CREAM RIPENING 115 



the curd is broken in fine particles. Therefore it should 

 be agitated to about the same consistency day after day. 

 The amounts of starter to taste should be about uniform. 

 A small quantity in the mouth will not taste quite the 

 same as a larger portion. Also the temperature from 

 sample to sample should be approximately the same. 

 A culture that is about 50° F. tastes differently from one 

 with a temperature of about 70° F. Experienced opera- 

 tors unconsciously make allowances for these factors. 

 The flavor should be clean, with a mild acid taste. The 

 first propagation is likely to be somewhat disagreeable 

 because of the presence of some of the original medium 

 in the commercial culture. 



84. How often to propagate. — The lactic acid bacteria 

 are most vigorous when only a small amount of acid is 

 present. Rahn ^ states, " As soon as a determination of 

 fermentation products is possible it shows the fermenta- 

 tion per cell to be faster the younger the culture." Again, 

 he concludes,^ " Old cultures acidify slowly even if trans- 

 ferred into fresh milk; the rate of multiplication is also 

 influenced by long sojourn in the same culture." On 

 account of the starter being much easier to examine when 

 a curd is formed, it is the custom to consider that starter 

 is " ripe " when coagulation has taken place and not when 

 the bacteria are most active, which is before the curd has 

 developed. It should be remembered that the micro- 

 organisms are more active when the curd first forms 

 than when more acid and other products of fermentation 

 have been produced. It is apparent then, from the view- 

 point of the activity of the organisms, that the ideal time 



1 Rahn, Otto, The Fermenting Capacity of the Average 

 Single Cell of Bacterium Lactis Acidi. Mich. Board of Agri., 

 p. 480, 1911. 



