206 



BUTTER-MAKING. 



upon the taste and smell, and the appearance of the cream, 

 to decide when the cream has been ripened to the desired 

 degree of acidity. Makers with a great deal of experience are 

 able to tell quite accurately by the appearance of the cream 

 and its taste and smell when it has been properly ripened. 

 Well-ripened cream gets an apparently granular and glistening 

 condition. It has a pleasant, mild acid taste, and a good 

 clean sourish aroma. 



As the flavor of properly ripened cream will vary somewhat 

 according to the different degrees of richness of the cream, it 

 is very easy to be deceived by the 

 senses. For this reason it is advisable 

 to use a special test with which to 

 measure the amount of acid developed 

 in the cream. There are two acid tests 

 in general use now in creameries, viz., 

 " Mann's Test" and the "Farrington 

 Test.". 



Mann's Test. Mann's test consists 

 of measuring the acid in the cream 

 i by means of an alkali of a definite 

 known strength. The kind of alkali 

 used is usually a .1 normal solution of 

 caustic potash (KOH) or soda (Na.OH). 



FIG. 129. Apparatus for rrn solutions ran be made im vprv 

 Mann's acid test. In- J 



stead of the burette the cheaply or bought from the supply- 

 alkali can be kept in a , ... . . , , 

 large bottle, as shown in houses. Mann s test is based upon mea- 



Fig. 131 and 130. suring out 50 c.c. of cream by means 



of a pipette. A few drops of an indicator (phenolphthalein) 

 is added. This indicator gives a red color in an alkaline solu- 

 tion, and no color in an acid solution. The .1 normal alkali 

 is poured into a burette, and the solution allowed to run into 

 the 50 c.c. of cream and stirred thoroughly until it begins to 

 turn pink in color. At this point it is neutral. The number 

 of cubic centimeters of alkali required to neutralize the acid 

 in 50 c.c. of cream indicates the number of degrees of -acid. 



