The invention relates to a preparation method of high-purity fructo-oligose, particularly to a method for preparing fructo-oligose through acidolysis of synanthrin. The method comprises the steps of adding water with certain proportion into pretreated jerusalem artichoke, pulping, adding concentrated sulfuric acid with concentration of 98% into jerusalem artichoke pulp to regulate pH value to be 1-4, carrying out acidolysis for 1-3h at 60-130 DEG C, and performing rough filtration, nanofiltration, ultrafiltration, decoloring, desalting and drying to acid-hydrolyzed liquid to obtain high-purity fructo-oligose powder. The method has the characteristics that sulfuric acid is used for acidolysis of synanthrin to produce fructo-oligose and the enzyme technology is not adopted, so that the production cost is lowered; the nanofiltration and ultrafiltration separation technologies are adopted to separate fructo-oligose, so that large-scale industrial production is realized; the purity of fructo-oligose can reach more than 98%.
; 衣悦涛
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