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 
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). 
E i at ee {Or These solutions can be made up very 
Bleed esac o cheaply or bought from the supply- 
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. 
