

Different varieties of sorghum range in color from white and pale yellow to deep red, purple and brown. Sorghum is used as a feed  for cattle and poultry, as well as human consumption. It is often the only source of energy and protein in some parts of Africa and India.

The lack of gluten makes it a valuable grain for formulating bakery and other food products for people with celiac disease. The USDA categorizes its grains into four classifications based on structural characteristics:²

• Mixed Sorghum
• White Sorghum
• Tannin Sorghum
• Sorghum

Origin

Sorghum is believed to have originated in Central Africa between 4500 and 1000 BC.  From there it spread into other parts of Africa, mainly Sudan, Egypt and Nigeria and Asia (India). Today, it is grown throughout the world, with the majority (∼55%) produced in Asia and Africa, followed by the United States which produces 30% of the global supply. The remainder is grown in the dry regions of Central and South America, mainly Colombia and Venezuela.³

Sorghum grain is an important food in arid parts of the world due to the crop’s drought tolerance.³

Function

Due to the lack of gluten, it has poor rheological properties and inadequate  bread-making qualities. Sorghum-based doughs behave more like batters than doughs. To compensate for these drawbacks, composites of sorghum and other flours have been used in bread formulations.

A study on cookies and cakes by Oyidi  used a combination of sorghum flour and starch to produce an acceptable cake.³ However, cookies produced with 100% sorghum flour were tough and gritty.³

Breads made with sorghum composite flours were found by trained panelists to display hay-like aroma with slight sourness and astringency. Textural differences were also noted between sorghum and rye-based breads.⁴

Nutrition

Sorghum grains are rich in carbohydrates, especially those with slow digestibility.⁵ They contain moderate levels of protein with low levels of lysine but are gluten free. Similar to other cereals, it is a good source of B-vitamins. The grain also contains beneficial phytochemicals such as flavonoids which were reported to help retard tumor development.⁶

Sorghum’s slow starch digestibility is a result of its restricted endosperm accessibility as well as the presence of tannins. This quality has been found to be effective in reducing insulin (~55%) and glucose (35%) responses in healthy individuals who consumed muffins containing its flour.⁸  

Application

The applications fall into two main categories:

1. Flour: The  grain may be ground into flour or meal and further used in making chapatis and other unleavened breads in India and some African countries. Recently, sorghum flour has been incorporated into gluten-free baked goods such as tortillas, porridge, gruel, fermented and unfermented flat breads, chips and many others.
2. Grains: the grains are used in breakfast cereals and nutritional bars as well as in multigrain breads. It can also be boiled and consumed as an alternative to rice.

FDA regulation

Under FDA labeling guidelines, Sorghum is classified as a whole grain.⁹

References

1. “United States Department of Agriculture.” Agricultural Marketing Service, www.gipsa.usda.gov/fgis/commgallery/gr_grsorghum.aspx.
2. “Official US Standards for Grain Sorghum.” United States Department of Agriculture, 6AD. https://www.gipsa.usda.gov/fgis/standards/810sorghu.pdf
3. Arendt, E, and F Dal Bello. Gluten-Free Cereal Products and Beverages. Academic, 2008. pp 101-112
4. Hart, M. R., Graham, R. P., Gee, M., and Morgan Jr., A. I. (1970). Bread from sorghum and barley flours. J. Food Sci. 35, 661–665
5. Carson, L., Setser, C. and Sun, X.S. Sensory characteristics of sorghum composite bread. Food Sci. Technol. 2001, 35, 5: 465-471.
6. Klopfstein, C.F. and Hoseney, R.C. Nutritional properties of sorghum and the millets. In “Sorghum and millets Chemistry and technology”, (D.V. Dendy, Ed.). American Association of cereal Chemists, St. Paul, MN., 1995, pp: 125-168.
7. Huang, M.T. and Ferraro, T. Phenolic compounds in food and cancer prevention. ACS Symposium, 1992, 507: 8-34.
8. 8.  Poquette, N.M., Gu, X. and Lee, S.-O., grain sorghum muffin reduces glucose and insulin responses in men. Food Funct. 2014, 5: 894-899.
9. Center for Food Safety and Applied Nutrition. “Guidance & Regulation – Draft Guidance for Industry and FDA Staff: Whole Grain Label Statements.” U S Food and Drug Administration Home Page, Center for Biologics Evaluation and Research, www.fda.gov/Food/GuidanceRegulation/ucm059088.htm.