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Starch-Lipid Interactions in Common, Waxy, ae du, and ae su2 Maize Starches Examined by Differential Scanning Calorimetry¹

¹Journal paper No. 15867 of Purdue Agricultural Research Programs. ²Food Technology, Center for Chemistry and Chemical Engineering, Lund University, Lund, Sweden S221 00. ³Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907-1160. ⁴Corresponding author. E-mail: bemiller@purdue.edu

Four maize genotypes (common, waxy, ae du, and ae su2) were examined by differential scanning calorimetry (DSC) in the presence of four surfactants (sodium dodecyl sulfate [SDS], dodecyltrimethylammonium bromide [DOTAB], sodium hexadecyl sulfate [SHS], 1-monolauroyl-rac-glycerol [ML]) to characterize the starch-lipid complexes produced and provide evidence of differences in starch structure. The ionic surfactants with a C₁₂ hydrocarbon tail reduced the gelatinization onset temperature, a phenomenon that does not occur typically with neutral surfactants or with surfactants with longer hydrocarbon tails. Subtracting the DSC curves, the exotherm we suspected was caused by starch-lipid complexation, which occurs concomitantly with the gelatinization endotherm, was identified and provided evidence of the existence of amylopectin-lipid interactions. Apparent starch amylose content correlated well with enthalpies of amylose-lipid complexes. Complexes formed from DOTAB produced DSC endotherms that were broad and shallow and that shifted to lower temperatures as the DOTAB concentration increased. This was in contrast to other surfactants that normally produce amylose-lipid complex endotherms at temperatures independent of surfactant concentration.