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 

 others 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. 



Cheese 

 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 



39 a 



39 a 



39 a 



39 a 



IS 



I S 



I S 



IS 



I S 



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 



.66 

 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 



■ cent. 

 1 



1.2 

 .9 

 1.1 

 1.2 

 1.1 

 1.4 

 1.0 

 .5 

 .5 

 .5 

 .8 

 .5 

 .5 

 .6 

 .6 

 .5 

 .5 

 .4 

 .6 

 .5 

 .3 

 .5 

 .5 

 .5 

 .4 

 .5 

 .4 

 .1 



Nogas 



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. 



Do. 

 Gassy. 



Do. 

 Very gassy. 



Do. 

 Gassy. 

 Very gassy. 



Do. 

 Gassy. 

 Very gassy. 

 Gassy. 

 Slightly 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 



