Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2005
Publication Date: 1/31/2006
Citation: Bean, S., Ioerger, B.P., Park, S.H., Singh, H. 2006. Interaction between sorghum protein extraction and precipitation conditions on the yield, purity, and composition of purified protein fractions. Cereal Chem. 83:99-107. Interpretive Summary: Sorghum is a drought resistant, low input cereal grain grown throughout the Central U.S. Most of the sorghum grown in the U.S. is currently used for animal feed. The U.S. exports ~30-50% of its annual sorghum crop. Due to the drought resistant nature of sorghum, it can often be grown in areas where other cereal crops cannot. Thus sorghum represents an important renewable resource that is underutilized for bio-industrial purposes. Past research has shown the potential for sorghum proteins to be used in bio-degradable films and packaging. To realize this potential, improved techniques for extracting sorghum proteins under industrially relevant conditions need to be developed and optimized. This paper evaluates conditions currently used to extract maize proteins for industrial purposes and also investigates methods for producing sorghum protein fractions with unique biochemical properties. Such protein fractions may have unique functional properties that could be tailored for specific uses, thereby increasing their value.
Technical Abstract: Sorghum proteins have the potential to be used in industrial applications such as biodegradable films and packaging. This project was designed to evaluate the extraction of sorghum proteins for potential use in industrial applications. Non-reduced sorghum proteins were extracted with 70% ethanol at 50 C for 1hr, whereas reduced sorghum proteins were extracted in 70% ethanol containing either sodium metabisulfite, cysteine, or glutathione. Proteins were also extracted with 70% ethanol in combination with sonication. Several conditions were used to isolate the proteins via precipitation, including lowering ethanol concentrations, lowering pH to 2.5, and addition of NaCl to the extract. Combinations of these conditions were also tested. Precipitated proteins were characterized by RP-HPLC, SEC, HPCE, and SDS-PAGE. Extraction and precipitation conditions influenced the composition of the purified proteins. Since the extraction and purification processes influenced the composition, purity, biochemical properties; it may be possible to prepare protein fractions with unique functionalities for specific end-uses.