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 

 lactic 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 



