Temperature of Ripening 203 
cream is, the smaller the amount of starter it is desir- 
able to use. Large amounts of starter should be used 
only in old, unsound or tainted creams. ° 
Temperature of ripening.—The various germs of 
lactie fermentations find their optimum growth point 
at from 80° to°90° F., and milk or cream kept at those 
temperatures will most rapidly become sour. The 
effect of such high temperatures, while favorable to 
the production of lactic acid, is less favorable to 
the texture of the butter, and on this account it is 
desirable to ripen the cream at as low a tempera- 
ture as will insure a fairly rapid growth of the lactic 
germs. A temperature of from. 60° to 70° F. will 
ordinarily bring this about. The amount of acid de- 
veloped in any given length of time will depend not 
only upon the temperature at which the cream has 
been kept, but also upon the number and activity of 
the germs originally present, so that if we have a 
thorough inoculation to start with, a lower temper- 
ature will be sufficient to cause the development of 
the requisite amount of acid; but if only a slight 
inoculation -is present, a higher temperature will be 
necessary. Ordinarily, there will be more germs 
present in the atmosphere during the warm months 
than in the winter, consequently a lower temperature 
will bring about the same degree of acidity in a 
shorter time in summer than in winter. 
The amount of acid necessary.— The amount of 
acid that it is desirable to have in the cream at 
the time of churning depends, of course, largely upon 
the flavors desired by the consumer. It is important 
