260 N. H. AGR. EXPERIMENT STATION. [Bulletin 141 



developed in the cream by ripening at a temperature between 

 60° and 70° F. this range of temperature is to be recommended. 

 At this temperature the lactic acid bacteria or those which tend 

 to develop good flavors and aroma in the butter multiply com- 

 paratively faster than other bacteria, enabling the farmer to 

 check and overcome the growth of the latter. It is, therefore, 

 possible to get desirable flavors developed in cream which per- 

 chance had a small majority of undesirable bacteria, by keeping 

 the temperature within this range and as near as possible 65° F. 

 while the same cream left to ripen at a higher temperature would 

 produce undesirable flavors. When the temperature is lower 

 than 60° the lactic acid producing bacteria grow and multiply 

 very slowly and it is therefore difficult to get the cream suf- 

 ficiently sour for churning. Furthermore, a class of bacteria 

 which produces bitter flavors grow quite well at a temperature 

 between 50° and 60° F. and as a result cream which has been 

 kept for several days at this temperaure often has a decidedly 

 bitter taste. 



While the ripening of the cream takes .place it should be stirred 

 frequently to keep the bacteria evenly distributed, to keep the 

 cream uniform in temperature and to keep the fat evenly dis- 

 tributed. These factors tend to give a uniform souring of the 

 cream. 



Degree of Ripeness.^Remembering that the ripening of 

 cream is done principally to produce flavor, the question arises, 

 how much flavor is it desirable to produce, or, in other words, 

 how sour is it desirable to have the cream? A great deal of 

 farm butter has too much flavor, due to not having the right 

 kind of bacteria in control from the beginning. 



The degree to which the cream is ripened on New Hampshire 

 farms varied considerably; 4.2% churned sweet cream, 91.7% 

 had the cream moderately sour and 4.1% had the cream very 

 sour before churning. When sour cream butter is made the 

 cream is ready to churn when it has a mild but distinctly sour 

 taste, not too sharp or bitter, and has a glossy, brittle appearance. 

 There are two common methods in use for ascertaining when the 

 cream is ready for churning, first by using the acid test and 

 second by taste and aroma. The acid test consists of measuring 

 by means of an alkali solution of known strength the amount of 



