NOVEL ONE-STEP PROCESS FOR ENZYMATIC INCORPORATION OF AMINO-ACIDS INTO PROTEINS - APPLICATION TO SOY PROTEIN AND FLOUR FOR ENHANCING THEIR METHIONINE LEVELS

It is known that amino acid esters added in a protein hydrolysate are covalently incorporated during the plastein reaction. As its modification, a novel simplified process was developed which permitted incorporation of L-methionine directly into soy protein during treatment with papain. This process is characterized by its requirement for a very high substrate (protein) concentration and an alkaline pH condition. Racemic DL-methionine ethyl ester could be used to incorporate the L-isomer only. The amount of L-methionine incorporated varied depending on the amount of formulation of L-methionine ethyl ester; it was easily feasible to obtain final products with almost expected methionine contents. From an economic point of view, defatted soy flour was used as starting material, with a satisfactory result that the methionine level was enhanced in a large measure. © 1979 Taylor & Francis Group, LLC.