13—The Fractionation of Starch

Abstract
A general method for the fractionation of amyloses has been developed. It is based on the discovery that their fractional solubilities in water saturated with butanol are functions of temperature and molecular size over a small temperature range, and has been applied to sago and tapioca amyloses. The rigidities of aqueous gels of the fractions and the intrinsic viscosities and number-average degrees of polymerisation of their triacetates have been determined and compared with corresponding data for one sample of maize amylose and two samples of maize crystalline amylose. The relations between intrinsic viscosity and degree of polymerisation and gel rigidity and degree of polymerisation differ for the different amyloses. These differences suggest that the amyloses may be slightly branched, the amount of branching varying from one to another.