Utilization of strawberry and raspberry waste for the extraction of bioactive compounds by deep eutectic solvents

Deep eutectic solvents were used for the recovery of bioactive compounds from strawberry and raspberry by-products. The best performing eutectic solvent (DES-7) was compared to one organic solvent. Total and individual phenolics, sugars, uronic acid, anthocyanins and the antioxidant activity in vitro were measured. The highest yield and purity of phenolic compounds in the extracts were obtained from strawberry extrudate with acetone (11.5%) and from raspberry extrudate (36.7%) with DES-7. The greatest yields of total sugars and acid sugars were achieved from raspberry extrudate using acetone and from strawberry extrudate using DES-7, 82.23 and 1.88 mg/g of extract, respectively. DES-7 was the solvent that extracted the most anthocyanins (1.28 mg/100 mg of extract). In addition, the extracts obtained with acetone presented the best values of antioxidant activity in vitro (DPPH value of 5.33 mmol TE/kg fresh weight and ORAC value of 37.89 μmol TE/g fresh weight) the extracts obtained with DES-7 also presented an interesting antioxidant activity, and a promising solvent for the extraction of bioactive compounds.