TESTING OF MILK AND CREAM 91 



colostrum or beistings contain as high as 17*6 % 

 albumin, and this is why beistings turn thick 

 when boiled. 



Milk Sugar. 



This is present in milk to the extent of 

 5 %. In appearance it is like confectionery sugar, 

 but not so sweet. It is present in the form of 

 solution, and varies from 4-6 to 5-5 %. It 

 plays a very important part in the making of suc- 

 cessful creamery products indirectly, being the part 

 of clean milk from which the acid develops when it 

 is allowed to stand. When clean milk has a sour 

 taste it is the sugar which has been changed into 

 lactic acid. This is brought about by small organ- 

 isms known as lactic ferment or lactic bacteria. 

 These lactic germs feed on the milk sugar and 

 break it down", into simpler forms of sugar known as 

 grape and galactose, these being afterwards turned 

 into lactic acid. When the lactic germs get to work 

 in fresh milk the average acid test is about 0*2 %, 

 even when the milk has no taste of it. When 

 there is a distinctly sour taste the acid test is 

 about o'4 %, while the milk turns thick when 

 07 % has been reached. Milk very seldom 

 develops more than 2 % acidity or lactic acid 

 however long it stands ; this is because all the milk- 

 sugar has been consumed and lactic acid formed ; 

 the bacteria, having nothing further to work on, 

 remain dormant or decay. The lactic ferment is, 



