6 BULLETIN 1152, U. S. DEPARTMENT OF AGRICULTURE. 
MATERIAL. 
A yellow, round soy bean, such as the Yellow Mammoth variety, 
was selected as preferable for soy sauce, because it is rich in oil and 
in protein and has practically no starch. 
An eastern-grown American wheat, the Stoner variety, which is 
rich in starch, was chosen by the Office of Cereal Investigations of 
the Bureau of Plant Industry as a variety close to that used in Japan. 
Only pure clean water should be used for soaking the beans and in 
making the brine. A biologically impure water, one contaminated 
with sewage organisms or factory waste, should not be used. The 
obnoxious bacteria in sewage-contaminated water become active 
readily in the beans during soaking and may disturb the growth of 
the mold ferment in the early part of the fermentation, later pro- 
ducing bad effects or off-flavor in the mash. 
The mold ferment employed in shoyu-koji manufacture is Asper- 
gillus flavus Link, occasionally A. oryzae (Ahlb.) Cohn. or strains 
intermediate between the two species (%4). A mixture of several 
strains is frequently found in the tane-koji. The particular tane- 
koji used in the laboratory experiments was a strain (Bureau of 
Chemistry No. 4272.2) of the A. -flavus group grown on rice grains 
and similar in morphology to Bureau of Chemistry No. 10S, 4 a strain 
of A. -flavus. 
Commercial, not chemically pure, salt was used for the moromi. 
According to Japanese' authority, experimental work has been suc- 
cessful with purified sodium chlorid only occasionally and commer- 
cial practice never. Foreign substances other than basic salts of 
calcium and magnesium, often found in even a fair grade of bulk 
commercial salt, will not interfere with shoyu making. This manu- 
facturing process, like all others, however, should be conducted 
under sanitary conditions. Sea salt is used as a rule in Japan. 
Certain Japanese manufacturers add cultures of pure yeast be- 
longing to the genus Zj-gosaeeharomyces {23) at the time of* placing 
the first mold-fermented material in the brine. 
PREPARATION OF INGREDIENTS. 
, 
In preparing shoyu-koji the soy beans are soaked in running 
water for about 20 hours (fig. 4) and then cooked until they are 
rather soft. Unless the water is changed during the soaking a rapid 
fermentation, due to spore-forming rods, occurs. These bacilli as 
spores are on the beans as they come from the field. Beans soaked 
in unchanged water become warm, even hot, and sour at the bottom 
of a mass 5 to 6 inches deep in two or three hours at 22° C. (72 D F.). 
Such beans, even after autoclaving, are sour to the taste. It is the 
customary factory practice in Japan to soak the beans with changes 
of water at intervals of several hours. In laboratory experimenta- 
tion beans were placed in running water for 20 hours and cooked 
on the following day. The hours used as an illustration here may 
be changed to conform to factory working hours. The intervals 
given, however, should not be changed beyond reason. 
4 Obtained from former Centralstelle fiir I'ilzkulturen. a collection now in the custody 
of Dr. Johanna Westerdijk. Phytopathologisch Laboratorium, Willie Commelin Scholten, 
Javalaan, Baarn, Holland. 
