286 J. K. MURRAY. 
/ 
ment is uncommon under present Australian conditions, 
and to bring about their common observance would need 
years of educational work among farmers as well as regu- 
latory action under a Dairy or other Act. With average 
milk now reaching cheese factories, ‘‘ fast’’ batches and 
great losses by spoilage are commonplace in cheese made 
from raw milk. Pasteurisation prevents these conditions 
by killing out the vast majority of the Streptococcus lactis 
graup which are mainly responsible for ‘‘fast’’ batches, 
-and members of the Bacillus coli-cerogenes group which 
cause most spoilage. Inoculation of the pasteurised milk — 
‘with a good quality starter places subsequent fermentations 
‘under the control of the cheese maker. The problem is more 
complex than that associated with butter-making because 
of the critical nature of casein coagulation by rennet in the 
cheese-making process. This coagulating property of 
casein is affected by heating, and the ability of the coagulum 
to shrink and expel whey is also adversely affected by the 
degree of heat used in pasteurisation. Whereas tempera- 
tures of 200° Fah. and above have been and are used with 
success in the regenerative pasteurisation of cream for 
pbutter-making, experiments elsewhere,’ *and by Mr. T. H. 
Atkinson in this State, have shown that the most satis- 
_ factory temperature for the regenerative pasteurisation of 
milk for cheese-making is, under average factory conditions, 
about 165° Fah., higher temperatures causing considerable 
difficulty in the manufacturing process and giving an 
unsatisfactory product. 
College experiments conducted during 1921 with the 
then Cheese Expert, Mr. J. G. McMillan, and during the 
present year with Mr. Atkinson, have shown that the 
bactericidal efficiency of flash methods of pasteurisation at 
this temperature is satisfactory. The writer has not 
access to unpublished figures of Messrs. McMillan and 
Randell. 
