Leavening
Agents
Gases expand greatly when
they are heated, unlike
gases and liquids. There are
many different types of
leavening agents.
Leavening is the production or incorporation
of gases in a baked product to increase
volume and to produce shape, and texture.

Carbon
Dioxide
Steam
Air
The three main gases that
leaven baked goods. Two of
these gases, steam and air,
are present in all baked
goods.



Formation of air cells is
important during mixing.
Leavening gases are
trapped in these air cells.
Walls are formed of
gluten proteins and egg
proteins, holding gases in
and forming structure.
Exact measurement of
leavening agents are
important because small
changes can produce
major defects in a baked
product.
 Yeast
Fermentation:
It is the process by
which yeast acts on
sugars and changes
them into carbon
dioxide gas and
alcohol. The release of
this gas produces the
leavening action in
yeast products. The
alcohol evaporates
completely during and
immediately after
baking. Yeast is a
microscopic plant that
accomplishes this
fermentation process by
producing enzymes.
Yeast
Yeast is the
leavening agent in
breads, dinner rolls,
Danish pastries and
similar products.
Because Yeast is alive, it is
Sensitive to Temperatures!!!!!!!
 34*F
Inactive (storage temp.)
 60-70*F
Slow Action
 70-90*F
Best Growth (fermentation &
Proofing for bread dough)
 Above 100*F
Reaction Slows
 140*F
Yeast is Killed
 Yeast also contributes to flavor. The longer
the fermentation, the stronger the flavor.
Types of Yeast
Fresh Yeast
Active Dried Yeast
Moist and
perishable
Preferred by
professional
bakers
Dry, Granular Form of
Yeast
Must be rehydrated 4
times its weight in
warm water before
use
Purchased in
1# cakes
lasting 2 weeks
Can be frozen
4 months
25% of yeast cells are
dead due to harsh
drying process
Presence of the
dead cells can have
a negative effect on
dough quality
Avoid using if
discolored or
moldy
Not popular with
baking professionals
Another Type of
Yeast…Instant Dry Yeast!!!
New
product
invented
in 1970”s
The preferred
method of use
is mixing it into
the flour.
A dry, granular form
of yeast, but does
not have to be
dissolved in water
before use.
It contains
very little
dead
yeast, so
less is
needed.
It
produces
more gas
and
quickly.
Sometimes
called rapid
rise or quick
rise yeast.
Chemical Leaveners
Baking
Soda
Baking
Powder
Baking
Ammonia
• If moisture and an acid are present, soda releases carbon dioxide gas,
which leavens product.
• Heat is not necessary for this reaction. Product must be baked at once.
• Are mixtures of baking soda plus one or more acids to react with it.
• They also contain starch to prevent lumping.
• Do not use more than needed because undesirable flavors may be
created.
• Only heat and moisture are necessary for it to work.
• No acids are needed and no residue can affect flavor.
Other Leaveners…..
Beating of fat
& sugar to
incorporate
air.
Some pound
cakes and
cookies are
leavened
entirely by
this process.
Foaming
Creaming
Air
Process of
beating eggs,
with or w/o
sugar, to
incorporate
air.
Foams made
with eggs are
used to leaven
sponge cakes,
angel food
cakes and
meringues.
Steam




When water turns to steam,
it expands 1100 times its
original volume.
Because all baked
products contain some
moisture, steam is an
important leavening agent.
Examples: Cream puffs,
popovers, pie crusts.
If the starting temperature
is high, leavening is at its
greatest.