A newly developed rice-
shochu making process which reduces waste production and process cost has been studied.The low-waste process involved addition of the post-distillation slurry from the conventional method to
moromi. In our previous report we bred
shochu yeasts with high viability and selected from strain S 20 E 12.In this report, firstly, by using strain S 20 E 12 we examined various conditions for preparing post-distillation slurry suitable for the newly developed recycling process of
shochu making. It was found that suitable post-distillation slurry was derived from
moromi with more than 30% koji ratio and 8 to 10 days of second-stage fermentation period in the conventional method.The activity of saccharifying enzymes remained stable and viable cell number was high, being 4.7×10
7 cells/m
l after vacuum distillation at-63 cmHg and 45°C for four hours. On the basis of these results, we studied optimum conditions for the newly developed recycling process.
Moromi consisting of 138g steamed rice and 175m
l post-distillation slurry without addition of yeasts, rice-
koji, and water, was fermented at 25°C for 4 different fermentation periods.Viable cell number was 3.7×108 cells/m
l on the 8th day and 1.1×10
8 cells/m
l on the 15th day. But there was a rapid increase of sulfur compounds and α-amino compounds, especially in prolonged fermentation. Distillate of the
moromi showed increase of acetaldehyde concentration and decrease of flavor compound with longer fer mentation time.The results suggest that distillation on
moromi soon after completion of 8 day fermentation would make good quality
shochu by the newly developed recycling process.
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