Protein isolates are recovered from vegetable protein sources, such as sunflower meal, by extracting the meal with an alkali solution in the presence of an alkali metal borohydride, and then acid precipitating the resulting aqueous protein extract phase to produce a protein isolate. Typically, the alkali metal borohydride is employed in an amount of at least about 20 ppm, based on the combined weight of vegetable meal and alkali solution. Protein isolates produced by this process exhibit improved color, palatability and/or nutritional value, and comprise highly desirable additives for food products, animal foods, etc.