DETERMINATION OF AMYLOSE BY DIFFERENTIAL SCANNING CALORIMETRY

A differential scanning calorimetry (DSC) method for the determination of amylose as its amylose-L-alpha-lysophosphatidylcholine (LPC) complex is described. Potato amylose/amylopectin mixtures covering the range of 0-95% amylose were heated in the presence of LPC, cooled and then reheated to follow melting of the amylose-LPC complexes formed during the cooling phase. A linear relationship (r = 0.98) was obtained between the amylose content of the mixtures and the enthalpies of the amylose-lipid complexes. This linear calibration was used to predict the amylose content of various native starches, rice flours, wheat flour, durum wheat semolina, and lyophilized raw potato on the basis of the melting enthalpy of their amylose-LPC complexes. Except for the potato samples, amylose contents determined by the DSC method were in good agreement with those obtained from a colorimetric assay.