| 摘要 |
The process for fractionating starch disclosed in the parent Specification is modified in that the starch is dissolved, with the application of heat and pressure, in an aqueous solution of magnesium sulphate and/or sodium sulphate and/or ammonium sulphate, the solution is cooled, e.g. to between 20 DEG and 25 DEG C., until both amylose and amylopectin are precipitated, the precipitate is separated from the mother liquor and mixed with water e.g. at a temperature between 60 DEG and 80 DEG C., to dissolve the amylopectin, the undissolved amylose is separated from the amylopectin solution and the salt concentration of the latter is then increased to precipitate the amylopectin. The starch may be dissolved at a temperature between 120 DEG and 160 DEG C., e.g. in an autoclave, in an aqueous solution containing 25 to 30 g magnesium sulphate heptahydrate per 100 cc. The solution may contain a reducing substance, e.g. sodium sulphite, which is stable in the solution at the temperature at which the starch is dissolved.
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