Finding new sources of alternative plant proteins is necessary to obtain sustainable and affordable foods for the growing global population. Due to limited agricultural resources (land, water, and animal feed), future demands cannot be satisfied by animal-based proteins without drastic adverse impacts on the environment. Cereals are the largest agronomic crops produced globally, and their efficient use would have a large impact on the global economy and food sustainability. Currently cereal processing produces underexploited side-streams, particularly brans. The wheat and rice industries (milling, starch, and bioethanol production) generate substantial volumes of bran-containing side-streams that are rich in protein and generally used for feed or are incinerated. Efficient valorization of side-streams into protein ingredients and their use in healthy protein-enriched foods would contribute to protein security and also provide extensive economic opportunities for new ingredients and food concepts.