A leavening agent is a substance that forms bubbles of gas in a batter or
dough, thus leavening it or making it porous. During the baking the ex-
pansion of the gas produced stretches the batter ; then the heat coagulation
of the protein of the flour or of the flour and eggs sets the dough structure.
Yeast produces carbon dioxide gas in doughs, but with yeast a period of
time is necessary for enough gas to be produced to leaven the dough suf-
ficiently before the product can be baked.
Steam. One of the simplest ways of leavening is by steam. One volume
of water forms more than 1600 volumes of water vapor, so that steam
may have considerable leavening ability. Steam is most effective as a leaven-
ing agent in thin batters in which the proportion of water is large, such as
popovers and cream puffs. Medium batters, of which griddle cakes and
muffins are examples, are partially leavened by steam and partially by the
gas produced from the added baking powder. Steam does not aid to such
a great extent in leavening the batters and doughs containing little water
both because of the small proportion of water used and because of the large
amount held by the starch and protein.
Soda. Sodium bicarbonate or soda may be used for a leavening agent.
When heated it gives off gas as follows :
2 NaHCOs + Heat > Na2C03 + H2O + CO2
sodium sodium water carbon
bicarbonate carbonate dioxide
The residue, sodium carbonate, gives a disagreeable taste and produces a
yellow color in the baked product. For this reason some substance is used
with soda that combines with it to give an end product that does not affect
the flavor or color of the food so decidedly as does sodium carbonate.
Hydrochloric acid. The following reaction is typical of baking
powder reactions in that an acid substance is combined with the soda to
produce the gas. According to Hart, the first patent for a baking powder,
taken by Dr. Whiting in 1837 in England, was for the formula given
below. In the baking powders of today an acid salt, in powder form,
replaces the acid of this formula.
HCl -f NaHCOa > H2O + CO2 + NaCl
hydrochloric sodium water carbon sodium
acid bicarbonate dioxide chloride
447
448 BATTERS AND DOUGHS
Baking ammonia. Baking ammonia has been used for years in baked
products and is still used in many bakeries for some goods. Baking am-
monia is ammonium bicarbonate; when heated it breaks up to form am-
monia, water, and carbon dioxide. Since two gases are produced it is a
very efficient leavening agent. The chief objection to its use is that, unless
NH4HCO3 + heat > NH3 + H2O + CO2
ammonium ammonia water carbon
bicarbonate dioxide
all the ammonium bicarbonate is broken up and all the ammonia gas
driven off, the taste and smell of ammonia remain in the baked product.
For this reason it is used in baked products like cookies and cream puffs,
that are small and thin or have thin walls.
Page 365
Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
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A leavening agent is a substance that forms bubbles of gas in a batter or
dough, thus leavening it or making it porous. During the baking the ex-
pansion of the gas produced stretches the batter ; then the heat coagulation
of the protein of the flour or of the flour and eggs sets the dough structure.
Yeast produces carbon dioxide gas in doughs, but with yeast a period of
time is necessary for enough gas to be produced to leaven the dough suf-
ficiently before the product can be baked.
Steam. One of the simplest ways of leavening is by steam. One volume
of water forms more than 1600 volumes of water vapor, so that steam
may have considerable leavening ability. Steam is most effective as a leaven-
ing agent in thin batters in which the proportion of water is large, such as
popovers and cream puffs. Medium batters, of which griddle cakes and
muffins are examples, are partially leavened by steam and partially by the
gas produced from the added baking powder. Steam does not aid to such
a great extent in leavening the batters and doughs containing little water
both because of the small proportion of water used and because of the large
amount held by the starch and protein.
Soda. Sodium bicarbonate or soda may be used for a leavening agent.
When heated it gives off gas as follows :
2 NaHCOs + Heat > Na2C03 + H2O + CO2
sodium sodium water carbon
bicarbonate carbonate dioxide
The residue, sodium carbonate, gives a disagreeable taste and produces a
yellow color in the baked product. For this reason some substance is used
with soda that combines with it to give an end product that does not affect
the flavor or color of the food so decidedly as does sodium carbonate.
Hydrochloric acid. The following reaction is typical of baking
powder reactions in that an acid substance is combined with the soda to
produce the gas. According to Hart, the first patent for a baking powder,
taken by Dr. Whiting in 1837 in England, was for the formula given
below. In the baking powders of today an acid salt, in powder form,
replaces the acid of this formula.
HCl -f NaHCOa > H2O + CO2 + NaCl
hydrochloric sodium water carbon sodium
acid bicarbonate dioxide chloride
447
448 BATTERS AND DOUGHS
Baking ammonia. Baking ammonia has been used for years in baked
products and is still used in many bakeries for some goods. Baking am-
monia is ammonium bicarbonate; when heated it breaks up to form am-
monia, water, and carbon dioxide. Since two gases are produced it is a
very efficient leavening agent. The chief objection to its use is that, unless
NH4HCO3 + heat > NH3 + H2O + CO2
ammonium ammonia water carbon
bicarbonate dioxide
all the ammonium bicarbonate is broken up and all the ammonia gas
driven off, the taste and smell of ammonia remain in the baked product.
For this reason it is used in baked products like cookies and cream puffs,
that are small and thin or have thin walls.