Leavening?

What is Leavening?

Leavening is the process that makes baked goods rise
Baking is essentially gases trapped in a network of proteins and fats that stretch as the gas bubbles expand when heated

​How do we introduce air bubbles ?

• There are three was to introduce air or gases into a batter or dough

  • Physical

  • Biological

  • Chemical
    

Physical Leavening

• Uses physical changes to introduce gases including

  • production of steam

    • requires a hot oven if steam is the only leavening

  • whisking or whipping

  • whisking or beating eggs

    • some recipes call for egg whites to be beaten separately

  • creaming the butter and sugar
    

​Biological

• Relies on a living organism to produce carbon dioxide through fermentation or cellular respiration

• Most commonly uses yeast

• because this relies on a living single celled organism this take time
  

Chemical Leavening

• Relies on a neutralization reaction to produce CO₂

  • Recall that neutralization reactions produce gas, salt and water when acids and bases are added together

• because chemical reactions is faster than living organisms, these products are termed quick breads

Chemical Leavening

​Baking soda

• Sodium bicarbonate (a base) NaHCO₃ breaks down with heat

  • 2NaHCO₃ + heat CO₂ + Na₂CO₃ + H2O

  • This leaves a bitter metallic taste

• Adding an acid will neutralize the sodium carbonate and avoids the bitter tasting compounds

• Acids include buttermilk, vinegar, fruit juice, fruit puree, yogurt, sour cream

Chemical Leavening

​Baking soda

Chemical Leavening

​Baking Powder

• Contains

  • Sodium Bicarbonate (baking soda)

  • dry acids (such as potassium bitartrate)

  • corn starch (absorbs water, keeps it from clumping)

• double acting baking powder contains two acids

• 
  

Chemical Leavening

​Baking Powder

Chemical leavening

• Which leavening agent is used depends on the other ingredients

  • other ingredients are used because of the chemical leavening agent

  • recipes that call for dutch cocoa will used baking powder

  • recipes that use baking soda will use natural cocoa and needs an additional acid
    

Types of dough and batter

Categorized based on the ration of flour to liquid (important for physical leavening)

• pour batter 1:1 ratio, some are easy to pour, some are not- example- the popovers

• Drop batter 2:1 ratio, often used for muffins

• Soft dough 3:1 ratio- yeast breads, require kneading to produce the network

• Stiff dough 6-8:1 withstands handling- pie crust or cut out cookies