Characteristic flavor of Kansho-shochu (sweet potato spirit).

Abstract

Kansho-shochu flavor (KSF) was found in the neutral fraction and was eluted by hexane-ethyl acetate (9:1) from a silica gel column. There were several monoterpene alcohols such as linalool, α-terpineol, citronellol, nerol and geraniol in the KSF. These monoterpene alcohols contributed to the sensory property of KSF. On the other hand, there were glycosidically bound geraniol and nerol in steamed sweet potatoes. In a model system of shochu mash, geraniol and nerol were transformed into linalool and α-terpineol through heat treatment and into citronellol by the shochu yeast. These results suggest that the monoterpene alcohol glycosides in steamed sweet potatoes were hydrolyzed by glycosidic enzymes in the shiro-koji of shochu mash. Subsequent transformation of the liberated nerol and geraniol into linalool and α-terpineol by the steam distillation process was also indicated.