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PRACTICAL PAPERS—BREAD-MAKING-. 817 
and the action of fermentation, it will be necessary to notice 
the properties of some of the constituents of flour as given 
above. The flour of all the cereal grains, contains certain ni¬ 
trogenous ingredients, known as albuminoids on account of 
their near resemblance to animal albumen. These substances 
are classed together above, under the general term gluten. 
This nitrogenous portion of the flour, is the flesh-forming por¬ 
tion, while the sugar, starch and gum, are essentially fat-form¬ 
ing in their natures. The gluten of wheat flour, which con¬ 
sists largely of vegetable fibrin, contains also a minute quan¬ 
tity of a very soluble albuminoid, known as gliadin, or veget¬ 
able glue, resembling in many respects, animal glue. This 
gliadin being very tenacious in its nature, holds together the 
particles of vegetable fibrin, giving to the dough a peculiar 
adhesive quality. Now when fermentation begins, the car¬ 
bonic acid gas liberated, is prevented from escaping by the 
tenacity imparted to the dough by the gliadin, while the ex¬ 
pansive force of the gas is sufficient to cause the raising of 
the dough, the gas occupying the open pores found within the 
loaf. 
It is in wheat only that gliadin is found in sufficient quan¬ 
tity. And it is its absence in rye, oats and barley, that causes 
the bread made from the flour of these grains, to be dense and 
heavy, as from want of tenacity in the dough the gases escape, 
instead of raising the mass into a light, porous, spongy loaf. 
Various means have been devised to ensure the liberation of 
the carbonic acid gas necessary to give lightness to the dough. 
That earliest in use was “ leaven,” and we read in the early 
bistory of the Jews, of leavened and unleavened bread. 
It is well known that many of the substances rich in nito- 
gen are most liable to putrefaction or decay, and not only un¬ 
dergo this change themselves, but induce decomposition in 
other compounds when brought into contact with them. To 
this class of easily fermentable substances belong the nitro¬ 
genous compounds found in the flour of the cereal grains. 
The leaven, or ferment, so commonly used in bread making, 
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