The Formation of β-Damascenone in Sweet Potato Shochu

Abstract

The formation of -damascenone during shochu manufacture was investigated by quantifying -damascenone at each stage of manufacturing. Steamed sweet potato has a low level of free damascenone (0.02-0.1 g/g). During fermentation, -damascenone was produced in small quantities that were degraded by yeast. Thus, the second mash accumulates little free -damascenone (approximately 17 g/L). The concentration profile in the fractionated distillate showed that -damascenone was produced during heating. Most -damascenone in shochu was formed during distillation, not during steam heating and fermentation. It is suggested that the level of -damascenone in shochu could be increased by reducing the pH of the second mash and prolonging the distillation period. Sweet potato cultivars differed in total free and hydrolyzed -damascenone content and there was a strong association between each cultivar and its shochu damascenone content. The selection of the sweet potato cultivar is important for determining the quantity of -damascenone in a shochu brew.