lso rapidly extending in this country,
Australia and New Zealand.

~Principles of pure-culture cream-ripening.~ In the proper use of pure
cultures for ripening cream, it is necessary first to eliminate as far
as possible the bacteria already present in cream before the culture
starter is added. This result is accomplished by heating the cream to a
temperature sufficiently high to destroy the vegetating organisms. The
addition of a properly selected starter will then give the chosen
organism such an impetus as will generally enable it to gain the
ascendency over any other bacteria and so control the character of the
ripening. The principle employed is quite like that practiced in raising
grain. The farmer prepares his soil by plowing, in this way killing the
weeds. Then he sows his selected grain, which is merely a pure culture,
and by the rapid growth of this, other forms are held in check.

The attempt has been made to use these culture starters in raw sweet
cream, but it can scarcely be expected that the most beneficial results
will be attained in this way. This method has been justified on the
basis of the following experiments. Where cream is pasteurized and no
starter is added, the spore-bearing forms frequently produce undesirable
flavors. These can almost always be controlled if a culture starter is
added, the obnoxious form being repressed by the presence of the added
starter. This condition is interpreted as indicating that the addition
of a starter to cream which already contains developing bacteria will
prevent those originally present in the cream from growing.[163] This
repressive action of one species on another is a well-known
bacteriological fact, but it must be remembered that such an explanation
is only applicable in those cases where the culture organism is better
able to develop than those forms that already exist in the cream.

If the culture organism is added to raw milk or cream which already
contains a flora that is well suited to develop in this medium, it is
quite doubtful whether it would gain the supremacy in the ripening
cream. The above method of adding a culture to raw cream renders
cream-ripening details less burdensome, but at the same time Danish
experience, which is entitled to most credence on this question, is
opposed to this method.

~Reputed advantages of culture starters.~ _1. Flavor and aroma._ Naturally
the flavor produced by pure-culture ferments depends upon the character