A method for separating protein from plant or algae material is disclosed. The method comprises mixing the protein-containing material with a solvent, preferably water； extracting the protein-containing material at p H >； 7； and acidifying the mixture, thereby precipitating protein and fiber together. In some embodiments of the invention, the separation additionally comprises decanting the mixture to recover a protein/fiber solid； adding water to the protein/fiber solid； adding a predetermined quantity of base to the protein/fiber/water system, thereby precipitating fiber； separating the fiber from the protein in a decanter； and drying the protein solution. In other embodiments, the protein/fiber solid is processed directly, e.g. by being passed to an extruder. The use of the fiber as a carrier for the protein makes the inventive method more efficient than methods known in the art； in particular, the inventive method does not require the use of a high-g clarifier centrifuge.
