Effects of using defatted gluten as a substrate for solubilization with sodium hydroxide

Abstract

SummaryWhen vital wheat gluten is treated with 0.25 M sodium hydroxide, its solubility is greatly improved, permitting a protein solution in excess of 100 mg/ml in water. This product has proved useful for industrial and food uses, but for use in bland foods it suffers from the disadvantage of possessing a soapy taste. In an attempt to overcome this problem, flour was defatted by solvent extraction and gluten was handwashed from it. When this defatted gluten was treated with alkali under similar conditions, it lacked the soapy taste but it was rendered soluble to the extent of only 20–30 mg/ml. Alkali treatment of defatted gluten or normal gluten resulted in the deamidation of approximately the same amount of the total glutamine + asparagine residues in either case. The lack of solubility of the alkali‐treated defatted gluten is attributed to the absence of sodium salts of fatty acids. It is proposed that the effectiveness of sodium hydroxide in solubilizing normal gluten is derived from the hydrolysis of the lipids present in gluten to their respective fatty acid salts. If the same high degree of solubility is to be retained, methods other than the treatment of defatted gluten must be used to overcome the flavour problem where necessary.