Increasing Health Benefit of Wild Yam (Dioscorea hispida) Tuber by Red Mold (Angkak) Fermentation

Abstract

Detoxification of cyanogen is very important in cyanide containing tubers such as wild yam (Dioscorea hispida). Principally, cyanogen detoxification is by converting cyanogenic glycoside into acetone cyanohydrin and further converted into free HCN that is easily removed by heating or soaking. Conversion of cyanogenic glycoside into free HCN is catalyzed by beta glucosidase enzyme (linamarase) in linamarin deglycosilation and a- hydroxyinitril liase (HNL) in acetone cyanohydrin degradation into free HCN and acetone. Endogen linamarase is found in the tubers and exogenous linamarase might be from microbes. It is supposed that fermentation of wild yam by angkak will reduce cyanide level. Angkak or Red Mold Rice (RMR) is a product of rice fermentation using Monascus sp mainly M. purpureus. Beside red pigment, angkak fermentation also produces a variety of secondary metabolites such as lovastatin, mevinolin, and citrinin. Monacolin K (lovastatin) from Monascus purpureus is an inhibitor for HMG-CoA reductase in cholesterol biosynthesis. Monacolin K production is higher in Dioscorea substrate compared to rice. RMD (Red Mold Dioscorea) reveals higher anti-cholesterol activity and anti-hypertension than red mold rice. RMD also exhibits antioxidant, anti-diabetic, anti-obesity, and induces cancer sell apoptosis and does not reveal mutagenic and toxicity. In RMD, monascin and ankaflavin have a role in reducing cholesterol. It is expected that wild yam fermentation by angkak will reduce cyanide level and produce health beneficial secondary metabolites.