Search results for "Hydrophobic effect"

Interactions between flavor compounds and food ingredients and their influence on flavor perception

2002

Interactions between flavor compounds and food ingredients are reviewed and their influence on flavor perception is discussed. Proteins are known to bind flavor compounds. For β-lactoglobulin, the most-studied example, hydrophobic interactions with volatiles are described. The effect of the medium on the conformation of the protein and its ability to bind flavor compounds is discussed. In general, the retention of volatiles by protein is much lower than that by fat. In emulsions, however, the presence of protein at the oil/water interface induces a significant effect on flavor release and flavor perception of hydrophobic flavor compounds. For starch, an extensively studied hydrocolloid, amy…

Modeling Supramolecular Polymerization: The Role of Steric Effects and Hydrophobic Interactions

2019

We present a combined experimental–simulation study of self-assembly into one-dimensional filaments. Experimentally, we study amphiphilic AuI-metallopeptides in neutral aqueous media. Our model foc...

Molecular surface area and hydrophobic effect.

1992

Capillary electrophoretic and nuclear magnetic resonance studies of interactions between halophenols and ionic liquid or tetraalkylammonium cations.

2003

Aqueous capillary electrophoretic studies were performed to investigate interactions between halophenols and 1-ethyl-3-methylimidazolium tetrafluoroborate or tetraethylammonium tetrafluoroborate electrolytes. In both cases, increased halogen size correlated with increased affinity for the electrolyte cation. For isomers, the ortho substituted isomer exhibited higher affinity than the para isomer. Irreproducible CE results for analyte pairs in the presence of the ionic liquid stimulated investigations of the interactions between halophenols as well as with the cations of the electrolyte. These interactions were explored by proton and fluorine one-dimensional NMR. The NMR results indicated di…

Influence of aroma compounds on the mechanical properties of pectin gels.

2004

A detailed study of the rheological behavior of pectin gels, in the presence of aroma compounds in food concentration is reported. In high methoxylated pectin (HMP) gels, it has not yet been shown if aroma compounds can be responsible for modifications in rheology. Two rheological techniques were used to measure the impact of aroma substances on rheological properties of HMP-based systems. Maximum strain to fracture (sigma F) was compared between flavored and unflavored gels on stress-displacement curve, which was obtained with uniaxial compression until fracture. An oscillatory rheometer was applied to determine the gelation time (Tgel). It appeared that all the aroma compounds studied inc…

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

2018

New calixarene-based nanosponges (CaNSs), i.e., hyper-reticulated polymers constituted by calixarene monomer units joined by means of bis(1,2,3-trialzolyl)alkyl linkers, were synthesized, characterized and subjected to preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network was assessed by means of FTIR and 13C{1H} CP-MAS solid-state NMR techniques, whereas morphological characterization was provided by SEM microghaphy. The materials were pro…

Influence of Anion and Cation Structure of Ionic Liquids on Carboxylic Acids Extraction

2019

A recently proposed new mechanism and a model of reactive extraction of carboxylic acids by hydrophobic ionic liquids (ILs) was tested on five systems from published as well as from new equilibrium data on liquid-liquid extraction of butyric and lactic acids (BA and LA) from aqueous solutions. Two phosphonium and one ammonium ILs were used. The model describes experimental data for all systems with a good fit. The mechanism of acid extraction by ILs is very similar for all tested systems. This indicates a more general validity of the developed model. The model allows deeper understanding of regularities in carboxylic acid extraction by hydrophobic ILs. Stability constants of the first acid-…

Continuum-uniform approach calculations of the solubility of hydrocarbons in water

1993

Abstract The ransfer free energies from gas phase to water for some hydrocarbons are calculated by means of a continuum-uniform model of the solvent. For the calculation of the cavitation energy a model based on the surface tension is proposed. The calculated values are compared with the experimental free energies obtained with and without a corrective factor that accounts for the difference in the solute—solvent sizes. Good agreement between the theoretical free energies and the corrected experimental data is obtained. Our calculations seem to show that the hydrophobic effect is directly related to the molecular surface area.

Introduction to the microsymposium and on the modulation of thermodynamic parameters relative to biomolecule-solvent interactions

1980

Abstract As a result of introducing a macromolecule in a solvent, changes in the structures of both solute and solvent are generally found. In this specific meaning we refer here to ‘relaxation phenomena’. The discussion will either concern or keep in a view the case of biomolecules and to which extent these changes are involved in their thermodynamic stability or functional structure: Dr. Ben-Naim will discuss hydrophobic interactions and structural changes in the solvent; Dr. Wen will focus on thermodynamic properties of aqueous solutions on hydrophobic solutes; Dr. Cordone, Dr. Fornili and myself shall discuss results of experiments concerning solutes on several types(proteins, polynucle…

Solution properties of polyelectrolytes XII. Semi-quantitative approach to mixed electrostatic and hydrophobic polymer-gel interactions

1996

Abstract Aqueous size-exclusion chromatography of polyanions, where secondary effects affect the total separation mechanism, was investigated. For elution of polyelectrolytes on inorganic silica-based supports, the electrostatic polymer-gel repulsive interactions were evaluated through the values for a hypothetical repulsion layer, X e , according to the model developed by other workers. Using a similar procedure, the existence of an effective barrier defined as X e − X h is proposed for those systems in which electrostatic repulsion and hydrophobic interactions take place simultaneously as secondary mechanisms. X h can be viewed as a measure of the “enlargement” of the geometrical pore rad…