kafirin

Kafirin refers to a group of prolamin storage proteins found in the seeds of sorghum (Sorghum bicolor). They are the major protein components of the sorghum endosperm and accumulate in protein bodies as part of the seed’s nitrogen reserve. Kafirins are considered the sorghum equivalent of gluten proteins in wheat, but they are not gluten and sorghum is widely used in gluten-free foods.

The kafirin family is divided into several subfamilies, commonly designated as alpha-, beta-, gamma-, and delta-kafirins. These proteins are rich in the amino acids proline and alanine and are relatively low in lysine and tryptophan, contributing to the characteristic amino acid profile of sorghum. Their compact structure and abundance in the endosperm influence the physical properties of sorghum flour and can affect dough behavior in sorghum-based products.

Nutrition and processing implications are linked to their amino acid composition and digestibility. The low lysine content of kafirins can limit protein quality in sorghum-based diets, a concern that can be mitigated by combining sorghum with other protein sources such as legumes or by processing methods that improve protein availability. Kafirin content also affects how sorghum proteins behave during milling, fermentation, and thermal processing, influencing texture and sensory properties of resulting foods.

Genetically, kafirin genes are encoded by a multigene family expressed in the endosperm. Breeding and biotechnological approaches aim to modify kafirin composition or expression to enhance overall protein quality and kernel characteristics. While kafirins are prolamins like those in gluten-containing cereals, they are not associated with celiac disease, and sorghum remains gluten-free.