Translational Diffusion Coefficients of Volatile Compounds in Various Aqueous Solutions at Low and Subzero Temperatures

Abstract

Translational diffusion coefficients (D(12)) of volatile compounds were measured in model media with the profile concentration method. The influence of sample temperature (from 25 to -10 degrees C) was studied on translational diffusion in sucrose or maltodextrin solutions at various concentrations. Results show that diffusivity of volatile compounds in sucrose solutions is controlled by temperature, molecule size, and the viscosity of the liquid phase as expected with the Stokes-Einstein equation; moreover, physicochemical interactions between volatile compounds and the medium are determinant for diffusion estimation. At negative temperature, the winding path induced by an ice crystal content of >70% lowered volatile compound diffusion. On the contrary, no influence on translational diffusion coefficients was observed for lower ice content.

Contribution of Molecular Pathways in the Micellar Solubilization of Monodisperse Emulsion Droplets

“…Equation 2 predicts an inverse dependence of flux on viscosity μ through the contribution of D w , the diffusion coefficient of the oil molecule in aqueous solution. The Stokes−Einstein or Wilke−Chang equation predicts that D w ∼ μ -1 , a prediction confirmed experimentally for sucrose solutions . The resulting dependence of flux on μ -1/2 likely accounts for the strong effect of sucrose addition on the solubilization kinetics exhibited in Figures −7.…”

“…Thus, in the present research, the effect of viscosity was investigated using sucrose in monodisperse alkane-in-water emulsions that were gradually solubilized in an aqueous micellar solution. As a low-molecular-weight compound, sucrose has the ability to retard the movement in water of the transferring solute in its molecular form . By using a nearly monodisperse emulsion, the rate at which the size of the oil droplet diminishes could be monitored, and combined with turbidity measurements to provide two approaches to measure the solubilization rate.…”

Tensiometry as a Simple Analytical Method for Quantification of Solubility and Release of Aroma Molecules in Aqueous Media

“…While the quasi-equilibrium surface tension of monoterpene alcohols is more or less invariant to the molecular structure and solution temperature/presence of salt, as follows from the strong deviations in the saturation time, the diffusion and adsorption activity is clearly dependent on the molecular and environmental features. These observations are in agreement with the earlier studies, which emphasized the importance of molecular mobility (translational diffusion and mass transfer through phases) of volatile compounds on their release from the matrix [29].…”

1,2-Dichlorobenzene affects the formation of the phosphoenzyme stage during the catalytic cycle of the Ca2+-ATPase from sarcoplasmic reticulum

“…Temperature is another important factor that could potentially affect this transition, as it has been demonstrated that at 21 °C the E 1 P to E 2 P isomerization is rapidly affected at high KCl concentrations [ 71 ]. Temperature is also important for compound solubility in aqueous solutions, as it has been shown that the solubility of aroma compounds (such as methyl ketones, ethyl esters, aldehyde and alcohol) decreases when incubated on ice as the concentration of the compound is increased, which could contribute to explain the effect of temperature and DCB solubility at 0 and 25 °C in the EP measurements [ 72 ].…”