The invention discloses a preparation method of a soy isolate
protein rich in
branched chain amino acid. The preparation method comprises the following steps: preparing the soy isolate
protein firstly, stirring uniformly, heating, hydrolyzing with
alkaline protease, stabilizing the pH (potential of
hydrogen) within an appointed range in the
hydrolysis process by using NaOH; inactivating the
hydrolysate with boiling water, adjusting the pH value by adding HCl, centrifugally separating, taking supernatant for later use; freeze-
drying the
hydrolysate by a vacuum freeze-
drying machine, and porphyrizing the
hydrolysate to be put into the
drying machine; adjusting the pH value of the solution, and under the presence of L-
cysteine, adding
papain to catalyze the reaction, wherein the
enzyme adding amount is 2%; after the reaction is finished, depositing
protein with
ethanol, centrifugally separating, enabling the protein to pass through a
dialysis bag, centrifugally separating, and freeze-drying, so as to obtain the final product, namely the precipitate. Compared with the prior art, the
branched chain amino acid is introduced into proteins such as
soy protein by using a plastein synthesis method, so as to obtain a plastein product rich in
branched chain amino acid, the purpose of supplementing the branched chain
amino acid can also be achieved after the plastein product is eaten; furthermore, the product is stable in character, preferable in processability, and does not have any bad mouth feel.