Sunday, October 28, 2012

How acidic juices react with baking soda


Bakers understand how acidic juices react with baking soda to make baked goods that rise high and are tender and flaky.


What is a Leavening Agent

Leavening is what makes baking both a delight and a challenge. It is because of leavening agents that your cookies, breads and cakes rise and your pastries are light and flaky. Leavening comes in several varieties mechanical, biological and Chemical.

Mechanical

If you are using the creaming method to mix your dough you are using mechanical leavening. This method incorporates air into the batter or dough and then relies on steam to give the food the lift it needs.

Biological

This is yeast. When you are making bread you use yeast to give your bread dough the rise it needs. How important is yeast? If you have ever seen a matzo then you know what bread without leavening looks like.

Chemical

Chemical leaving is when the baker adds a chemical to the batter or dough to get the same basic effect as adding yeast without adding any flavor to the product.
This chemical can be baking soda or baking powder or some other chemical.


PH – It’s All to Scale

The ph scale goes from 0 (acidic) to 14 (alkaline or base) with 7, the middle of the scale being neutral (like …water).  Lets serve up some science:

In the 1600’s an Irish chemist, Robert Boyle, first started sorting things into two divisions, alkalies and acids. Mr. Boyle sorted them out like this:

*Acids
**Taste sour
**Are corrosive to metal
**Turn litmus red
**Turn less acidic when combined with a base

*While Bases
**Have a slippery feel
**Change litmus blue
**Become less basic when combined with an acid

When a base and an acid are combined they react with each other making each other weaker, this is called neutralization.  This explains how acidic juices react with baking soda.

In 1923 two scientists working independently, Johannes Brønsted and Thomas Lowery, published papers that were very similar. They defined an acid as a substance that can donate a hydrogen ion and defined a base as a substance that can accept a hydrogen ion. Baking soda acts like a base because it can accept a hydrogen ion from an acid.

In the Kitchen Baking Soda is the Ace of Base

Baking soda goes by many different names. Sodium Bicarbonate, Sodium acid carbonate or even NaHCO3. Baking soda will be found in bread recipes (soda bread) cookies, cakes and just about anything that you would need to get a rise from. Baking soda, being a base, will react with any acids that you add to your baking like Sourdough cultures (like a starter dough or sponge), butter milk, yogurt, any unprocessed sugar like molasses, chocolate, unprocessed cocoa, vinegars and acidic fruit juices. 

Another acid that is common in the kitchen is cream of tartar. Technically named potassium hydrogen tartarate it is an acid that is collected from the inside of wine barrels. If you mixed two parts of cream of tartar to one part of baking soda you would have a rudimentary single acting baking powder. This mixture will give you a lot of rise because it is a pre mixed acid and base, which will react when moisture is added. Double acting baking powders will have additional acids added that will react with heat and so will add rise to your product as it cooks while single acting adds all it’s rise before cooking.


How acidic juices react with baking soda

Baking soda is a 9 on the PH scale, a base. While some vinegars and lemon juice are a 2 on the ph scale, they are acids. As we know when an acid and a base are mixed a reaction occurs. When you add your acid, the acidic juice of a lemon to your base the baking soda the resulting chemical reaction crates carbon dioxide, CO2, which adds bubbles to your dough or batter. That is how acid juices react with baking soda. 

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