29-6 |
Effect of dextrose equivalent (DE) of maltodextrin on its interaction with an anionic surfactant (SDS) |
A. WANGSAKAN1, P. Chinachoti, and D. J. McClements. (1) Department of Food Science, University of Massachusetts, Chenoweth Lab., Amherst, MA 01003 The interaction of maltodextrins with anionic surfactants influences their nutritional, functional and physical attributes. Maltodextrins are available with different average molecular weights, characterized in terms of their dextrose equivalent (DE), depending on the degree of starch hydrolysis. However, little is currently known about the influence of maltodextrin molecular weight on the formation of maltodextrin-surfactant complexes. The objective of this work was to systematically characterize the influence of maltodextrin molecular weight (DE) on its interaction with a model anionic surfactant (sodium dodecyl sulfate, SDS). Isothermal titration calorimetry (ITC) was used to measure the enthalpy changes resulting from mixing of SDS with maltodextrin, whereas a surfactant selective electrode (SSE) was used to measure the fraction of SDS molecules bound to the maltodextrin. SDS-maltodextrin interactions were monitored when 0 to 7 mM SDS were mixed with 0.5% (w/w) maltodextrin (DE=5, 10, 15, 20, and 25) in a Tris-buffer solution, pH 7 at 30.0oC. In the absence of maltodextrin, the enthalpy change was endothermic below the critical micelle concentration (CMC) of SDS because of micelle dissociation, but tended towards zero above it because micelles formed. In the presence of maltodextrin, there was an exothermic contribution to the enthalpy change and an increase in the apparent CMC of the surfactant, which was associated with surfactant binding to the maltodextrin (as confirmed by SSE). The degree of surfactant binding increased with decreasing DE, i.e., increasing molecular weight. The quantitative data generated in this study about surfactant binding to maltodextrin should facilitate the rational design of foods with improved quality and nutritional attributes.
Session 29, Carbohydrate
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