Extraction Of Diosgenin From Dioscorea Zingiberensis C.H. Wright With Mortierella Elongata PFY Fermentation

Saponin is the main raw material for the synthesis of steroid hormone drugs and contraceptives, but the pollution has become a major obstacle to the development of diosgenin industry during its production. The traditional production technology of diosgenin produced a plenty of acidic waste water and waste residue, which caused serious environmental pollution. This study focused on reducing high concentrations of organic waste water and waste generated during the production to achieve the green production of diosgenin. The main contents are as follows:A new production technology of diosgenin was developed through the degradation of turmeric cellulose by using the Mortierella elongate PFY, forming the enzymolysis/ fermentation-acid hydrolysis combined method. The production of 1 g diosgenin just needed 8.6mL 37% concentrated hydrochloric acid by this method, and the yield improved 13.23% compared to the pre-fermentation-acid hydrolysis method.The Dioscorea zingiberensis C.H. Wright (DZW) raw material after the removal of starch was fermented by PFY. Fermentation conditions were studied, and the substrate residual rate was taken as index. The results showed that the optimum fermentation conditions of strains was under 30 ℃, initial pH value of 5, fermentation time of 10 days, substrate concentration of 100g/L, shaking speed of 150 r/min and 2% inoculum. After the pre-treatment, the remaining solid was only 10% of the starting DZW powder.Diosgenin loss was then investigated, which happened in each treatment process such as amylase saccharification, acid hydrolysis and cellulase treatment. Through the comparison of the cellulase degradation effect with hydrolysis/fermentation-acid hydrolysis combined method, a possible mechanism for the degradation of turmeric cellulose by PFY fermentation was proposed.The acid hydrolysis conditions and extraction conditions in the new technology were optimized. Taking the diosgenin yield as an index, the optimum acid hydrolysis condition was solid mass (g):acid addition (mL)=1:5, hydrochloric acid concentration of 2 mol/L, acid hydrolysis time of 4 h. A second acid extraction of the solid residues could improve the diosgenin yield of 8.5%, and the optimum extraction time was 12 h. A second extraction after sonication could also improve the diosgenin yield of 6.8%.