Abstract: At present,the process between rhizome grinding and diosgenin hydrolysis is generally called "fermentation".Fermentation strongly influences the extraction efficiency of diosgenin,but the mechanism is unknown.Experiments were designed to verify whether the process was a true fermentation process by microbe or a biochemical reaction process(s) of the rhizomes when they were crashed.The results showed that the process(s) was a very complex biochemical process(s) catalyzed by the endo-enzyme(s) only when the rhizome tissue were damaged,and meant that the principle of the so called fermentation was in fact the transformation of secondary metabolite when the plant suffered environment stress(es).Based on this result,the processing parameters were optimized according to the factors that affected the biochemical reactions.With these new parameters,the processing time was significantly shortened from 72 hours to 12 hours,and the final yielding rate of diosgenin was as high as 0.8%,which was 11% higher than that of the old method.At the same time,changes of pH were only observed during traditional fermentation process,but not observed during new process,indicating that the dioscin transformation did not accompany with the production of H⁺.

Key words: diosgenin, fermentation mechanism, optimization of fermentation conditions