38 Dairy Bacteriology. 



ual barrels which are supposed to be emptied each day. 

 As these barrels are, however, rarely ever cleaned from 

 the beginning to the end of the season, they become very 

 foul, and the whey placed in them from day to day highly 

 polluted. It is this material which is taken back to the 

 farms in the same set of cans that is used for the fresh 

 milk. When one recalls that the very best type of milk 

 is essential ,for the making of a prime quality of Swiss 

 cheese, and that to secure such, the maker insists that the 

 patron bring the product to the factory twice daily, the 

 before mentioned practice appears somewhat inconsist- 

 ent. 



Treatment of factory by-products. To overcome the 

 danger of infecting milk from factory by-products with 

 either undesirable fermentative organisms, or disease- 

 producing bacteria, the most feasible process is to de- 

 stroy these organisms by the application of heat. In 

 Denmark, some portions of Germany, and in some of the 

 states in this country, laws exist which require the heat- 

 ing of all skim milk before it is returned to the farm. 

 This is done by the direct use of exhaust steam, or run- 

 ning the product through heaters. 



The treatment of whey in cheese factory practice is 

 especially important since the warm whey must be stored 

 for a number of hours before it is returned to the farms. 

 Even under the best of conditions the whey is certain to 

 be in an advanced state of fermentation when placed in 

 the milk cans, and it only needs the infection of the whey 

 tank with harmful bacteria to cause great loss on ac- 

 count of the injury of the product by these bacteria. 

 Among Canadian factories the custom of heating the 

 whey as it passes from the cheese vat to whey tank has 

 been introduced, and where ever adopted has been re- 



