Solution properties and taste behavior of lactose monohydrate in aqueous ascorbic acid solutions at different temperatures: Volumetric and rheological approach

The densities and viscosities of lactose monohydrate in aqueous ascorbic acid solutions with several molal concentrations m = (0.00-0.08) mol kg−1 of ascorbic acid were determined at T = (298.15-318.15) K and pressure p = 101 kPa. Using experimental data apparent molar volume (ϕV), standard partial molar volume (ϕV0), the slope (SV∗), apparent specific volumes (ϕVsp), standard isobaric partial molar expansibility (ϕE0) and its temperature dependence (∂ϕE0/∂T)P, the viscosity B-coefficient and solvation number (Sn) were determined. Viscosity B-coefficients were further employed to obtain the free energies of activation of viscous flow per mole of the solvents (Δμ10≠) and of the solute (Δμ20≠). Effects of molality, solute structure and temperature and taste behavior were analyzed in terms of solute-solute and solute-solvent interactions; results revealed that the solutions are characterized predominantly by solute-solvent interactions and lactose monohydrate behaves as a long-range structure maker.