Development of a process for producing ethyl caproate- and ethyl lactate-rich rice shochu

Abstract

To increase the popularity of rice shochu, a process was developed to produce ethyl caproate- and ethyl lactate-rich rice shochu. On a laboratory-scale, there was a shochu production trial with Saccharomyces cerevisiae Y-E. Caproic acid added in the second-stage fermentation was esterified to ethyl caproate. Both ethyl caproate and ethyl lactate were produced by adding a caproic acid-producing bacterial (CAPB) consortium and lactic acid bacterium (LAB) to the shochu production process. Yellow koji was more appropriate for producing a flavour-rich shochu with the addition of a CAPB consortium and LAB than white koji. Optimal addition time for the CAPB consortium and LAB was on the first day of the second-stage fermentation, judging from concentrations of ethyl caproate and ethyl lactate produced. Additional dosages of CAPB consortium and LAB positively affected the formation of ethyl caproate and ethyl lactate, respectively. Shochu production with the addition of 2% and 4% CAPB consortium led to ethyl caproate concentrations of 27.3mg/L and 47.9mg/L in genshu, respectively, and the shochu achieved the best sensory test score from the Japanese shochu brewery panellists.