THIS AGRICULTURAL JOURNAL 201 



Dairying in Ausfraiia. 



THE HON. F. II. MOOR'S IMl'RESyiONS. 



{CunHnued.) 



THE following is a further instalment 

 of the pamphlet ; — 



PASTEURIZING. 

 In order to understand the pasteuriz- 

 ing system of treating milk or cream for 

 butter-making purposes, it is necessary to 

 have a knowledge of the composition of 

 milk and its relation to bacteria. Milk is 

 a complex food, and is composed princi- 

 pally of water, fat, caseine, sugar and 

 ash, in the following average propor- 



tions : — • 



Water 86.80 



Fat 3.70 



Caseine and albumen 3.75 



Sugar 5.00 



Ash 0.75 



Two great objects are sought in the 

 pasteurizing of milk or cream. The iirs,t 

 is to drive off the obnoxious gases that 

 are present in milk produced from certain 

 fodders, such as rape, lucerne, &c. Such 

 milk has a strong, undesirable odour, 

 usually termed as "cowy." It has been 

 found that by proper aeration this fault 

 is easily got rid of, but for some reason 

 or other the farmer has not taken to aera- 

 tion. 



In order to be effective, the aeration of 

 milk must be carried out at a high rate 

 of temperature after coming from the 

 cow and before the undesirable element 

 becomes fixed in the milk. Since the 

 milk producer has not undertaken this 

 easy precaution in regard to the welfare 

 of his milk supply for butter-making, it 

 i=i therefore compulsory to effect the' 

 desired object at a later period — that is, 

 when it reaches the creamery or factory. 

 As the milk generally arrives compara- 

 tively, cold at the creameries, it is not pos- 

 sile to get the objectionable volatile ele- 

 ments liberated without raising the tem- 

 perature. It is found that the pasteuriz- 

 ing of the milk and the later exposure of 



on the cooler to the atmosphere ef- 

 fected the object sought for by aeration. 



As a matter of fact it appears that 

 greater good has been achieved from 

 this point of view than from a bacterial 

 standpoint. All the experiments so far 

 conducted prove that the greatest success 

 in improvement of quality is noticeal)le 

 only in districts that produce milk off of 

 rich artificial grass pastures. It is still 

 doubtful whether pasteurization will 

 effect any improvement in butter made 

 under good conditions from milk pro- 

 duced on clean hard pastures. 



The second object looked for is to kill 

 all the active micro-organisms that de- 

 velop in the milk after it leaves the cow. 

 Hitherto this has been the only con- 

 sideration dwelt upon by scientists. It is 

 well known that the milk in the udder 

 of a healthy cow contains no bacteria. 

 Many experiments have proved con- 

 clusively that such is a fact, and that all 

 the changes that subsequently take place 

 in the milk are due to the growth of bac- 

 teria. In ordinary dairying it is impos- 

 sible to take milk from the cow without 

 bringing a certain amount of bacteria 

 with it into the bucket. Their pre-encc 

 is universal. They are in the air, in dust, 

 in the soil, and in the water. Their 

 chief function is to break up substances 

 or bodies for the use of livins: animals 

 or plants. Under favourable conditions 

 bacteria multiply at an eiioiuious rate. 

 Milk is an excellent medium for their 

 propagation. 



Usually a certain class of l)acteria acts 

 upon the milk-sugar and converts it into 

 lactic acid ; this acid gives the sour taste 

 and thickens the milk. This is looked 

 upon by the milk producer as prejudicial, 

 and yet the butter-maker, in order to 

 bring about the changes necessary in the 

 cream before making good butter, has to 

 make overtures to and encourao-e the 

 same class of bacteria bv supplving the 

 requisite conditions for "their develop- 

 ment. The results in the past were very 

 uncertain owing to the want of know- 



