24 research outputs found
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Investigation of molecular origin and characteristics of maltodextrin-surfactant interactions
The objective of this research was to extend the functionality of maltodextrin in foods, by forming maltodextrin-surfactant complexes that had novel properties not exhibited by maltodextrin alone. To achieve this objective it was necessary to understand the molecular origin and characteristics of maltodextrin-surfactant interactions. A variety of analytical techniques were therefore used to characterize maltodextrin-surfactant interactions. Initial experiments using isothermal titration calorimetry (ITC) and surface tensiometry showed that an anionic surfactant (SDS) bound to maltodextrin when the surfactant concentration exceeded a critical value (∼0.05 mM). ITC showed that the interaction of SDS to maltodextrin was exothermic, which could have been due to an exothermic coil-helix transition and/or an exothermic binding reaction. Surfactant binding to maltodextrin only occurred when the number of monomers in the maltodextrin chain exceeded ∼24 glucose units. NMR studies showed that the interaction involved carbons 1 and 4 of the D-glucopyranose residues of maltodextrin and the surfactant hydrophobic tail, which suggested the formation of a helical inclusion complex. The effect of surfactant type on maltodextrin-surfactant interactions was also investigated. ITC, surface tension and ultrasonic measurements indicated that the charge on the surfactant head group influenced their binding to maltodextrin. Similar amounts of anionic and cationic surfactant bound to maltodextrin, but a much smaller amount of non-ionic surfactant bound. The ITC indicated that surfactants with longer tail groups bound more strongly to maltodextrin than surfactants with shorter ones. The effect of temperature, pH, and salt concentration on maltodextrin-surfactant interactions was studied using ITC. This study indicated that the enthalpy changes associated with surfactant demicellization were highly temperature-dependent. In contrast, the binding of surfactants to maltodextrin was exothermic and relatively temperature-independent. There was no effect of pH on the binding of surfactant to maltodextrin. In contrast, salt concentration affected both surfactant demicellization and surfactant binding to maltodextrin. A potential application of maltodextrin-surfactant complexes was demonstrated by studying the rheology and thermal behavior of maltodextrin solutions in the presence and absence of SDS. The rheology and thermal properties of maltodextrin solutions changed significantly when surfactant was added, e.g. the viscosity increased, gelation occurred, and a melting transition was observed
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Isothermal Titration Calorimetry Study of the Influence of Temperature, pH and Salt on Maltodextrin-Anionic Surfactant Interactions
The effects of temperature (10–50 °C), pH (3–7) and salt concentration (0–100 mM NaCl) on the interactions between maltodextrin (DE=5) and an anionic surfactant (sodium dodecyl sulfate, SDS) were studied using isothermal titration calorimetry (ITC). ITC measurements indicated that the enthalpy changes associated with surfactant demicellization were highly temperature dependent, going from endothermic at higher temperatures to exothermic at lower temperatures. In contrast, the enthalpy changes associated with binding of surfactants to maltodextrin were always exothermic and much less sensitive to temperature. A minimum was observed for both the critical micelle concentration (CMC) of SDS and the apparent CMC (CMC*) of SDS in the presence of maltodextrin at intermediate temperatures (∼30 °C); however, the temperature dependences of the CMC and CMC* were quite small (∼0.5 mM). There was no effect of pH (3, 5, and 7) on surfactant demicellization or binding to maltodextrin. On the other hand, salt concentration (0, 10, and 100 mM NaCl) affected both of these parameters: there being a decrease of CMC and CMC* with increasing salt concentration and a maximum in the amount of surfactant bound to maltodextrin at 10 mM NaCl
Effect of Different Dextrose Equivalent of Maltodextrin on the Interactions with Anionic Surfactant in an Isothermal Titration Calorimetry Study
Effect of Surfactant Type on Surfactant−Maltodextrin Interactions: Isothermal Titration Calorimetry, Surface Tensiometry, and Ultrasonic Velocimetry Study
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Effect of Surfactant Type on Surfactant−Maltodextrin Interactions:  Isothermal Titration Calorimetry, Surface Tensiometry, and Ultrasonic Velocimetry Study
Isothermal titration calorimetry (ITC), surface tensiometry, and ultrasonic velocimetry were used to characterize surfactant−maltodextrin interactions in buffer solutions (pH 7.0, 10 mM NaCl, 20 mM Trizma base, 30.0 °C). Experiments were carried out using three surfactants with similar nonpolar tail groups (C12) but different charged headgroups:  anionic (sodium dodecyl sulfate, SDS), cationic (dodecyl trimethylammonium bromide, DTAB), and nonionic (polyoxyethylene 23 lauryl ether, Brij35). All three surfactants bound to maltodextrin, with the binding characteristics depending on whether the surfactant headgroup was ionic or nonionic. The amounts of surfactant bound to 0.5% w/v maltodextrin (DE 5) at saturation were \u3c0.3 mM Brij35, 1−1.6 mM SDS, and 1.5 mM DTAB. ITC measurements indicated that surfactant binding to maltodextrin was exothermic. Surface tension measurements indicated that the DTAB−maltodextrin complex was more surface active than DTAB alone but that SDS− and Brij35−maltodextrin complexes were less surface active than the surfactants alone
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Two-Dimensional Rotating-Frame Overhauser Spectroscopy (ROESY) and (13)C NMR Study of the Interactions Between Maltodextrin and an Anionic Surfactant
Rotational frame nuclear Overhauser effect spectroscopy (ROESY) and (13)C NMR measurements were carried out to study the molecular interaction between maltodextrin, a digestive byproduct of starch, and an anionic surfactant. Significant differences in chemical shifts were observed when sodium dodecyl sulfate (SDS) was introduced into the maltodextrin (DE 10) solutions. (13)C NMR measurement indicated that there were downfield shifts and broadening of peaks, especially in the region of 75-81 and 100-103 ppm, which were assigned to carbons 1 and 4 of the d-glucopyranose residues of maltodextrin, respectively. ROESY spectra indicated cross-peaks between the SDS and maltodextrin protons. These peaks can arise only in the case of the designated SDS protons and maltodextrin protons being less than 0.5 nm apart for a substantial period of time. The most intense cross-peaks are those between the central CH(2) protons of SDS near 1.2 ppm and the maltodextrin protons ranging from 3.5 to 3.9 ppm. The SDS-H3 CH(2) protons were resolved from the bulk of the SDS protons, with peaks and shoulders at 1.25 ppm, which indicated an especially strong interaction of the SDS hydrophobic tail with MD6 and some less intense interactions with MD2, 4, and 5
Maltodextrin−Anionic Surfactant Interactions: Isothermal Titration Calorimetry and Surface Tension Study
Glycoprotein surfactant interactions:a calorimetric and spectroscopic investigation of the phytase-SDS system
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