d by those in the materials added in making the bread.

It is apparent that two breads of the same lot of flour may differ,
according to the method used in making, and also that two loaves of
bread made by exactly the same process but from different lots of flour,
even when of the same grade or brand, do not necessarily have the same
composition, because of possible variation in the flours. In bread made
from flour of low gluten content, the per cent of protein is
correspondingly low.

186. Use of Skim Milk and Lard in Bread Making.--When flours low in
gluten are used, skim milk may be employed advantageously in making the
bread, to increase the protein content. Tests show that such bread
contains about 1 per cent more protein than that made with water.
Ordinarily there is no gain from a nutritive point of view in adding an
excessive amount of lard or other shortening, as it tends to widen the
nutritive ratio.

187. Influence of Warm and Cold Flours on Bread Making.--When flour is
stored in a cold closet or storeroom, it is not in condition to produce
a good quality of bread until it has been warmed to a temperature of
about 70 deg. F. Cold flour checks the fermentation process, and is
occasionally the cause of poor bread. On the other hand, when flour is
too warm (98 deg. F.) the influence upon fermentation is unfavorable.
Heating of flour does not affect the bread-making value, provided the
flour is not heated above 158 deg. F. and is subsequently cooled to a
temperature of 70 deg. F. Wheat flour contains naturally a number of
ferment substances, some of which are destroyed by the action of heat.
The natural ferments, or enzymes, of flour appear to take a part in
bread making, imparting characteristic odors and flavors to the product.

[Illustration: FIG. 50.-BREAD FROM (1) GRAHAM, (2) ENTIRE
WHEAT, AND (3) WHITE FLOUR.

The same amounts of flour were used in making all of the breads.]

188. Variations in the Process of Bread Making.--Since flours differ
so in chemical composition, and the yeast plant acts upon all the
compounds of flour, it naturally follows that bread making is not a
simple but a complex operation, resulting in a number of intricate
chemical reactions, which it is necessary to control and many of which
are only imperfectly understood. Bread of the best physical quality and
commercial value is made of flour from fully matured, hard wheats,
containing a low per cent of acid, no foreign ferment m