The invention discloses a method of simultaneously extracting
theanine, rubusoside, and tea
polyphenol from sweet tea. The method comprises following steps: (1)
grinding sweet tea, and percolating sweet tea by cold water to obtain percolate; (2) adsorbing percolate by a
macroporous resin column, and collecting the eluent; (3) adsorbing the eluent by a
polyamide resin column and collecting the eluent; (4) making the eluent go through an
ion exchange resin column, washing the
ion exchange resin column by water, then eluting the
ion exchange resin column by a brine solution, concentrating the eluent, cooling, adjusting the pH to the acidic range, stirring the solution to carry out
crystallization, filtering the solution, washing crystals, and
drying to obtain
theanine. The invention also discloses a method of simultaneously extracting rubusoside, and tea
polyphenol. The contents of obtained
theanine, rubusoside, and tea
polyphenol can reach 98.1%, 99.9%, and 98.3%; the yields can reach 95%, 97%, and 92%; the sweet tea resources are comprehensively utilized, the maneuverability is strong, the cost is low, the
sewage discharge is little, and the method is suitable for industrial production.