r cent of acid;
the dough contains from 0.3 to 0.5 per cent, while the baked bread
contains from 0.14 to 0.3 per cent, but after two or three days slightly
more acid is developed.[64] During the process of bread making, a small
portion of the acid is volatilized, but the larger part enters into
chemical combination with the gliadin, forming an acid proteid. When the
alcoholic fermentation of bread making becomes less active, acid
fermentations begin, and sour dough results. It is not definitely known
what specific organic acids are developed in bread making. Lactic and
butyric acids are known to be formed, and for purposes of calculation,
the total acidity is expressed in terms of lactic acid.

The acidity is determined by weighing 20 grams of flour into a flask,
adding 200 cubic centimeters of distilled water, shaking vigorously, and
leaving the flour in contact with the water for an hour; 50 cubic
centimeters of the filtered solution are then titrated with a tenth
normal solution of potassium hydroxid. Phenolphthalein is used as the
indicator. It cannot be said that all of the alkali is used for
neutralizing the acid, as a portion enters into chemical combination
with the proteids. If the method for determining the acid be varied,
constant results are not secured. Unsound or musty flours usually show a
high per cent of acidity.

[Illustration: FIG. 48.--APPARATUS USED IN STUDY OF LOSSES
IN BREAD MAKING.]

180. Volatile Compounds produced during Bread Making.--In addition to
carbon dioxid and alcohol, there is lost during bread making a small
amount of carbon in other forms, as volatile acids and hydrocarbon
products equivalent to about one tenth of one per cent of carbon dioxid.
The aroma of freshly baked bread is due to these compounds. Both the
odor and flavor of bread are caused in part by the volatile acids and
hydrocarbons. The amount and kind of volatile products formed can be
somewhat regulated through the fermentation process by the use of
special flours and the addition of materials that produce specific
fermentation changes and desirable aromatic compounds. Some of the
ferment bodies left in flour from the imperfect removal of the dirt
adhering to the exterior of the wheat kernels impart characteristic
flavors to the bread. The so-called nutty flavor of some bread is due to
the action of these ferment bodies and, when intensified, it becomes
objectionable. Fungous growths in unsound flour and bread result