Bioactive compounds extraction from malted quinoa using water-ethanol mixtures under subcritical conditions

The extraction of bioactive compounds from malted quinoa flour using different water/ethanol mixtures under subcritical conditions was performed, and two mathematical models to describe the extraction kinetics were compared. The variables evaluated were extraction temperature, solvent mass flow rate and solvent composition, and the best conditions were selected using a screening design. The extract with the highest antioxidant activity with 95% inhibition of DPPH, 2084 mg GAE/100 g flour of total phenol content (TPC), and 2029 mg QCE/100 g flour of total flavonoid content (TFC) was obtained at 200 °C, 2.5 g/min and 25% ethanol. For these conditions, the two-site kinetic model had a better fit. When comparing these results with conventional extraction techniques, the extraction yield and antioxidant capacity enhanced. Hence this technique results promising since it also allows to obtain extracts with an antioxidant activity similar to commercial antioxidants. •Subcritical extracts from malted quinoa were obtained.•All variables studied had a great influence on the extraction.•The two-site kinetic model fitted better when predicting antioxidants extraction.•A significantly high antioxidant activity was observed in the optimal extract.•Malted quinoa extracts could improve oxidative stability of food products.