The effect of sodium dodecylsulfate on gelatinization and gelation properties of wheat and potato starches

Abstract

The surfactant sodium dodecylsulfate (SDS) has previously been reported to have an influence on the gelatinization and gel forming properties of different starches. In the present study, the effects of SDS were primarily studied by brightfield microscopy and discussed in relation to data obtained by differential scanning calorimetric (DSC) and dynamic rheological measurements on wheat and potato starches. By DSC measurements, it was confirmed that addition of SDS will cause a reduction in the enthalpies of the main endothermic transition and will shift the onset temperatures downwards. Addition of the surfactant will also cause an increase in the enthalpy of the endotherm belonging to the amylose-lipid complex, indicating the formation of an amylose-SDS complex. The micrographs indicated that the staining properties of mainly the amylose fraction was changed in presence of the surfactant. It was also observed that a stepwise increase of the concentration of SDS in starch solutions, heated at constant temperatures, caused swelling, folding, and finally collapse of the granules, indicating an earlier gelatinization. Rheological data, in combination with exothermic DSC-data, showed that the amylose-SDS complex had a profound influence on the elastic properties of the gels. © 1998 Elsevier Science Ltd. All rights reserved.