Revelation of mechanism for aqueous saponins content decrease during storage of Dioscorea zingiberensis C. H. Wright tubers: An essential prerequisite to ensure clean production of diosgenin

Abstract

Releasing saponins to aqueous phase from Dioscorea zingiberensis C. H. Wright tubers is an effective way to decrease water pollution in diosgenin industry. Aqueous saponins (AS) are unstable during storage and could be hydrolyzed under certain conditions. To preserve the maximum AS content, different storage methods were evaluated, and it was found that storage at −20 °C and storage after 80 °C drying could well maintain AS content stability. AS model solution system was then constructed and utilized to simulate storage process. Adding sodium dodecyl sulphate and boiling can both effectively ensure the stability of AS content, while acid shock deferred the decrease of AS content. AS content decreased after sequential effects of endogenous enzymes and microbial community from tubers in different phase during storage. Myroides, Enterococcus, Alcaligenes and Stenotrophomonas were enriched as storage proceeded. It was also concluded that multiple glycosidase and surfactants secreted by selectively enriched microbial community decreased AS content stability at late stage of storage. This study also provides a guideline for preventing the loss of glycoside bioactive constituents in other industrial crops during storage.