IV. A FULL ACCOUNT OF THE PREPARATION 



OF BACILLUS ACIDOPHILUS MILK FOR 



HUMAN CONSUMPTION, AND OF 



ITS KNOWN PROPERTIES 



Much time and effort have been given in recent years to the pro- 

 duction of sour milk and sour milk products. Milk soured with B. 

 bulgaricus powders or tablets and special preparations sold as koumiss 

 have gained wide usage, especially in this country. Irrespective of the 

 alleged therapeutic properties from the standpoint of bacterial im- 

 plantation in the intestine, these preparations are of undoubted merit. 

 They are a valuable food and serve as a substitute for ordinary milk 

 for which many persons have little or no tolerance and which to many 

 others is objectionable as such. Furthermore, these sour milk products, 

 when they have been prepared successfully, are beverages which have 

 attained considerable popularity. 



Bacillus acidophilus milk bears some resemblances to sour milk pre- 

 pared with pure cultures of B. bulgaricus or with bulgaricus powders 

 or tablets. Coagulation of the casein takes place in both, due to acid 

 production, and no gas is produced. There is an absence also of other 

 products of the ordinary putrefactive type. Both are distinctly acid 

 to the taste, and unless the B. bulgaricus milk has been incubated too 

 long, they are palatable. 



The two products differ in the following respects. The acidophilus 

 milk never attains the degree of acidity in old culture as does the bul- 

 garicus milk ; in fact there is little or no danger of the former becoming 

 too sour if the time of incubation is within reasonable range, which 

 cannot be said of the other product. The acidophilus milk acquires a 

 creamy, but never sticky or stringy, consistency, while the bulgaricus 

 milk has a thicker and at times a more or less slimy character, depend- 

 ing largely, of course, on the particular strains of B. bulgaricus 

 employed in the preparation. The acidophilus milk has a decidedly 

 perceptible aroma and taste, which add very materially to its palata- 

 bility and which are more or less absent from the bulgaricus milk. 



The following method is employed in the preparation of the Bacillus 

 acidophilus milk. 



Sweet skimmed milk is sterilized by autoclaving at an extra pressure 



