Aqueous Solutions Of D-fructose Research Articles

Study of solute–solute and solute–solvent interactions of N-acetyl glycine in aqueous d-fructose solutions at different temperatures

Densities (ρ) and ultrasonic speeds (u) for N-acetyl glycine (AG) in (0.05, 0.15, 0.25 and 0.35molkg−1) aqueous d-fructose (FR) solutions have been measured at temperatures (288.15, 293.15, 298.15, 303.15 and 308.15)K and at pressure 101kPa. These data have been used to calculate apparent molar volume (Vϕ) and acoustical parameters, coefficient of isentropic compression (βs), molal hydration number (nH) and apparent molar isentropic compression (Kϕ,s). Partial molar volumes (Vϕ0) and partial molar isentropic compression (Kϕ,s0) of AG at infinite dilutions were also evaluated. The partial molar volumes of transfer (ΔVϕ0) and partial molar isentropic compression of transfer (ΔKϕ,s0) of AG from aqueous to aqueous FR solutions have been calculated and interpreted in terms of solute-co-solute interactions. Pair and triplet interaction coefficients have also been calculated. The results have been used to investigate the solute–solute and solute–solvent interactions as well as the effect of the concentration of FR on these interactions. It is observed that there exist strong solute–solvent interactions in these systems. The data of transfer parameters suggest that the type of interactions present in these systems are complex depending both on the nature of side group as well as on temperature.

Ion association constants of ionic liquids, 1-hexyl-3-methylimidazolium halide, in aqueous d-fructose solutions

In this paper, the interactions of 1-hexyl-3-methylimidazolium halides ([HMIm]Cl and [HMIm]Br) with aqueous d-fructose solutions have been studied by using conductance properties. Limiting molar conductivity (Λ0), association constant (KA) and distance parameter (R) were calculated using low concentration Chemical Model (lcCM) at temperatures ranges of (298.15–328.15)K and concentrations (0.05, 0.10 and 0.20)molkg−1 of d-fructose solutions. The Λ0 values increase with increasing temperature and decrease during the addition of d-fructose. The greater values of association constant for [HMIm]Cl relative to [HMIm]Br is due to the high surface charge density of the Cl− anion proposing strong association tendency with [HMIm]+ cation. Moreover, an enhancement was observed in the KA values as temperature is increased suggesting that ion-pair formation is an endothermic process. The mobility of ions was found to be completely controlled by the bulk viscosity (η) and consequently the Walden products (Λ0η) were estimated and discussed. The association constants were used to study the thermodynamic of association process. Consequently, Gibbs free energy (ΔGA0), enthalpy (ΔHA0) and entropy (ΔSA0) of ion-pair formation have been obtained at different temperatures. It was observed that the ion-association process exhibits a negative value of ΔGA0 and becomes more negative with increasing temperature proposing the spontaneity and feasibility of the association at high temperatures.

Di-d-fructose Dianhydride-Enriched Caramels: Effect on Colon Microbiota, Inflammation, and Tissue Damage in Trinitrobenzenesulfonic Acid-Induced Colitic Rats

In the present study we describe the preparation and chemical characterization of a caramel with a high (70%) content of difructose dianhydrides (DFAs) and glycosylated derivatives (DFAs). This product was obtained by thermal activation (90 degrees C) of highly concentrated (90% w/v) aqueous D-fructose solutions using the sulfonic acid ion-exchange resin Lewatit S2328 as caramelization catalyst. DFAs represent a unique family of cyclic fructans with prebiotic properties already present in low proportions (<15%) in commercial caramel. We report the antiinflammatory activity of the new DFA-enriched caramel in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis, an experimental model that resembles human inflammatory bowel disease (IBD), and compare its effects with those obtained with a commercial sucrose caramel and with linear fructooligosaccharides (FOS). For this purpose, the effects on colon tissue damage, gut microbiota, short-chain fatty acid (SCFAs) production, and different inflammatory markers were evaluated. The administration of DFA-enriched caramel to colitic rats showed intestinal antiinflammatory effect, as evidenced macroscopically by a significant reduction in the extent of the colonic damage induced by TNBS. This effect was similar to that obtained with FOS in the same experimental settings, whereas commercial caramel was devoid of any significant antiinflammatory effect. The beneficial effect was associated with the inhibition of the colonic levels of the proinflammatory cytokines, tumor necrosis factor alpha (TNF alpha) and interleukin 1beta (IL-1beta), and the reduction in colonic myeloperoxidase (MPO) activity and inducible nitric oxide synthase (iNOS) expression. The DFA-enriched caramel also promoted a more favorable intestinal microbiota, increasing lactobacilli and bifidobacteria counts as well as inducing higher concentrations of SCFAs in the luminal colonic contents. These results reinforce the concept of DFAs and glycosyl-DFAs as dietary beneficial compounds with prebiotic properties and suggest that the novel DFA-enriched caramel here reported may be an interesting candidate to be explored for the dietary treatment of human IBD.

Mutarotation of d-fructose in aqueous-ethanolic solutions and its influence on crystallisation

The mutarotation of d-fructose in aqueous-ethanolic solutions was studied between 24 and 50 °C. The ethanol:water mass ratios of the solvent were 3:1, 6:1, and 9:1. The principal tautomers found in the solution were β- d-fructopyranose. β- d-fructofuranose, and α- d-fructofuranose, as is found with aqueous solutions of d-fructose. The furanose tautomers were more strongly favoured in the aqueous-ethanolic solutions, comprising approximately 60% of the fructose in solution for the range of solvent conditions studied, in comparison to 27% in aqueous solution at 24 °C. The rate of mutarotation from β- d-fructopyranose to the furanose tautomers was fivefold slower in solutions of ethanol:water ratio of 9:1 than in aqueous solutions. The tautomeric composition of d-fructose in aqueous-ethanolic solutions was shown to affect the crystallisation of the sugar, due to the slow rate of mutarotation of furanose forms to β- d-fructopyranose.

Electrokinetic studies on cholesterol-carbohydrate systems

The hydrodynamic and electro-osmotic transport of water and aqueous solutions of d-fructose, d-glucose, sucrose, and urea through cholesterol-coated membrane has been investigated. The results have been examined from the viewpoint of non-equilibrium thermodynamics. Zeta potentials have been estimated in order to characterize the membrane-permeant interface.

Electrokinetic studies on carbohydrates

Measurements of hydrodynamic and electro-osmotic permeability through Pyrex sinter, using aqueous solutions of d-fructose, d-glucose, sucrose, and urea, have been made. The data were analyzed by using the non-equilibrium thermo-dynamics of irreversible processes. Electrokinetic potentials were calculated, in order to characterize the membrane-permeant interface

Laser-raman study of solute-solvent interactions in aqueous solutions of d-fructose, d-glucose, and sucrose

The solute-solvent interactions of d-fructose, d-glucose, and sucrose in aqueous solution were studied by comparison of characteristic, Raman of the water and the sugar components. Shifts in frequency and intensity were observed in both the bending and the stretching regions of CH 2 and H 2O. The ratios of integrated, Raman intensities I(CH 2)/I(H 2O) of the CH 2 peak and the H 2O bending band, and I(CH)/I(OH) of the C-H stretching line to O-H stretching band were determined. Their evolutions in terms of mass-concentration display discontinuities at specific concentrations for each of the three sugars. These breaks were interpreted as changes in the hydrogen bonding of the various species.