Concerning the Identity of the Proteins Extracted From Wheat Flour by the Usual Solvents

Wheat flour was found by Osborne and Voorhees' to contain five distinct proteins: an albumin (leucosin), a globulin, a prolamin (gliadin), a glutelin (glutenin), and a proteose.The albumin is soluble in water, and both it and the globulin are soluble in dilute saline solutions.Gliadin is slightly soluble in water, and freely soluble in 50 to 70 per cent, alcohol solutions.Glutenin is insoluble in water, saline solutions, and alcohol, but is dispersed by dilute acid and alkaline solutions.The existence in wheat flour of a proteose as such has been questioned.For the purposes of this work it has not been considered as present in appreciable quantities.The gliadin and glutenin constitute what is commonly known as gluten, and represent from 85 to 88 per cent of the total protein of a high grade flour.These are believed by Osborne2 to be the only proteins present in the endosperm of the wheat kernel in any considerable amount.Ritthausen's conclusion that wheat flour contains three distinct proteins soluble in dilute alcohol was not supported by the work of Osborne, who found the fractional precipitations of the protein material soluble in alcohol to yield prmtically the same percentages of glutamic acid.In view of the similarity in the chemical and physical properties of these fractions, Osborne contends that only one alcoholsoluble protein is present.This view has since been generally