The invention provides an extraction method for
resveratrol from giant knotweed
rhizome. Plants like giant knotweed
rhizome, peanut
rhizome, branches and leaves of grape and mulberry leaves having undergone
enzymatic hydrolysis and
fermentation can be used as raw materials. The extraction method comprises the following steps: adding
superoxide dismutase according to the proportion of the raw materials and then adding an
ethanol solvent with a concentration of 80% for extraction; combining obtained extracts, carrying out vacuum concentration and complete
recovery of
ethanol, adding a saturated
chitosan solution into an obtained concentrate, and allowing an extract to be precipitated in a deposition manner; adding an
ethanol solvent weighing 20 times of an obtained precipitate and having a concentration of 40% to dissolve the precipitate, then carrying out filtering, concentrating a filtrate, adding a
chitosan solution into the concentrated filtrate and carrying out standing and
centrifugation at normal temperature so as to obtain a
solid precipitate; and adding an ethanol
solvent weighing 20 times of the
solid precipitate and having a concentration of 40% to dissolve the
solid precipitate, then carrying out filtering, concentrating a filtrate, adding a
chitosan solution into the concentrated filtrate, carrying out standing and
centrifugation at normal temperature so as to obtain a solid precipitate and washing the solid precipitate with
purified water until a washing liquid does not contain a
pigment; and successively carrying out
vacuum drying and crushing so as to obtain a product with purity of 50 to 60%. Compared with a conventional production method, the extraction method provided by the invention enables yield of
resveratrol to be increased by more than 30%.