Bicarbonate of Soda and Baking Powder Are Both Raising Agents

Back to basic skills which are the backbone for baking we have to remember baking is also a science and if we don't understand whats happening it can all go wrong. A question I often get asked when I am demonstrating is "are bicarbonates of soda and baking powder the same?"

No - its true they are both raising agents, and some times we can use them together, but they are different in the way they react chemically - let’s have a closer look.

Bicarbonate of soda gives a completely different texture and sometimes taste to baking powder. In cooking it gives a nice golden color but can sometimes have a tangy taste. It also produces a very specific texture that baking powder cannot produce.

Here’s the science bit.

Bicarbonate of soda is a pure raising agent. It needs to be mixed with something wet and acidic to start the chemical reaction and make food rise. Bicarbonate of soda is a BASE - think back to the science experiments at school where we mixed bicarbonate of soda, red color, with vinegar and made an eruption of red bubbles, like an erupting volcano. When you mix bicarbonate of soda (BASE) with vinegar (ACID) you get a chemical reaction: this reaction is carbon dioxide (an eruption of bubbles!).

The exact same reaction happens in our baking, cakes, breads, biscuits etc. When a recipe asks for bicarbonate of soda (BASE), it usually includes something acidic like lemon juice, cream of tartar, buttermilk, yogurt, vinegar, molasses, natural cocoa powder (not dutch process), which will create carbon dioxide bubbles helping our baked good to rise.

Bicarbonate of soda is strong, it’s more than double the strength of baking powder but adding more bicarbonate of soda in a recipe doesn’t mean more lift, use just enough to react with the amount of acid in the recipe. Too much bicarbonate of soda and not enough acid means there will be bicarbonate of soda left in the dish - that will leave an unpleasant soapy, metallic, taste in your baking.

What is Baking Powder?

Baking powder contains bicarbonate of soda that has been pre-mixed with the acidic ingredient for you – so all you need to add is the moisture - most baking powder we buy is double acting. This means that the first reaction happens when the baking powder gets wet, and the second reaction occurs when the baking powder is heated. The advantage of baking powder is it has a neutral taste and works really well in recipes that have other neutral-tasting ingredients, like milk.

Chef's Tip:

Self-raising flour is just plain flour that has had baking powder added to it. If you have run out of self-raising flour for a recipe you can make your own. Just add half a teaspoon of baking powder per 100g of plain flour and there you have it, self raising flour!

Once baking powder is mixed with the wet ingredients, the raising agents start fizzing away to create lots of air bubbles.

To make sure you don’t lose this air, get your mixture into the oven as soon as possible or the protein structure that locks air bubbles into the sponge will start to collapse.

It is very important to sift the bicarbonate of soda well as it can get lumpy. Be careful and use exact measurements as the “tangy” taste can spoil a dish with a bitter or soapy note if too much is used.

Remember to check use-by dates as old raising agents lose their effectiveness. I buy new every 12 weeks or so just to be sure.