130 SAMPLING MILK AND CREAM 



The reason why sampling every second, third, fourth or fifth 

 day, gave more accurate results than composite sampling" must 

 be attributed to the fact that in the intermittent sampling the 

 sample was transferred from the weigh can direct into the test 

 bottle. The portion used for testing, therefore, was bound to be 

 representative of the milk from which it was taken, there could 

 be no question of inaccuracy due to separation of fat. In the 

 composite samples, on the other hand, the cream was separated 

 out and in spite of the most painstaking efforts to thoroughly mix 

 the cream back into the remainder of the composite sample, the 

 portion transferred to the test bottle was of more or less un- 

 certain composition. This was the case with and without heating 

 the sample before the transfer was made. This investigation 

 was made in the month of November under most favorable con- 

 ditions for preserving composite samples. Had it been made 

 in the month of June, at a time when most of the cows are fresh 

 in milk and the milk contains predominatingly large fat globules 

 and when the temperature on the receiving platform where the 

 samples usually are kept is very high, the separation of cream 

 in the sample jar would have been even more complete, the 

 layer of cream would have been drier and tougher and less 

 miscible and the results of the tests of the composite samples 

 would probably have been still more unfavorable. 



Sampling of Cream. Correct sampling of cream is vastly 

 more difficult than correct sampling of milk. This is largely 

 due to the fact that the cream usually is older and often lumpy 

 and mixes into a homogeneous consistency with difficulty only. 

 It is also due to its richness in butterfat. Average cream con- 

 tains approximately 10 times as much fat as milk. The possible 

 error caused by lack of uniformity in consistency, therefore, is 

 greatly augmented. 



Composite samples of cream representing portions of succes- 

 sive shipments or deliveries from the same patrons are practically 

 out of the question and cannot be too strongly condemned. It is 

 difficult to take small aliquot portions of cream and the tendency 

 of cream samples to lose part of their moisture by evaporation, 

 upon remaining for several days on the shelves of the warm re- 

 ceiving room, causes such samples to yield excessively high and 



