troy all
the ferment bodies associated with the yeast, as, for example, bread
sometimes becomes soft and stringy, due to fermentation changes after
the bread has been baked and stored. Both bread and flour are subject to
many bacterial diseases, and one of the objects of thorough cleaning of
the wheat and removal of the bran and debris particles during the
process of flour manufacture is to completely eliminate all ferment
bodies mechanically associated with the exterior of the wheat kernel,
which, if retained in the flour, would cause it readily to become
unsound.

178. Production of Soluble Carbohydrates.--Flour contains naturally a
small amount of soluble carbohydrates, which are readily acted upon by
the alcoholic ferments. The yeast plant secretes soluble ferments, which
act upon the starch, forming soluble carbohydrates, and the heat during
baking brings about similar changes. In fact, soluble carbohydrates are
both consumed and produced by ferment action during the bread-making
process. Flour contains, on an average, 65 per cent of starch, and
during bread making about 10 per cent is changed to soluble forms.
Bread, on a dry matter basis, contains approximately 6 per cent of
soluble carbohydrates, including dextrine, dextrose, and sucrose
sugars.[64]

The physical changes which the starch grains undergo are also
noticeable. Wheat starch has the structure shown in illustration No. 33.
The starch grains are circular bodies, concave, with slight markings in
the form of concentric rings. When the proteid matter of bread is
extracted with alcohol and the starch grains are examined, it will, be
seen that some of them are partially ruptured, like those in popped
corn, while others have been slightly acted upon or eaten away by the
organized ferments, the surface of the starch grains being pitted, as
shown in the illustration. The joint action of heat and ferments on the
starch grains changes them physically so they may more readily undergo
digestion. The brown coating or crust formed upon the surface of bread
is mainly dextrine, produced by the action of heat on the starch.
Dextrine is a soluble carbohydrate, having the same general composition
as starch, but differing from it in physical properties and ease of
digestion.

179. Production of Acids in Bread Making.--Wheat bread made with yeast
gives an acid reaction. The acid is produced from the carbohydrates by
ferment action. Flour contains about one tenth of 1 pe