The preparation method comprises the following steps: mixing vital
gluten and 65%
ethanol according to a
mass ratio of 1: 30, and stirring and extracting in a water bath kettle at 35 DEG C for 3 hours to dissolve
alcohol-soluble
protein in the vital
gluten in the
ethanol; after standing, centrifuging for 5 minutes by using a centrifugal
machine under the condition of 3,500 r / min, taking the precipitate, repeating the steps for dissolving, centrifuging the solution for 5 minutes, and taking the precipitate, namely the
glutenin aggregate. Dissolving the
glutenin aggregate at 30 DEG C for 120 minutes by using 0.1%
sodium hydroxide alkali liquor, standing at 50 DEG C for 12 hours, and regulating the pH value to be neutral to generate precipitate; and centrifuging for 5 minutes to obtain a precipitate which is alkali-soluble
glutenin.
Amylose and alkali-soluble glutenin are mixed according to the
mass ratio of 1: 8-1: 10, drinking water accounting for 3%-5% of the
starch amount is added, mixing is conducted for 30-50 min at the temperature of 30-35 DEG C, and the
disulfide bond content of the alkali-soluble glutenin is reduced by 80% or above.