3. As has been pointed out, the ingredients that are actually required
in the making of hot breads are flour, liquid, salt, and leavening, and
to give variety to breads of this kind, numerous other materials,
including sugar, shortening, eggs, fruit, nuts, etc., are often added.
With the exception of leavening agents, none of these ingredients
requires special attention at present; however, the instruction that is
given in _Bread_ regarding flour should be kept in mind, as should also
the fact that all the materials for hot breads should be of the best
quality that can be obtained.
As is known by this time, leavening agents are the materials used to
leaven, or make light, any kind of flour mixture. These agents are of
three classes, namely, _organic, physical_, and _chemical_. The organic
agent is the oldest recognized leavening material, it being the one that
is used in the making of yeast breads; but as a complete discussion of
this class of leavening agents is given in _Bread_ and as it is not
employed in the making of hot breads, no consideration need be given to
it here. Physical leavening is accomplished by the incorporation of air
into a mixture or by the expansion of the water into steam, and chemical
leavening agents are the most modern and accurate of all the agents that
have been devised for the quick rising of flour mixtures.