Preparation process of yeast glucan

The invention discloses a preparation process of yeast glucan, which comprises the following steps: putting saccharomyces cerevisiae into distilled water, stirring, standing for 30-60 minutes, and then carrying out filter pressing treatment to obtain first filter residues; uniformly stirring the first filter residues with distilled water to form turbid liquid, then freezing the turbid liquid to form ice blocks, and grinding the ice blocks for 3-5 hours to obtain frozen powder; putting the frozen powder into water, uniformly stirring to obtain a turbid liquid, then gradually adding calcium oxide powder, and fully stirring for 2-4 hours to obtain an alkaline extracting solution; adjusting the alkaline extracting solution by using hydrochloric acid, controlling the pH value, then adding alkaline protease, carrying out constant-temperature enzymolysis treatment for 5-10 hours, and centrifuging and washing to obtain an insoluble substance after the enzymolysis treatment is finished; and putting the insoluble subst