2011 Volume 106 Issue 1 Pages 50-57
Cis and trans rose oxides（rose oxide） detected in sweet potato shochu were 0.8 ~ 4.6μg/L and 0.3~ 1.9μg/L, respectively. The aroma threshold value of rose oxide in a 25% ethanol solution and sweet potato shochu was 0.35μg/L and 14μg/L, respectively. The aroma of rose oxide was evaluated as a sweet, floral, and rose-like flavor. Rose oxide was not included in a first moromi-mash and a sweet potato. Linalool, nerol, geraniol, and α -terpineol were not converted to rose oxide though citronellol was in the modelmoromi (pH4.2, 15% alcohol) incubated for five days at 30°C .The distillation process and the pH 3.5 orless in the model moromi promoted conversion from citronellol to rose oxide. It was found that koji moldand Saccharomyces cerevisiae were not able to convert citronellol to rose oxide. The bioconversion of citronellolfrom geraniol was not koji mold but S. cerevisiae. Our results indicated that citronellol bioconvertedfrom geraniol by S. cerevisiae during the fermentation process was further converted to rose oxide byan acid-catalyzed reaction. Also, we confirmed that this chemical conversion was promoted by distillation.
