Acceleration of lactose hydrolysis using beta-galactosidase and deep eutectic solvents.

A series of new deep eutectic solvents based on choline levulinate and various hydrogen bond donors were prepared and characterized by1H NMR, FT-IR, TG, and DSC. In particular, their physicochemical properties (density, viscosity, conductivity, and thermal stability) were determined and their usability as an enhancing additive to the enzymatic reaction mixture, for the enzyme was checked. It has been shown, that prepared DES, exhibits low viscosity (at 40 °C within the range 0.1-0.8 Pa·s), high thermal stability (in almost all cases above 150 °C), and density within the range 1.1-1.17 g cm-3. Also, it has been shown, that obtained mixtures can stabilize the enzymes, and positively influence on its activity. The addition of up to 15% (v/v) of DES mixture composed of choline levulinate: ethylene glycol, enhanced more than threefold lactose hydrolysis yield by ß-galactosidase. The present study shows the relevance of the newly designed DES series for improving enzymes properties with the potential to apply in the effective conversion of food processing origin substrates.