Butter Making 
13 
ripening. The amount of acid which should be developed in a starter 
is from 0.6 to 0.7 per cent, for at this time it contains the largest 
number of active bacteria. Another way of judging is by the 
thickening of the milk which usually takes place at about 0.7 per cent, 
acid when the temperature is 65 degrees to 70 degrees F. 
Ripening the Cream. 
For every ten gallons of cream, use from one to two gallons 
of starter, or, in other words, from ten to twenty per cent. The 
exact amount can not be stated definitely, as much depends upon the 
age, acidity, temperature and thickness of the cream, of which the 
dairyman must be the judge. The cream should be sweet and as 
fresh as possible when the starter is added, and as much starter 
should be used as can be handled conveniently. In warm weather 
either ice or pasteurization must be resorted to to keep the cream 
sweet from one churning to the next, or else the churnings must be 
more frequent. Too much must not be expected of a starter, for 
while it may improve the quality of butter made from old, stale 
cream that has soured, it gives the best results when used with fresh 
sweet cream. A temperature of 70 degrees F. should be maintained 
during the ripening which is completed when the cream has acquired 
an acidity of 0.5 to 0.6 per cent. Under favorable conditions, this 
will require from six to eight hours. During this time, the cream 
should be stirred frequently to insure uniform ripening. 
In regard to ripening, Rasmussen (1) says, “It should be consid¬ 
ered that too sour cream, as a rule, gives a butter with a strong flavor 
and with poor keeping qualties and, therefore, the danger of getting 
the cream too sour before churning is greater than not getting 
it sour enough.” In the absence of any chemical means for deter¬ 
mining the per cent, of acid present, the only alternative is experience 
in judging the ripeness by the taste, aroma and appearance. As a 
general thing, ‘‘cream is ready to churn when it has a mild but dis¬ 
tinctly sour taste, not too sharp or bitter, and has a glossy brittle 
appearance.” 
Pasteurized Cream. 
During recent years, the pasteurization of cream for butter mak¬ 
ing seems to be gaining favor in our best creameries. In fact this 
practice has become almost a necessity in those localities where cream 
of all kinds is gathered from various sources. The butter maker has 
come to realize that if he is to have control over his finished product, 
so that he shall have some assurance of the constant and uniform 
quality of the output, he must resort to means by which he can elimin¬ 
ate the variable factors in his cream, namely, those undesirable bac¬ 
teria and disagreeable flavors which will develop later on and make 
their presence manifest in the finished article. By heating the cream 
( 1 ) Bui. 141 , New Hampshire Exp. Sta., 1909 . 
