SOY AXD RELATED FERMENTATIONS. 13 
PEANUT PRESS CAKE KOJI. 
A sample of commercial peanut press cake, with a water content 
of 8.6 per cent, contained 50,000 bacteria per gram. These bacteria 
were predominantly of the Bacillus subtilis and B. mesentericus 
groups (2). Three thousand grams of this cake cooked in 2,000 
cubic centimeters of water for 50 minutes at 15 pounds pressure 5 was 
not sterile. The container used was a crock and the material was 
undoubtedly deep enough to prevent sterilization in such a container. 
When held" overnight at room temperature (24° to 26° C.) this 
cooked cake became viscid, and smelled of ammonia. 
Three parts of the peanut press cake was steamed in two parts of 
water for one-half hour. There was no excess of water. The wet 
cake was placed on a huck towel 6 in a wire basket, to a depth of 
1-J inches, when treated with steam. A wet huck towel also covered 
the cake to prevent superficial drying. This material was autoclaved 
for one hour at 15 pounds pressure. No bacteria survived, as shown 
by the sterile cultures. 
This last procedure was repeated with the following variation. 
The cake was heaped in the wire trays instead of being spread evenly 
in the tray. The bacterial count at 37° C. for 24 hours was 100 
bacteria per gram. This last lot of peanut press cake 7 was mixed 
with 900 grams of roasted and ground wheat. Its further treatment 
was that already outlined. 
The experiment was completely set up at 3 p. m. of April 1. On 
April 2 at 1.30 p. m. there was a delicate growth of mold, a very 
slight local viscosity (due to bacteria) near the wood of the trays, 
and a sweet nutty odor. At 3 p. m. further mold growth and a 
warmth to the material were noted. At 3.35 p. m. one (1) tray was 
hot (35° C), two (2 and 3) were warm (30° C), and the last (4) 
was becoming hot (31.5° C). The temperature of the compartment 
was 27° C. The contents of trays 1 and 3 were viscid to slightly 
viscid. Tray 4 contained excellent koji from all external appearances. 
The growth of mold had caked the material. This peanut press cake 
koji was mature in less than 48 hours. The temperature of tray 1 at 
5.30 p. m. of April 3 was 41.5° C. Its contents were slightly viscid, 
drying out, and gave a positive test for ammonia with fuming 
hydrochloric acid. The mold had grown throughout with a yellow 
color against the wood of the tray, and the bacterial count was 
100,000,000 bacteria per gram. The material in trays 2 and 3 ran 
an approximate bacterial count of 700,000,000 bacteria per gram. 
The temperature of tray 4 at 9.30 a. m. of April 3 was a little more 
than 35° C. and the contents were yellow throughout from the 
fruiting of the mold, and not viscid. This was the best appearing 
tray. It showed little evidence of ammonia. Both its mold count 
and bacterial count were slightly lower than those of the others, being 
30,000,000 molds and 88,000,000 bacteria per gram. 
In these laboratory experiments a count of 300,000,000 or over 
per gram for bacteria in shoyu-koji was directly parallel to the 
5 Fifteen minutes were required for the autoclave to run up to 15 pounds pressure and 
20 minutes for it to run down. The total period of cooking was therefore 85 minutes. 
9 A towel was used because the mesh of the basket was too large for pieces of cake. 
7 Prepared for koji by being ground into strings one-half inch in diameter by a food 
chopper driven by an electric motor. 
30S35— 23 3 
