SOUR AND COAGULATED MILK 123 



the churned fat before sampling. If the butter has been churned 

 into a few large lumps, these lumps can be taken out in a pan, or 

 pail, with a comparatively small amount of milk, and this 

 heated until the butter has melted. This is then remixed with the 

 milk from which it was first taken and sampled while it is being 

 stirred. 



The churning of the milk during transit is mainly due to 

 two things: First, to a high temperature of the milk (65 to 

 85 F.) and second, to hauling partly filled cans a long distance 

 over rough roads. If the temperature of the milk is low (about 

 50 F.), when it leaves the producer, there is seldom any danger 

 of having churned milk at the creamery. 



Frozen Milk. When milk is cooled to 31 F., or below, it 

 freezes. Ice forms near the sides and bottom of the can, until 

 a funnel-shaped cavity filled with milk is left in the center. 

 According to both Richmond and Fleischmann, the icy por- 

 tion contains more water than the unfrozen milk, and the 

 unfrozen portion is rich in solids. According to Farrington, 

 when 25 per cent of the sample of milk was frozen, the icy 

 portion contained about i per cent less fat than the original 

 portion. When about half of it was frozen there was no great 

 difference in the fat-content of the frozen and unfrozen parts. 



In practice, however, freezing seems to have a different effect. 

 When a can full of partly frozen milk is sampled at the creamery, 

 the unfrozen milk nearly always contains less fat than the original 

 sample. This can be accounted for by opening the can of milk 

 and noting the amount of frozen cream on the sides near the top. 

 Whether the unfrozen portion contains less or more fat than the 

 original depends, therefore, upon conditions. At any rate, 

 frozen milk has a composition different from that of the original 

 sample. On this account an accurate sample cannot be had, 

 unless the frozen portion be first completely melted and well 

 mixed with the remainder. 



Sour and Coagulated Milk. In order to get a fair sample 

 from a can of sour and coagulated milk, it must be stirred 

 very thoroughly, so as to bring the coagulated milk into a 

 uniform emulsion. A better sample can usually be obtained 



