Determination and study on refractive indices and viscosities of aqueous solutions of citric acid, (citric acid + glycerol), and (citric acid + d-sorbitol) at T = 293.15 K-323.15 K and atmospheric pressure.

Citric acid, glycerol, and d-sorbitol are used as important food additives. In this research work, viscosities and refractive indices (the physico-chemical properties) for aqueous solution of citric acid, as well as ternary solutions of (water + d-sorbitol + citric acid) and (water + glycerol + citric acid) were measured in mass fractions of citric acid (0.03-0.21) and at temperatures (T = 293.15, 303.15, 313.15, and 323.15) K and atmospheric pressure. For these solutions, the experimental refractive indices were fitted using a semi-empirical equation which its constant, Kr, was introduced by Koohyar in 2011. This constant can be applied to investigate the power of interactions between solute and solvent molecules in aqueous solutions. Also, the experimental viscosities were fitted by the Jones-Dole and Arrhenius-like equations. Obtained data of this research work can be applied in food industries.