July 2, 1920.] Agricultural Gazette of N.S.W. 485 



Dairy Produce Factory Premises and 

 Manufacturing Processes. 



The Application of Scientific Methods to their 



Examination. 



[Continued from page 337.] 



L. T. MacINNES, Dairy Expert, and H. H. RANDELL, A-ssistant to the Biologist. 



Example No. 3. 



The best butter of this factory, after being kept for any length of time in 

 cold storage, showed evident signs of deterioration, although up to a week or 

 two after being manufactured it was of choicest quality. 



Our investigation showed that the cream as churned was of choicest grade 

 and had been well pasteurised. The infection that was in the cream before 

 being heated, although large, had not had time to develop sufficiently to aflfect 

 the flavour. This latent contamination was practically wiped out by the 

 system of pasteurisation employed, as was shown by the reduction of the 

 number of colonies in 1 c.c. of cream from 1.50,997,000 before pasteurising to 

 only 500 after the heating process had been completed. After being held 

 for nineteen hours these increased to 13,400, a striking contrast to what was 

 experienced where a similar comparison was made in the investigations 

 described in Examples Nos. 1 and 2. The increases in the present case were 

 mainly due to normal increase and the multiplication of the spoi e-f ormers 

 undestroyed in pasteurising. The small increase in the number of colonies 

 after nineteen hours' retention of the cream in the closed-in batch -holder 

 demonstrates the advantages of this system of pasteurisation, as far as 

 reinfection from atmosphere and other outside influences is concerned. The 

 cream after being heated is not exposed again, except when in the fluming 

 while gravitating into the churn. This is an important consideration, 

 especially where factories are situated near dusty thoroughfares. 



The air exposures made in the churn room show that there was little 

 infection present in the atmosphere. This was to be expected, as the factory 

 in question is situated on the highlands of the Dividing Range. 



Air Exposures. 



Each dish was carefully exposed for two and a half or three minutes, being 

 carried about the room so that the plate was exposed in every part. The 

 cold room, as is usually the case, showed the presence of moulds in some 

 numbers ; spraying or fumigating with formalin would be of benefit. 

 Factory managers cannot keep too strict a watch on these rooms — mould is 

 so easily carried into them by the butter boxes, the timber of which is often 

 infected before it arrives at the factory. 



