Sorghum proteins: the concentration, isolation, modification, and food applications of kafirins

Celiac disease is a serious condition affecting millions of individuals. Those afflicted with this illness are resigned to a lifelong avoidance of products containing the storage prolamin proteins found in cereal grains wheat, rye, and barley. Since many food products are based on these cereals, especially wheat, celiac patients have very limited food choices, and those that are available to them are generally poor in quality, often nutritionally deficient, and expensive. Furthermore, this condition also indirectly affects their families and friends with whom they share meals. Thus, a burgeoning need exists to develop nutritious, palatable, and affordable foods, especially staples like bread and pasta, for these individuals and their families and friends who are accustomed to wheat based products. Grain sorghum and its proteins are safe for celiac patients and individuals with varying levels of gluten intolerances. However, the main sorghum proteins, kafirins, are resistant to digestion. They are also difficult to extract and modify in an industrial-scale process and with food-compatible chemicals, thus limiting their use in foods. This review describes studies on kafirin extraction and methods for modifying sorghum proteins for improved nutrition and functionality, as well as food applications. Armed with this knowledge, scientists and technologists will be in a better position to identify opportunities that will further enhance the nutritional and functional value of sorghum proteins.