6 
BULLETIN 148, U. S. DEPARTMENT OF AGRICULTURE. 
few additional tests were made with Bacillus ~bulgaricus starter, 
using fresh cow manure for contamination, and with cheese 31. 
Table 1, enough manure was added to the milk to give it a slight 
color. The result of this test, in which culture W was used, is seen 
in Plate I, which illustrates the efficiency of this starter on gas-pro- 
ducing bacteria. This test was perhaps no more severe than many 
ethers that were made. The two cheeses were cut 24 hours after 
making from the same lot of badly contaminated milk. The upper 
cheese shows the effect of the starter; the lower cheese, made with- 
out starter, is badly "nissler." This experiment was not made to 
determine whether or not contaminated milk would make good cheese, 
but to test the effect of the starter on milk heavily inoculated with 
gas-producing bacteria. The cheese, as was to be expected, was not a 
normal cheese ; it had a strong, bitter taste, but abnormal gas forma- 
tion was entirely suppressed. 
Table 1. — Showing suppression of gas formation in Swiss cheese by the use of 
Bacillus bulgaricus cultures in normal amounts. 
No. 
Culture 
No. 
Starter. 
Amount. 
Acidity. 
Condition of cheese. 
Starter. 
No starter. 
39 a 
39 a 
39 a 
39 a 
39 a 
39 a 
39 a 
39 a 
IS 
IS 
IS 
IS 
IS 
44 H 
44 H 
44 H 
44 H 
44 H 
44 H 
44 i 
44 i 
' 44 i 
44 i 
44 i 
W 
Per cent. 
1 
1 
1 
1 
1 
1 
1 
1 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
1 
1 
1 
1 
1 
1 
1 
1.5 
1.5 
1.5 
.75 
1.5 
1.5 
2.0 
Per cent. 
1 
1.2 
.9 
1.1 
1.2 
1.1 
1.4 
1.0 
.5 
.5 
.5 
.8 
.5 
.5 
No gas 
do 
Slightly gassy. 
Edge gassy... 
No gas 
do 
....do 
....do 
....do 
....do 
....do 
Slightly gassy. 
Edge gassy... 
do 
....do 
No gas 
Slightly gassy. 
No gas 
....do 
....do 
....do 
....do 
....do 
Edge gassy... 
do 
Slightly gassy. 
No gas 
Edge gassy... 
No gas...." 
Very gassy. 
Do. 
Do. 
Do. 
Do. 
Gassy. 
Do. 
Very gassy. 
Gassy. 
Very gassv. 
Do. 
Gassy. 
Very gassy. 
Gassy. 
Slightlv gassv. 
Do". 
Gassy. 
Slightly gassy. 
Very gassy. 
Gassv. 
Do. 
Very gassy. 
Gassy. 
Do. 
Very gassy. 
Attention is called to cheeses 4, 15, 16, and IT, Table 1, where the 
outside surface or " edge " of the cheese to perhaps a half inch or 1 
inch was badly gassy, while the center was entirely free from gas. 
The outside portion becomes cooled, allowing the gas-producing 
bacteria to damage this part of the cheese, while the inside portion 
remains at a temperature more favorable for the growth of B. ~bul- 
garicus. This illustrates excellently the fact that the long-continued 
