Method of separation of the amylose and amylopectin

摘要

Substantially fat-free retrograded amylose is prepared by dissolving retrograded amylose in a mixture consisting essentially of water and an alcohol having 4 to 6 carbon atoms, at a temperature of from 250 DEG F. to the temperature at which amylose tends to degrade, the period during which the solution remains at the temperature being limited to avoid substantial degradation of the amylose, the proportions of water and alcohol in the mixture being such that separable water and alcohol layers can be formed at a temperature below the atmospheric boiling-point of the water-alcohol mixture but at 120 DEG F. or above the amount of impure retrograded amylose dry substance being not more than 15% by weight based on the weight of the water in the water-alcohol mixture, cooling the solution to a temperature below the atmospheric boiling-point of the water-alcohol mixture but not less than 120 DEG F., maintaining the solution at a temperature of from 120 DEG F. to the boiling point of the mixture for a time sufficient to form an upper alcohol layer and a lower water layer, separating the two layers, and recovering substantially fat-free amylose from the water layer. The water/alcohol mixture is preferably heated rapidly to above 250 DEG F. by mixing with steam at super-atmospheric pressure. The mixture may be maintained at a temperature between 120 DEG F. and the boiling point for a time sufficient to allow solid amylose to form in the water layer, from which it may be separated by conventional methods. Alternatively, the amylose may be precipitated from the water layer, before any solid amylose has formed, by an organic liquid, e.g. pyridine, alcohols or ketones. To ensure separation of aqueous and alcoholic layers at the required temperature, the water/alcohol mixture contains not less than 8% alcohol, based on the weight of water. Preferably the weight of impure amylose used is less than 9%, in which case the amylose may be separated from residual branched-chain material, the latter remaining in solution while amylose solidifies in the water layer. Specifications 895,215 and 923,240 is referred to.