PASTEURISATION OF MILK FOR CHEDDAR CHEESE-MAKING., 287 
The experiments of C. W. Brown and K. Peiser® indicate 
that the heat death-point for the B. coli-cerogenes group 
is raised 14°4° F. by whole milk. In view of this factor in 
killing the harmful gas-formers, it is satisfactory to note 
that no typical colonies of this critical group in cheese 
manufacture developed on whey agar plates containing 
1/10 c.c. of the pasteurised milk. 
Mohler? and others have shown that B. tuberculosis can 
survive the raw milk process of cheese manufacture, and 
Mohler is reported to state that a generalised case of 
tuberculosis was produced in a guinea pig by an inoculation 
of B. tuberculosis obtained from cheese seven months old. 
With an acidity (expressed as lactic acid) not greatly in 
excess of °25% it is doubtful if this temperature of 165° F, 
used regeneratively will kill all cells of B. tuberculosis 
present in the milk. Were there definite evidence of the 
killing out of the tubercular bacilli by this process, the 
public health aspect would somewhat strengthen the case 
for the pasteurisation of milk for cheese-making. The 
demand for dairy products free from living cells of B. 
tuberculosis is a feature of steady growth. Williams and 
Harries® state that on the evidence then (1915) available, 
from 1/4 to 1/3 of human tubercular disease, other than 
that of the lungs, is due to the ‘“‘cow”’ type. 
College Experiments. 
These experiments included trials of pasteurisation by 
the flash method at 155°, 165° and 175° F. and the holding 
process for thirty minutes at 145° F. This latter process 
was the most bactericidally efficient (99°947%); the flash . 
methods at the two higher temperatures were satisfactory 
averaging 99°89. 
During the cheese-making process petri dish cultures 
were made from the milk before and after pasteurisation, 
from the raw and pasteurised milks at renneting, and from 
