ARS | Publication request: Sorghum protein structure and chemistry: Implications for nutrition and functionality

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: September 26, 2011
Publication Date: April 17, 2012
Citation: Bean, S., Ioerger, B.P., Smith, B.M., Blackwell, D.L. 2012. Sorghum protein structure and chemistry. In: Awika, J., Piironen, V. and Bean, S. R. editors. Advances in Cereal Science: Implications to Food Processing and Health Promotion (ACS Symposium). 2nd edition. Washington, D.C.: American Chemical Society. p. 131-148.

Technical Abstract: Sorghum is the 5th most widely grown cereal crop in the world and has desirable agronomic traits such as drought resistance and heat tolerance. Sorghum is a major food source in developing nations and is widely used as feed grain in Western countries. There is increasing interest in sorghum food products for people with celiac disease in Western countries as well. Sorghum endosperm (grain) proteins are known to have lower in-vitro pepsin digestibility than other cereals in both raw and cooked products. The reasons why sorghum proteins are less digestible than that of other cereals have not yet been completely elucidated. However, several factors have been identified that may play a role in determining the digestibility of sorghum including: physical grain structure, protein body structure, protein cross-linking, starch properties, and phenolic content/composition of the grain. The majority of proteins in sorghum endosperm are found in digestion resistant spherical protein bodies that have highly cross-linked outer layers. Disulfide bond mediated cross-linking increases during cooking of sorghum, resulting in the formation of highly cross-linked web-like structures. Protein digestibility has a substantial impact on the nutritional properties of sorghum utilization in the production of human foods, animal feeds, and for bio-industrial uses such as ethanol production. The unique properties of sorghum proteins may also influence the digestion of sorghum starch and could play a role in development of low glycemic index foods.