What is Leavening Agent?
A leavening agent is any one of a number of substances used in dough and batters that cause a foaming action which lightens and softens the finished product.
When added to dough, they react to produce gases which form the nuclei for the textural development of a biscuit.
Some gases are released by leavening agents CO2, H2O, NH3 and air. Common sources of CO2 are Sodium and Ammonium Bicarbonate.
Define Leavening Agents or Raising Agent
There are 3 leavening agents which is being majorly used in bakery industries. They are:
- Ammonium bicarbonate (ABC)
- Sodium bicarbonate (SBC)
- Sodium acid pyro-phosphate (SAPP)
Sodium bicarbonate is primarily used in baking where it reacts with other components to release carbon dioxide that helps in “rise”.
It is highly hygroscopic and is a widespread leavener used due to its lower cost; lack of toxicity, ease of handling, relatively tasteless end products, and high purity of commercial supplies.
It is active at acidic pH only and stops its activity at basic pH.
Sodium bicarbonate can be substituted for baking powder provided sufficient acid reagent is also added to the recipe.
Many forms of baking powder contain sodium bicarbonate combined with one or more acidic phosphates or cream of tartar.
Above 70 °C, it gradually decomposes into sodium carbonate, water and carbon dioxide. The conversion is fast at 250 °C.
The Reaction is: 2NaHCO 3 → Na 2 CO 3 + H 2 O + CO 2
It is a slow acting acid whose action is elevated by increase in temperature. It reacts with Sodium Bicarbonate in the oven to release sodium carbonate and water.
If CO 2 is released early (where it is not supposed to release) – Inconsistent Product Weight. If CO 2 is released late – surface cracking can occur.
Ammonium bicarbonate is used in the food industry as an agent. They are used as leavening agents where in application low final moisture content is reached in baked products such as short dough and crackers.
The reaction is: NH 4 HCO 3 → NH 3 + H 2 O + CO 2
In this reaction ammonia will be baked out provided the final moisture content is low enough and product is thin and porous enough to allow the gas to escape otherwise ammonia may retain in the product and result in off flavour.
For escaping of ammonia during baking puncturing of biscuit is done. Rotating cutter does this. It is used in products that are to be baked to low moisture content.
Coloring agents- Added to give a better look to the biscuit.
Flavoring agents- It imparts better taste to the biscuits. Flavor makes the end product pleasant and acceptable because a lot of changes take place from mixing of dough to the baking of final product. Added flavour gives rich appetizing taste.
Sweetening agents- They impart sweetness to biscuits. Ex-Sucrose, Invert syrup and Lactose.
A leavening agent must be used in cookies to increase their surface area and bake them to look good in appearance. So 2-3 leavening agents have been used in cookies or biscuits baking.
These leavening agents dissociates at high temperature react with water or heat and release gases in the oven which ultimately results in the puffing of cookies and biscuits.
Cookies or biscuits expands in height and diameter which gives a perfect shape and size to a cookie. The measurement of gauge and diameter is very important factor for packing the cookies in different stock keeping unit (S.K.U.).
Ammonium bicarbonate and sodium bicarbonate used as an ingredients in almost all the recipes of cookies or biscuits but SAPP is a time selective leavening agent which controls the reaction of SBC. SBC starts reacting at high temperature, therefore Ammonium bicarbonate dissociates first and it completely dissociates releasing Ammonia and carbon dioxide.