Making Kafirin, the Sorghum Prolamin, into a Viable Alternative Protein Source

Kafirin, the sorghum prolamin, is the most hydrophobic of the prolamins, and forms disulfide cross-links because of its high cysteine content. It is noted for its slow digestibility but does not trigger any adverse response when consumed by celiacs. These properties make kafirin potentially valuable in both food and nonfood applications, especially as a bioplastic and encapsulating agent. Despite these valuable properties, to date there is no commercial production of kafirin and consequently no commercial products. Extraction technologies that could be upscaled for industrial use are described. Also, genetic and physicochemical techniques that have been applied to improve the functional and nutritional properties of kafirin as a functional food ingredient and as a bioplastic are reviewed. It is proposed that kafirin extraction and bioplastic manufacture should be located at the site of grain bioethanol production. This would enable the use of a consistent supply of inexpensive, high-protein feedstock from sorghum distillers dried grains with solubles, as well as a ready supply of inexpensive ethanol for extraction. In addition, equipment would be available for solvent recovery, and transportation costs could be minimized. These factors would contribute to making kafirin economically viable as an alternative protein source.