Effects of liming on the flavor of kokuto-shochu, a spirit made from non-centrifugal sugar

Abstract

Kokuto-shochu is a traditional Japanese spirit prepared from kokuto, a non-centrifugal brown cane sugar. When manufacturing kokuto, lime is added to the sugarcane juice to accelerate the crystallization of sucrose. Although the liming process differs depending on the manufacturer, the effects of liming on the quality of kokuto-shochu are unclear. Therefore, we investigated the flavor characteristics and volatiles present in kokuto-shochu prepared from kokuto with different liming degrees. Kokuto-shochu prepared from kokuto without liming had a pronounced kokuto-like flavor with a rich taste and contained higher contents of nerolidol, nonanal, acetoin, β-damascenone, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone compared to that prepared from kokuto with liming. On the other hand, kokuto-shochu prepared from kokuto with excess liming had a comparative grassy flavor. It contained higher esters, 4-vinylguaiacol, and pyrazines compared to other shochu. The levels nerolidol, isoamyl acetate, nonanal, and acetoin were affected by the mash pH during fermentation, and thus, liming would affect the formation of such volatiles via changing the mash pH. In contrast, pyrazines, 4-vinylguaiacol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were not affected by mash pH, and their levels in the kokuto-shochu were consistent with those in kokuto raw materials. These results suggested that the liming process affects the levels of volatiles in kokuto-shochu by changing the mash pH and volatile levels in kokuto raw materials.