232 CREAM-RIPENING AND STARTERS 



the starterline, as high as possible in hot water, say up to about 

 200 F. The sample may assume a cooked taste, but this will 

 soon disappear after the starter has been carried on a few 

 days. The milk should be left at this high temperature for 

 about ten or fifteen minutes. A longer time does no harm. 

 Then the milk is gradually cooled to about 80 F. This high 

 temperature is desirable, because the germs present in the 

 commercial culture may be somewhat dormant. This high 

 temperature would tend to revive them more quickly than a 

 lower temperature. Great care should always be taken to 

 cool the milk previous to inoculating it with the pure culture, 

 otherwise the germs present in the culture will be destroyed. 



Inoculation. The next step is to inoculate the "prepared 

 milk with the culture obtained from the laboratory. The 

 bottle which contains the culture is carefully opened, turned 

 over and emptied into the pasteurized milk. It should be 

 held down closely to the mouth of the jar containing the 

 sterile milk, in order to prevent, as far as possible, the entrance 

 of the air and the consequent danger of contamination. Then 

 the milk containing the culture is thoroughly stirred and set 

 away in a room where the temperature is about 70 F. This 

 will gradually cool the milk from 80 to 70 F., and in about 

 twenty to forty hours the milk will sour and coagulate. Germs 

 in nearly all of the liquid cultures are rather slow in acting upon 

 the milk, undoubtedly due to the dormancy of the germs, and to a 

 comparatively few of them being present in the culture. When 

 the powdered cultures are used, a little more care is essential to 

 get the powder thoroughly mingled with the milk. It is a trifle 

 more difficult to get the powder thoroughly mixed with the milk 

 than it is to get the liquid cultures mixed. If anything is used 

 with which to stir the sample, it should be sterilized before com- 

 ing in contact with the milk. This applies in the preparation of 

 all cultures. In testing or sampling the mother-starter, nothing 

 should be allowed to come in contact with it unless it has pre- 

 viously been thoroughly sterilized. The powder cultures are 

 usually more vigorous in their effect than most of the liquid 

 cultures now on the market. The powder cultures usually 



