ined in a sweet
condition, the maker through this process of pasteurization, and the
use of pure cultures, secures almost perfect control over the type
of fermentation that occurs in the cream, and thus exercises control
over the degree and kind of flavor of the product. This most
scientific type of butter making is now used by the most progressive
butter makers in the leading butter-producing regions of the world.

Pasteurization of the cream also distinctly improves the keeping
quality of butter, a condition doubtless due to the freedom of the
same from organisms other than the lactic bacteria. This is a factor
of as much importance as uniformity, because under modern business
conditions, the surplus production must be kept in storage, and it
is essential that the quality should not deteriorate materially
during this time.

=Process of pasteurization for butter making.= In the pasteurization
of market milk, it is necessary to take into account the effect of
heating on the physical and chemical properties of the milk, and the
degree of heat that can be employed is limited. In pasteurizing
cream for butter, there is no such limitation, and the cream may be
heated to any temperature desired. In Denmark where the process of
pasteurization has been used most extensively, temperatures ranging
from 176 deg. F. to 190 deg. F. are used. The machines are of the
"continuous flow" type, and the cream rather than the whole milk is
treated. To prevent the spread of tuberculosis and other diseases,
the Danish government requires that all cream and milk be heated to
176 deg. F., before the skim milk or butter milk is returned to the
farms.

The heating of the butter fat to high temperatures has an injurious
effect on the texture of the butter, unless the cream is cooled to
50 deg. F., for a period of at least two hours previous to churning.

=Propagation of starters.= As has been previously shown, the quality
of butter depends on the kind of bacteria in the cream or in the
starter added. The commercial starters contain lactic acid bacteria
that have been selected with especial care; most of the starters now
sold contain but a single kind of bacteria; hence, are often called
pure-culture starters. The package purchased contains but a small
quantity, and before the starter can be used in the ripening of
cream, it must be increased in amount. It must also be propagated
from day to day so that a fresh starter shall be available dail