2017 Volume 112 Issue 6 Pages 432-441
In our previous study, a process in a laboratory scale was developed to produce rice shochu rich in ethyl caproate, ethyl lactate, and isoamyl acetate（flavor-rich rice shochu）. In this study, a pilot scale using a 127 L second-stage fermenter was carried out, with the addition of material rice of 25 kg（koji ratio, 33%; water ratio, 165%）, caproic acid producing bacteria（CAPB）consortium, and lactic acid bacterium（LAB）on the first day of the second-stage fermentation. An ethanol concentration of 130 g/l was achieved on the 7th day of the second-stage fermentation; this then slowly increased and finally reached 142 g/l. With the addition of CAPB consortium and LAB, ethyl caproate and ethyl lactate were produced during the second-stage fermentation and increased with time. The final fermented mash was subjected to vacuum distillation, and a relatively high ethyl caproate recovery efficiency of 325.3% was obtained, which was consistent with the result of the laboratory scale. Odor activity values（OAV）of the flavor compounds were calculated using the flavor compounds contents and their olfactory thresholds, and flavor characteristics of rice shochu with/without the addition of CAPB consortium and LAB were evaluated. The traditional rice shochu generally has a banana flavor, while the flavor-rich rice shochu has the Chinese Luzhou-flavor. The flavor-rich rice shochu has flavors of banana and apple, as well as an acid solution odor. However, the acid solution odor was so light that it did not significantly influence the fruit flavor. This study demonstrated that it is possible to produce flavor-rich rice shochu in a pilot scale.
