480 ALCOHOLIC FERMENTATION OF MILK 



kefir or kafyr granules, which are used in the Orient to prepare an 

 alcoholic beverage from milk, contain both bacteria and yeast cells. 

 The cause of the fermentation of the alcoholic beverage, known as 

 kumys, prepared in Siberia from mare's milk and ass's milk, is not 

 known. 



In addition to the bacteria, saccharomyces and torula, higher 

 moulds (i. e., those forming a true mycelium) are likewise found in 

 milk. Among such moulds may be mentioned Oidium lactis, Peni- 

 cillium glaucum, Penicillium roqueforti, Penicillium camemberti, and 

 Mucor racemosus. Many of these moulds play an important role 

 in the ripening and flavoring of cheese. 



QUESTIONS. 



1. Is it possible in practice to obtain germ-free milk from the cow in larger 

 amounts? If not, why not? 



2. What measures are necessary to keep the bacterial content of milk as low 

 as possible? 



3. What is the most important source of increase of the bacterial contents 

 of milk. ? 



4. What should be the maximum of dirt permissible in milk? 



5. What brings about the souring of milk? What change occurs in lactose 

 or sugar of milk in the process of souring? 



6. What is meant by a stereo-isomenc body? 



7. What is meant by dextrogyr lactic acid? What is meant by sinistrogyr 

 lactic acid? 



8. What is polarized light? 



9. Where are the lactic acid bacteria found? 



10. Describe in general terms the four groups of lactic-acid bacteria. 



11. Name some of the various types belonging to each of the four groups. 



12. What are the morphologic features of the most common types of lactic 

 acid bacteria? 



13. What is meant by the coli-aerogenes bacteria? 



14. What are the anaerobic bacteria found in milk? 



15. What are the four groups of butyric acid formers? 



16. What is a clostridium? 



17. Describe some of the butyric-acid formers. 



18. What peptonizing bacteria commonly occur in milk? 



19. Describe the Bacillus subtilis. 



20. Describe the Bacillus mesentericus vulgatus. 



21. Name and describe some of the chromogenic bacteria found in milk. 



22. Name some organisms producing alcohol in milk. 



