Green production of diosgenin from Discorea nipponica Makino tubers based on pressurized biphase acid hydrolysis via response surface methodology optimization

ABSTRACT In this study, a novel strategy was established to produce diosgenin from Discorea nipponica Makino tubers, in which pressurized biphase acid hydrolysis and Soxhlet extraction of total saponins were incorporated for the first time. The hydrolysis conditions were optimized by response surface methodology after the preliminary investigation on affecting factors by single-factor experiments and L16(45) orthogonal experiments. Under the optimal conditions, namely dioscin (eq. 8？g of the DNM tubers) was hydrolyzed in a biphase system composed of 50？mL of 6？μL/mL H2SO4 solution and 50？mL of petroleum ether (90–120°C) at 140°C for 2？h, the highest yield of diosgenin has been achieved at 1.87%, that was 85.1% higher than the conventional method while the H2SO4 consumption reduced by 92.5%. The results demonstrated that the newly developed approach was more effective and cleaner, and promising value-added technology for the extraction of diosgenin from DNM tubers in industrial application. GRAPHICAL ABSTRAC