The invention discloses high-purity resistant
dextrin and a preparation method thereof, and the preparation method comprises the following steps: (1) adding 4, 3-alpha-
glucosyltransferase into a
maltodextrin aqueous solution or a
starch solution treated by
starch debranching
enzyme to react, and after the reaction is finished, deactivating the
enzyme; (2) adding alpha-
amylase into a reactant in the step (1) to react, and deactivating the
enzyme after the reaction is finished; (3) adding alpha-
glucosidase into the reactant in the step (2) for reaction, and deactivating the enzyme after the reaction is finished; (4) adding saccharifying enzyme into the reactant in the step (3) to react, and deactivating the enzyme after the reaction is finished; and (5) adding
yeast powder into the reactant in the step (4) for
fermentation, filtering by a filter membrane after
fermentation, collecting membrane filtrate, and
drying to obtain the high-purity resistant
dextrin. The preparation process is simple and efficient, the product purity is high, the proportion of alpha-1, 3 glucosidic bonds in the prepared resistant
dextrin is 40% or above, and the purity of the resistant dextrin is 80-90%.