198 BUTTER-MAKING. 
and thus prevents the fat which is at the surface from coming 
in direct contact with the flavoring substances formed at the 
bottom. If the surface layer of fat and casein were exposed 
to favorable conditions, the point might be made that the sur- 
face exposure is more desirable than if the fat were in a state 
of perfect emulsion with the rest of the constituents of cream. 
But such is not the case. The layer of fat and curdled casein, 
when allowed to form at the surface, is likely to be contami- 
nated with putrefactive organisms. Especially is this so if 
the cream is allowed to stand in such a condition very long 
in a warm ill-ventilated room. If the constituents of cream 
are kept well mixed by stirring, the lactic acid checks the 
development of putrefactive germs, which may accumulate at 
the surface; the cream is ripened more evenly, and the flavor- 
ing substances have the best facilities of coming in contact 
with and being absorbed by the fat. 
The authors have noticed that high-scoring contest butter 
is usually made from cream which has been stirred judiciously 
at intervals. The most notable prize winners have stayed up 
with their cream all night, or part of the night, to watch the 
ripening process, and to stir the cream occasionally. It would 
not be practical to advise this method, but cream should re- 
ceive a judicious amount of stirring at intervals during the day, 
and if it is allowed to stand over night, it should be stirred 
the last thing in the evening before retiring. 
NaTuRAL AND ARTIFICIAL RIPENING. 
Cream-ripening as a whole, as practiced to-day, may be 
divided into two groups: viz., (1) Natural, and (2) Artificial. 
Natural.—Natural cream-ripening consists in letting the 
raw cream stand at a certain temperature until it is sour, then 
cooling it to the churning temperature. This method used to 
be practiced nearly altogether, but now experimental and 
practical evidence prove that this is not the method by which 
the best butter can be produced. Natural ripening may, or 
