Mij2, 1920.] Agricultural Gazette of N.S.W. 493 



same vat. When subsequently investigating the cause of this, it was found 

 when a bacteriological plate was made from a sample taken from the first 

 few gallons of cream as it left the machine, that the species of undesirable 

 bacteria found in the cream before pasteurisation had started were present 

 in undiminished numbers. Further bacteriological plates made from samples 

 of the remainder of this lot of cream after pasteurisation showed freedom 

 from these bacteria ; and on further investigation being made, it was found 

 that the cream (about 1 gallon) which had lodged in the outlet pipe of the 

 machine had not been sutiiciently pasteurised through not having come in 

 contact with the heating coil of piping, while the cream in the body of the 

 vat had been heated and kept at the required temperature for the stipulated 

 period. The greatest care should be taken to ensure that the ci'eam which 

 has lodged in the outlet pipe of the machine is removed and mixed with 

 the heated ci-eam in the vat, when the temperature of the bulk is well over 

 140 degrees. 



Again, the cream may have been properly pasteurised, but been contam- 

 inated after leaving the pasteuriser. To obviate this trouble, care should be 

 taken when using the flash system to heat as nearly as possible the whole 

 bulk of cream to the required temperature of 180 degrees to 185 degrees. 

 To enable this to be done the Depaitment recommends the use of a movable 

 pipe attachment to the outlet pipe of the m3,chine, so that any cream which 

 the thermometer shows has not been heated to the required temperature 

 when the pasteuriser is first started can be run direct into some receptacle 

 and afterwards returned to the main bulk of cream to be treated. 



With the batch system, care should be taken that the cream, when it has 

 been heated to 145 degrees to 150 degrees, is held at that temperature for 

 twenty minutes to half an hour before cooling is commenced. If this is not 

 done the main object of using low temperatures in the heating to destroy the 

 bacteria is defeated, for comparatively few undesirable organisms are killed 

 at these low temperatures unless held there for some time. 



Again, as before stated, even when the methods of pasteurisation have been 

 correctly carried out, the cream maj' have been contaminated after being 

 heated, by dirty pipes, coolers^ vats, churns, &.C., and the fishy flavour in 

 the butter produced in this manner. Admitting that pasteurisation and 

 neutralisation of cream is an undoubted remedy for fishiness in butter, it 

 cannot be contended that the fact relieves the farmer of his responsibility 

 to supjjly a clean untainted cream to the factory ; nor should it make the 

 factory manager any the less careful in keeping clean everything that the 

 cream touches, for, although tishiness in butter may be eradicated by careful 

 pasteurisation, there are other infections in cream caused by contact 

 with dirt which are just as injurious to the butter made from such cream, 

 and which are not eliminated by this process. Therefore it behoves everyone 

 connected with the factory, be he supplier or employee, to make cleanliness 

 the first principle underlying all he does, either in connection witir the 

 production of cream on the farm or in the process of its manufacture into 

 butter at the factory. 



