Starch-lipid interactions in common, waxy, ae du, and ae su2 maize starches examined by differential scanning calorimetry

Four maize genotypes (common, waxy, ne du, and ne su2) were examined by dif ferential scanning calorimetry (DSC) in the presence of four surfactants (s odium dodecyl sulfate [SDS], dodecyltrimethylammonium bromide [DOTAB], sodi um hexadecyl sulfate [SHS], 1-monolawoyl-rac-glycerol [ML]) to characterize the starch-lipid complexes produced and provide evidence of differences in starch structure. The ionic surfactants with a C-12 hydrocarbon tail reduc ed the gelatinization onset temperature, a phenomenon that does not occur t ypically with neutral surfactants or with surfactants with longer hydrocarb on tails. Subtracting the DSC curves, the exotherm we suspected was caused by starch-lipid complexation, which occurs concomitantly with the gelatiniz ation endotherm, was identified and provided evidence of the existence of a mylopectin-lipid interactions. Apparent starch amylose content correlated w ell with enthalpies of amylose-lipid complexes. Complexes formed from DOTAB produced DSC endotherms that were broad and shallow and that shifted to lo wer temperatures as the DOTAB concentration increased. This was in contrast to other surfactants that normally produce amylose-lipid complex endotherm s at temperatures independent of surfactant concentration.