Studies on the Fermentation Control of Sake Mash (VX)

Sake Brewing with α-Koji

Abstract

Sake brewing with the koji prepared from pregelatinized rice (ce-rice) was studied.
1) When the yeast mash of the reformed type (“yamahai-moto”) was prepared from α-koji with high activity of alkaline protease, the production of F-N was much increased. The amount of glycine, alanine, methionine, isoleucine, leucine, phenylalanine, threonine, and glutamic acid were much larger as compared with ordinary process.
2) The amount of sake cake was decreased, and sensorily good sake was obtained by the use of α-koji, in which amylase activity was enhanced by treatment with Mg. It seemed necessary to decrease slightly the koji ratio than usual, because the use of a-koji showed a tendency to increase F-N and acidity.
3) A strain of Aspergillus having high amylase, protease, and catechol-oxidizing activities were found, and named 0-strain. The koji prepared with the strain had very high tendency of browing. The of use the α-koji prepared with the strain gave high velocities in saccharification and alcohol production. The mash colored brown, and the cake became black. The ITT value of produced sake was extremely low.
On the other hand, when α-koji was prepared with water containing 0.01 M Fe and Mn, the mash did not give black cake, inspite of high catechol-oxidizing activity and browning tendency of the koji.