is made by the churning or agitation of
cream and is composed mainly of milk fats and water, together with
smaller amounts of ash, salt, casein, milk sugar, and lactic acid.
Average butter has the following composition:

============================
|Per Cent
Water | 10.5
Ash and salt | 2.5
Casein and albumin | 1.0
Fat | 86.0
============================

When butter contains an abnormal amount of water, it is considered
adulterated. According to act of Congress standard butter should not
contain over 16 per cent of water nor less than 82.5 per cent of fat.

119. Digestibility of Butter.--Digestion experiments show that
practically all of the fat, 98 per cent, is digestible and available for
use by the body. Butter is valuable only for the production of heat and
energy. Alone, it is incapable of sustaining life, because it contains
no proteid material. It is usually one of the more expensive items of
food, but it is generally considered quite necessary in a ration.[5] It
has been suggested that it takes an important part mechanically in the
digestion of food.

120. Adulteration of Butter.--In addition to containing an excess of
water, butter is adulterated in other ways. Old, stale butter is
occasionally melted, washed, salted, and reworked. This product is known
as renovated butter, and has poor keeping qualities. Frequently
preservatives are added to such butter to delay fermentation changes.
Oleomargarine and butterine are made by mixing vegetable and animal
fats.[40] Highly colored stearin, cotton-seed oil, and lard are the
usual materials from which oleomargarine is made. It has practically the
same composition, digestibility, and food value as butter. When sold
under its true name and not as butter, there is no objection, as it is a
valuable food and supplies heat and energy at less cost than butter. The
main objection to oleomargarine and butterine is that they are sold as
butter.[41]

The coloring of butter is not generally looked upon as adulteration, for
butter naturally has a more or less yellow tinge. According to an act of
Congress, butter colors of a non-injurious character are allowed to be
used.

CHEESE

121. General Composition.--Cheese, is made by the addition of rennet
to ripened milk, resulting in coagulation of the casein, which
mechanically combines with the fat. It differs from butter in
composition by containing,