96 Dairy Bacteriology. 



Wei) of Holland is added to milk in the manufacture of 

 Edam cheese, apparently serving the same purpose as the 

 addition of the pure culture starter in cheddar cheese 

 making. In Norway, a sour, slimy milk (taettemjolk) 

 is used as food. It is produced by the addition of some 

 previously fermented milk. This beverage is also used 

 in some of the Norwegian settlements of Wisconsin, the 

 original seed having been brought from Norway, and the 

 bacteria maintained by constant propagation from one 

 sample of milk to another. The milk has the odor and 

 taste of butter milk, but is not especially appetizing in 

 appearance to any one not accustomed to it ; it is, how- 

 ever, as harmless to health as is any other form of sour 

 milk. It is not known that any of these forms of slimy 

 milk are distinctly harmful to the quality of butter or 

 cheese. 



Alcoholic fermentation of milk. The bacteria as a 

 class are incapable of producing alcohol in' appreciable 

 amounts. The alcoholic beverages, beer, wine, and cider, 

 are produced by the growth of yeast, in such sugar 1 

 containing liquids as fruit juices, extracts of grains, etc. 

 The common types of yeasts are incapable of acting on 

 milk sugar, but they can ferment glucose, maltose, and 

 cane sugar, forming equal amounts of alcohol and car- 

 bonic acid gas, which causes the effervescence of fer- 

 mented and carbonated drinks. There are, however, some- 

 types of yeasts found in milk and its products that are 

 able to ferment milk sugar. 



All yeasts grow best in an acid medium, hence those 

 fermenting milk sugar find suitable conditions for growth 

 in sour milk or whey. They may at times become of 

 economic importance in the cheese industry, because of 

 the contamination of the milk with large numbers of 



