SOY AND RELATED FERMENTATIONS, 
The usual Japanese koji room (fig. 2) is 32^ feet long, 11 feet wide, 
and 7 feet high. Its walls are thick, and in the more modern fac- 
tories are built of brick, which does away with fluctuations in the 
temperature from without. At one end of the room is an entrance 
and at the opposite end a window (fig. 3). In the ceiling several 
openings provide means of escape for the carbon dioxid and the 
damp air. Steam pipes along the floor make it possible to warm 
the room in cold weather. The ceiling is built with many layers of 
straw in order that the condensing moisture may be absorbed. One 
disadvantage of such a ceiling is that infection always occurs in the 
wet straw. A large area of infection directly over the piles of 
koji trays is detrimental to the production of sweet koji. In modern 
buildings, therefore, the surface of the ceiling is coated with cement. 
When a cement ceiling is used the condensed water drops on the 
trays of koji. which also is harmful. 
The koji room is naturally always well inoculated with the spores 
of the mold used in making the koji for shojm. The presence of 
these green Aspergillus spores is not detrimental unless the growth 
of the tane-koji alone is desired for the koji. The koji room may 
also become infected with other troublesome fungi. Insects, too, 
occasionally overrun the room. The burning of sulphur is useful in 
combating any infection of a koji room. 
The fermentation or brining, which produces the moromi, is car- 
ried on in crocks or wooden vessels of any kind, such as tubs, barrels, 
or vats (PL I). According to Takahashi, the inside of wooden re- 
ceptacles may be painted, paraffined, or even pitched, without injury 
to the mash. 
Fig. 3. — Japanese koji room (interior). 
