432 Agricultural Gazette of N.S.W. [June 2, 1920. 



estimate of the acidity of a large quantity of cream makes a difference in the 

 -amount of neutraliser to be added, while one-twentieth of 1 per, cent, 

 variation in 600 gallons of cream would make a difference of about 3 lb. in 

 the amount of soda that would have to be used to reduce the acidity 

 from per cent, to '2 per cent. Over-neutralising, whatever the kind 

 of neutralising agent used, is mostly caused by this looseness or want of 

 method. One of the most important aids to the advancercent of the quality 

 of our dairy products would be the better scientific training of those working 

 at the factories, enabling them to have a thorough insight into laboratory 

 methods and to realise the absolute importance of being exact in every detail 

 and of leaving nothing to chance, 



In connection with the pasteurisation of cream as carried out in Xew 

 South Wales, the importance of ascertaining with accuracy the temperatures 

 to which the cream is heated cannot be too strongly emphasised. No 

 thermometer should he used unless it has previously been checked for correct 

 reading. Unfortunately there has been on the market a class of dairy 

 thermometer, samples of which when tested have been found to be inaccurate 

 and as much as 10 degrees " out." Such an error in temperature would mean 

 the difierence between making a good or bad keeping butter, or between a 

 «ood or bad flavour even in that freshly made. This overheating of cream 

 is a frequent cause of inferior butter being marketed, although in some cases 

 the flavour arising from it has been attributed to over-neutralising. 



The investigational work commenced in 1914 by the Department has been 

 carried on from time to time by the Chemist's and Dairy Branches, and the 

 results have been made available to those interested as sooq as possible. The 

 investigations now under discussion were commenced by Mr. Ramsay in 

 October, 1918, at the request of the Dairy Branch, and the factory work was 

 brought to a close in February, 1919. The results were written up by the 

 following May, but publication has been delayed by various circumstances. 

 They now appear in the form of this Science Bulletin. 



Results of Experiments in Brief. 



The results obtained at the different factories visited, where methods of 

 neutralising and pasteurising were dissimilar, varied considei'ably ; this was 

 es})ecially noticeable where different sized pasteurisers of the "holding" type 

 were used. In such cases neutralisation was found to be irregular and faulty 

 where the vats were filled to cover the heating coil by several (in some cases 

 8 or more) inches of cream, and where there was a large space between the coil 

 and the sides and bottom of the holding vat. In these machines the coils 

 are of practically uniform diameter, irrespective of the breadth or depth of 

 the vat into which they are fitted. It was found that the most eSicient 

 mixing of neutralising agent and cream was effected in the 500-gallon 

 sizes, where tlie coil fitted close to the walls and bottom and where the cream 

 did not quite reach to the top of the coil or barely covered it. 



Complete and, quick mixing is essential to good results — and this holds 

 good whether lime or soda is used, and under either the flash or holding 



