Transcript Facts about Raising Agents

FACTS ABOUT RAISING AGENTS
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Raising agents work by
incorporating a gas into a
mixture.
When you heat the gas it
expands and then it rises.
So the mixture has alight
open texture.
Raising agents maybe
added by mechanical
means such as sieving.
Can be included in the
ingredients such as yeast
and bicarbonate of soda.
Raising agents can be
natural and chemical.
NATURAL RAISING AGENTS.
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The three gases which
make products light are
air,
Steam,
carbon dioxide
In most mixtures you
use more than one
raising agent.
So in a cake it would be
self raising flour but air
would also be trapped
when creaming.
AIR
Air is added
mechanically to food
when you are
 Whisking
 Sieving
 Creaming
 Beating
 Rubbing in
 Rolling and folding
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STEAM
Steam is a raising agent
when a mixture has a
high proportion of liquid
which is then cooked at
a high temperature .
 As the water is then
turned into steam.
Such as
 Yorkshire puddings
 Choux pastry
 Flaky and rough puff
pastry.
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CARBON DIOXIDE
Carbon dioxide is used
as a raising agent
when
 A biological raising
agent like yeast is
used.
 Or a chemical raising
agent like bicarbonate
of soda is used.
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BIOLOGICAL RAISING AGENTS
Yeast is a microorganism.
 When it reproduces it
gives off carbon
dioxide gas.
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THE FOLLOWING CONDITIONS ARE NEEDED
FOR REPRODUCTION.
Warmth between
(25 and 28C) At low
temperatures it slows
down and at high
temperatures it is
killed.
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Liquid
THE FOLLOWING CONDITIONS ARE NEEDED
FOR REPRODUCTION.
Food
 Sugar added to the
mixture or obtained
from flour
Time
 The mixture must be
covered and left to rise
in a warm place.
CHEMICAL RAISING AGENTS
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Chemical raising agents
produce carbon dioxide when
they are heated with a liquid.
Self raising flour is very
convenient as the raising agent
is already added.
Bicarbonate of soda produces
carbon dioxide and washing
soda when heated. The washing
soda is hidden by the flavours
added to the cakes.
Bicarbonate of soda plus acid,
such as soured milk used in
scones. The acid prevents the
washing soda being made.
Baking powder is a convenient
mixture of bicarbonate of soda
and an acid.