Cream and Factory By -Products. 125 



result is that they become a foul, stinking mass in hot 

 weather. This material is usually carried home in the 

 same set of cans in which the milk is brought and as the 

 cans are often insufficiently cleaned, the new milk is in- 

 fected with undesirable organisms. That such a custom 

 should have grown up in the Swiss cheese industry, where 

 on account of the sweet curd nature of the cheese, all 

 possible precautions should be taken to insure the best 

 quality of milk, illustrates the necessity of bacteriologi- 

 cal principles being thoroughly instilled into the dairy 

 industry. 



123. Preserving- factory by-products. Factory by- 

 products on account of their chemical constitution and 

 their bacterial flora soon decompose, and a considerable 

 proportion of the nutrients are lost. This has led to the 

 introduction in some factories of measures that tend to 

 prolong the keeping quality of the whey and skim-milk, 

 although the value of these products do not warrant much 

 expense. The conditions under which skim-milk and 

 whey are produced facilitate the rapid development of 

 bacteria. The continued fermentation of these materials 

 may be inhibited in part as follows : 



1. Quick cooling to a temperature unfavorable for 

 germ development. 



2. Pasteurizing or scalding. 



Where fed immediately, it is hardly worth while to 

 treat these by-products, as they will remain sweet for 

 several hours. In some factories the skim-milk is heated 

 by introducing live steam. Where milk is pasteurized 

 for butter- making, the keeping quality of the skim-milk 

 is increased 24-48 hours thereby. 



124. Skim-milk a distributor of disease. In some 

 countries, notably in Denmark and Germany, tubercu- 

 losis is so common among cattle that skim-milk from 



