Deep eutectic solvents improve the biorefinery of alperujo by extraction of bioactive molecules in combination with industrial thermal treatments

Abstract Thermal treatments are the latest developments in the olive oil biorefinery industry to extract bioactive compounds from its by-products, mainly the alperujo. To reach these goals and reduce energy consumption the utilization of deep eutectic solvents has been studied. An initial screening led to define a eutectic mix of choline chloride, glycolic and oxalic acid (DES9) as one of the adequate solvents to increase the solubilization of phenols and sugars, with a temperature reduction from 180 °C to 120 °C. DES9 increased the concentration of acid sugars by six times and the concentration of hydroxytyrosol by 30 times, to up to 85.81 mg/g of dry matter. The activity of DES9 is not due to the activity of each component separately or to the mixture of the two acids, but to the eutectic mixture of all of them. In the future, these solvents could improve the extraction, stability and bioavailability of bioactive compounds and the biorefinery of alperujo.