Changing the Amylopectin-Sodium Dodecyl Sulphate Interaction by Modifying the Exterior Chain Length

Abstract

The retrogradation of amylopectin and its interaction with the surfactant sodium dodecyl sulphate (SDS) as a function of the exterior chain length (ECL) of the amylopectin molecules was investigated. Amylopectin was modified by partial beta-amylolysis, which decreased ECL without causing any other changes in the molecular structure. Retrogradation of amylopectin was studied with differential scanning calorimetry (DSC), in the presence and absence of SDS. The retrogradation enthalpy of amylopectin was significantly dependent on the ECL, whereas the melting temperature was only to some extent influenced by ECL. The ability of SDS to inhibit the retrogradation of amylopectin depended on ECL, which suggests that there was a specific binding of SIDS to amylopectin, The decrease in retrogradation when SDS was added to the amylopectin sample was less when ECL decreased. The overall effect was thus an increase in retrogradation in the presence of SIDS when the ECL decreased, Small changes in the molecular structure of amylopectin gave rise to sharp changes in both retrogradation and interaction with lipids, showing that the molecular structure is important for the crystallisation and interaction behaviour of amylopectin.