Natural deep eutectic solvents (NADES) offer new opportunities for applications in different and distinct industries. They can be applied in the food, biomedical and pharmaceutical field. NADES are defined as a mixture of two or more components of natural origin, such as sugars, carboxylic acids, alcohols and amino acids. At specific molar ratios there is a high melting point depression of the mixture when compared with the pure components. In most cases, these systems are liquids at room temperature.
Industrial applications of NADES are very promising nevertheless, it is necessary to characterize these systems experimentally before models are developed to predict their properties.
In this work, viscosity and conductivity in the temperature range of 293.15 K to 338.15 K, were determined for Lactic acid: Betaine (2:1); Lactic acid: Histidine (9:1); Malic acid: Betaine: H2O (1:2:3) and Malic acid: Betaine: Proline: H2O (1:1:1:2) at these specific molar ratios. The flow activation energy (Eη) and activation energy for electrical conduction (Eσ) were calculated as described by the logarithm form of the Arrhenius equation, for viscosity and conductivity, respectively. The molar heat capacities of the above NADES were determined using a differential scanning calorimeter at temperatures from 293.15 K to 363.15 K and the vaporization enthalpies at 298.15 K were determined by thermogravimetric analysis.