Abstract: A method for fraction fractionation of a vegetable protein such as soybean protein which comprises subjecting a source of the vegetable protein in an aqueous system to reduction conditions such as treatment with a sulfite compound, a glutathione compound or cysteine compound, or electrolytic reduction at pH within a neutral or alkaline range and then bringing the system to pH of 5.5 to 7.0 at a temperature of 20.degree. C. or lower to fractionate the system into a soluble or dispersing fraction and an insoluble or precipitate fraction.

Abstract: A method for drying a water retentive substance such as okara which comprises adjusting the shape of a water retentive substance having a water content of 55 to 95% by weight to particles having a particle size of 1.5 to 13 mm and drying by using a novel improved pneumatic conveying drying apparatus comprising a dryer section, a pulverizer section provided at the lower part of the dryer section and a classifier section at the upper part of the dryer section, the substance to be dried being fed to the dryer section at a site at least 500 mm above the pulverizer section. The novel drying apparatus is also provided.

Abstract: A novel phosphorylated soybean protein showing good functional properties at a wide pH range including an acidic pH range which comprises soybean protein and ortho-phosphate bonded to lysine and histidine residue constituents of the soybean protein, the ratio of bonded phosphorus to nitrogen in the soybean protein being 25 .mu.g/mg nitrogen or more and the isoelectric point of the phosphorylated soybean protein being pH 3.5 or lower.