JOURNAL OF THE BREWING SOCIETY OF JAPAN

Show abstractHide abstract

Effects of glutaminase in rice koji and a salt-resistant glutaminase from Bacillus subtilis GT strain on miso fermentation were investigated and following results were obtained.
1. Glutaminase activity in ordinary rice koji was 30% as high as that of soy sauce koji. A high correlation was recognized between the activity and the growth of koji mold, though the activity was rather weak.
2. It appeared that the glutaminase in rice koji hardly took part in the production of glutamic acid during miso fermentation.
3. Glutamine and glutamic acid were assumed to be liberated in almost the same amounts from soybean protein by protease and peptidase.
4. The production of glutamic acid was increased 1. 5 to 1.6 times by adding 0.1 to 0.5 g of the glutaminase preparation from B. subtilis GT per 1 kg of miso at the beginning of fermentation.
5. Glutaminase in rice koji was greatly inactivated during miso fermentation, whereas glutaminase from B. subtilis GT was relatively stable.
6. As a result of a sensory evaluation, the majority of panelists pointed out increased “Umami”(good taste) in the miso by the addition of the glutaminase preparation.

View full abstract

Download PDF (2146K)

Contribution of β-glucosidase activity (BGA) in shochu making was studied. BGA of black koji (A. awamori) was higher than that of white koji (A. kawachii), and that of yellow koji (A. oryzae) was lower than that of white koji. BGA of white koji was rapidly increased in the last stage of koji making. BGA of white koji made by low temperature process was higher than that made by high temperature prosess. A sweet potato shochu of a light type was produced in brewing test by using commercially available enzyme which contained little BGA.

View full abstract

For the purpose of obtaining a yeast strain which accumulates a large amount of L-lysine in molasses medium, a 2-aminoethylcysteine-resistant mutant, KY 5545, was hybridized with the haploid, YOY 50, derived from a baking strain. Spore clones isolated from this diploid were mated each other, and one of the strain, YOY 783, was selected. YOY 783 accumulated about 6% of Llysine in the cells on dry matter basis when cultured in the molasses medium, whereas it accumulated only a small amount comparable to that of its parental strains when cultured in YPD medium.

View full abstract

Register with J-STAGE for free!