152 Dairy Bacteriology. 



water, allowed to dissolve as far as possible, and the mix- 

 ture heated and cooled. Either of these liquids will give 

 satisfactory starters; the cost however is high, and in 

 most places milk can be obtained more cheaply. The in- 

 oculation and the temperature should be so controlled, 

 as to ripen the starter at the time it is to be needed. 

 These conditions must be determined by the maker for 

 himself. It should be remembered that the bacteria 

 grow much more rapidly, as the temperature is in- 

 creased; and hence, the amount of inoculation is depend- 

 ent on the temperature at which the starter is to be kept, 



When the starter is propagated under practical con- 

 ditions, it sooner or later deteriorates, either in acid pro- 

 duction, or in flavor, and a new pure culture must be 

 procured from the manufacturer. It is impossible to 

 give a hard and fast rule as to the length of time a 

 starter can be kept in good condition. It will depend on 

 how well the maker satisfies the conditions necessary for 

 maintaining its purity and strength. The use of im- 

 perfectly sterilized milk, or dirty utensils soon contam- 

 inates it; overripening is likely to injure the flavor. 

 One of the most frequent troubles encountered is the ap- 

 pearance of a slimy or ropy condition in the starter, al- 

 though the acidity developed may be normal and the 

 flavor desirable. It has been found that this condition 

 is not necessarily due to contamination, as was consid- 

 ered true in the past, but rather to some change in the 

 lactic bacteria themselves. If the propagation is con- 

 tinued, the slimy condition will often disappear. 



Starters in "process" butter and oleomargarine. 

 The advance which has recently been made in the science 

 and practice of cream ripening and butter production is 

 utilized most effectively in the treatment of cream in the 



