in the
liberation of volatile products, which impart a musty odor. Good odor
and flavor are very desirable in both flour and bread.

181. Behavior of Wheat Proteids in Bread Making.--Gluten is an
ingredient of the flour on which its bread-making properties largely
depend. The important thing, however, is not entirely the quantity of
gluten, but more particularly its character. Two flours containing the
same amounts of carbohydrates and proteid compounds, when converted into
bread by exactly the same process, may produce bread of entirely
different physical characteristics because of differences in the nature
of the gluten of the two samples. Gluten is composed of two bodies
called gliadin and glutenin. The gliadin, a sort of plant gelatin, is
the material which binds the flour particles together to form the dough,
thus giving it tenacity and adhesiveness; and the glutenin is the
material to which the gliadin adheres. If there is an excess of gliadin,
the dough is soft and sticky, while if there is a deficiency, it lacks
expansive power. Many flours containing a large amount of gluten and
total proteid material and possessing a high nutritive value, do not
yield bread of the best quality, because of an imperfect blending of the
gliadin and glutenin. This question is of much importance in the milling
of wheats, especially in the blending of the different types of wheat.
An abnormally large amount of gluten does not yield a correspondingly
large loaf.

[Illustration: FIG. 49.--BREAD FROM NORMAL FLOUR (1);
GLIADIN EXTRACTED FLOUR (2); AND FROM FLOUR AFTER EXTRACTION OF SUGAR
AND SOLUBLE PROTEIDS (3).]

Experiments were made at the Minnesota Experiment Station to determine
the relation between the nature of the gluten and the character of the
bread. This was done by comparing bread from normal flour with that
from other flour of the same lot, but having part or all of its gliadin
extracted.[64] Dough made from the latter was not sticky, but felt like
putty, and broke in the same way. The yeast caused the mass to expand a
little when first placed in the oven; then the loaf broke apart at the
top and decreased in size. When baked it was less than half the size of
that from the same weight of normal flour, and decidedly inferior in
other respects. The removal of part of the gliadin produced nearly the
same effect as the extraction of the whole of it, and even when an equal
quantity of normal flour was mixed with that from w