Leavening Agents

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Leavening Agents
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Objectives

• Explain the purpose of leavening agents in baked
  goods.
• Identify natural leavening agents and describe
  how they work.
• Explain the chemical process by which baking soda
  and baking powder leaven baked goods.
• Describe the role of yeast in leavening.

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Purpose of Leavening

• To create light, fluffy baked goods.
• Leavening means to lighten.
• Heat is added to batter or dough
• Bubbles of gas cause the mixture to inflate.
• The main gases that leaven are
• Air
• Steam
• Carbon dioxide

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Natural Leavening Agents

• Air
• Steam

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Air as a Leavening Agent

• Sift flour
• Beat fat with sugar
• Whip batter, cream or egg whites
• Fold the flour into the foam

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Using Steam to Leaven

• Water in liquid produces steam.
• Requires a very hot oven.
• Steam forms and
• batter expands
• around it.

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Chemical Leaveners
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Baking Soda and Baking Powder

• A chemical reaction occurs that produces carbon
  dioxide.

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Baking Soda

• Sodium bicarbonate
• Made from NaOH and H2CO3
• When heat is added a chemical reaction between
  the liquid and the NaHCO3 occurs and gas is a
  product.

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Baking Soda

• If an acid is not added to the recipe sodium
  carbonate will form. (NaCO3)
• This is a bitter tasting solid that gives an off
  color flavor to the baked good.

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2NaHCO3 CO2 Na2CO3 H2O
Baking Soda
Gas
Bad Taste Yellow Color
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Preventing Na2CO3

• Add an acid to the recipe
• Buttermilk
• Vinegar
• Honey
• Fruit juice
• Cream of Tartar

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Baking Powder

• Is a leavening compound that contains
• Baking Soda
• Dry Acid
• Filler (Cornstarch)

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Two Types of Baking Powder

• Single Acting
• CO2 released when liquid is added.
• Acid is soluble in cold liquid.
• Homemade baking powder.
• Rarely sold commercially in US

• Double Acting
• Contains two acids.
• One reacts with cold liquid.
• One reacts with heat
• Most CO2 released when heat is added.

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Strength of Baking Powder

• By Federal Law
• Must yield 12 g CO2/100 g powder
• BP used in home 14
• BP used in industry 25

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Use the Correct Amount of BP

• Too Much
• Product rises too far and collapses
• 2. Too Little
• Compact product
• with little volume

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Storing Baking Powder

• Air Tight Container
• Reacts in the container
• Products wont produce as much CO2

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Ammonium Bicarbonate

• Used in Industry
• Creates CO2
• Bakers Ammonia
• Used in crackers and thin cookies
• Produces Ammonia gas that has bad smell and odor.
• Thin products this gas dissipates.

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How It All Works

• Eggs and gluten provide the structure for the
  steam, air or CO2 to form around.
• The structure sets when the protein in the eggs
  and gluten coagulate.
• Large pockets sometimes seen in baked products
  are created by the steam, air and CO2.

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Organisms that Leaven

• Yeast is a living organism.
• It leavens baked goods by producing carbon
  dioxide gas through fermentation. As it consumes
  sugars
• the Yeast produces
• ethyl alcohol and
• carbon dioxide gas.

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Producing CO2 with Yeast

• Yeast is a microscopic organism.

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Fermentation

• Process in which yeast splits complex organic
  compounds into simpler substances.
• CO2 is a product.
• Yeast converts sugar into alcohol and carbon
  dioxide.

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Carbon Dioxide
Yeast
C6H12O6 2C2H5OH 2CO2
Ethyl Alcohol
Glucose (sugar)
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Fermentation Continued

• Ethyl Alcohol Evaporates during baking.
• Carbon dioxide causes the product to rise.
• Yeast is killed by high baking temperatures and
  fermentation is stopped.

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Assignment

• Use the internet and research The History of
  Yeast. Write a one page paper that describes
  how yeast was used in cooking in the past and
  compare it to the way we use yeast today.

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Making Leavened Products
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Leavened Products

• Yeast Breads
• Quick Breads

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Quick Breads

• Made with baking powder or baking soda.
• Doesnt need to rise as long as yeast bread.
• Examples
• MUFFINS
• COFFEE CAKE
• BISCUITS

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Four Categories of Quick Breads

• Pour Batters
• Drop Batters
• Soft Doughs
• Stiff Doughs

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Batters and Doughs

• Batters
• contain more
• liquid than
• doughs.

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Types of Batters

• Pour batters
• Drop Batters

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Pour Batters

• Equal ratio of flour to liquid
• Steam is the main leavener
• Examples
• Popovers
• Cream puffs
• Waffles
• Pancakes
• Cake

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Drop Batters

• Two parts flour One part liquid
• Mix only until dry ingredients are moist
• Examples
• Muffins
• Cookies

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Doughs

• Soft Doughs
• Stiff Doughs

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Soft Doughs

• 3 parts flour 1 part liquid
• More mixing to develop gluten may need to be
  kneaded
• Example
• Baking Powder Biscuits

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Stiff Doughs

• 6 to 8 parts flour 1 part liquid
• Drier than soft doughs
• Examples
• Pie crust
• Pasta

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Leavening in Cakes

• Shortened Cakes
• Unshortened Cakes

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Shortened Cakes

• Contain
• Margarine, Shortening, Butter (fat)
• Chemical Leavener (Baking Powder/Soda)
• Air as minor leavener

• Examples
• White cake
• Yellow cake
• Chocolate cake

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Unshortened Cakes

• Pound Cake
• Leavened with air and steam
• Pound cakes
• Sponge
• Leavened by air beaten into egg foam
• Steam a minor leavener
• Angel Food and other
• sponge cakes

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Assignment

• Lab preparation
• You will be making pancakes in lab. Use the
  recipe as a guide and list all supplies
  equipment you will use. Write a summary of the
  steps you will follow.