Exploration of interactions between L-aspartic acid and saccharides in aqueous medium at T = (293.15–313.15) K: Physicochemical and spectroscopic approach

Abstract

In this study, we report the density, viscosity, taste behavior and UV– Vis spectrophotometry results of L-Aspartic acid (Asp) in aqueous solutions of L-arabinose and D-xylose over an integral composition regime (2.0 wt%, 2.5 wt%, and 3.0 wt%) at atmospheric pressure (P = 101 kPa) and at temperature ranges of (293.15, 298.15, 303.15, 308.15, and 313.15) K. The various densimetric and rheological parameters such as apparent molar volume (Vϕ), apparent molar volume at infinite dilution (Vϕ0), apparent molar isobaric expansion at infinite dilution (Eϕ0), Hepler’s constant (∂2VΦ0/∂T2)P, relative viscosity (ηr), viscosity coefficients (BJandAF), Gibbs free energy of activation of viscous flow of solvent and solute (Δμ1#,0andΔμ2#,0respectively), and corresponding change in enthalpy ΔH2#,0, entropy ΔS2#,0, apparent molar volume of transfer at infinite dilution (Vɸ,tr0) viscosity B-coefficients of transfer (BJ,tr), interaction coefficients (using the McMillan-Mayer theory), dB/dT and solvation number (Sn) have been calculated using the experimentally collected physical characteristic data (density and viscosity). Variation of these parameters with concentration and temperature were analyzed in the light of ion-ion, ion–dipole and ion-hydrophilic interactions between solute (L-Aspartic acid)-cosolute (L-arabinose and D-xylose) in aqueous medium. An effort has also been made to compare the taste behaviours of the amino acid in water and in an aqueous solution of saccharides, as the taste behaviour is separated into four basic taste qualities in distinct ranges. To access different common intermolecular interactions in the systems under consideration, the cosphere overlap model has also been used. A detailed evaluation of the results from the thermodynamic and physicochemical parameters shows that Asp acts as a structure builder when L-arabinose/D-xylose is present. The preservation of effective ionic interactions in the studied systems was further confirmed by UV spectral analysis.