Determination of amylose content in different starches using modulated differential scanning calorimetry

A simple calorimetric method for determination of amylose content in starch is reported. Starches were heated in the presence of two common surfactants, viz., sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB), and the enthalpies of melting of the amylose-surfactant complexes were determined using Modulated Differential Scanning Calorimetry (MDSC). A large number of native starches including cereal, root and pea starches were examined. The results were compared with those obtained by iodimetry and gel permeation chromatography (GPC) for all the starches. There was a good correlation between the values from iodimetry and GPC with those obtained using the surfactants. Both surfactants seemed to work equally well, even for those starches with about 40% amylose content. However, in case of SIDS higher standard deviations were usually obtained than for CTAB in the determination of transition enthalpies.