Cooking with chemistry: upraising

I’ve always wondered which raising agents makes the best chocolate chip cookies. So here’s me, with some flour, sugar, eggs, butter and lots of different raising agents. I adapted this recipe for classic chocolate chip cookies, doubling the amounts given in the recipe and then splitting the overall amount into six different batches.

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Sodium hydrogen carbonate (baking soda, bicarbonate of soda) was recommended by the recipe. This common leavening agents in modern recipes produces CO2 above 80°C and in the presence of acidic compounds in the dough.

Produces flat thin cookies, which means they become quite crunchy. Since I love crunchy, these were my second favourite ones.

Baking powder

Another very common raising agent is this mixture of NaHCO3 and E450, diphosphate or pyrophosphate (P2O74–). The phosphate salts are slightly acidic, which aids the release of carbon dixoide.

The baking powder cookies didn’t become quite as flat, they had a very slightly chewy centre.


Although the package said ‘cream of tartar’, which should be KC4H5O6, ie potassium hydrogen tartrate or potassium bitartrate, the ingredients list said just ‘potassium tartrate’, which is K2C4H4O6. It is not really a raising agent, but an acidic component that helps activate NaHCO3 or is uses to stabilise whipped egg whites or whipped cream.

No wonder the biscuits containing only K2C4H4O6 did not really rise at all, they were dense and chewy. Not my favourites at all.

Phosphate-free baking powder

This type of baking powder contains mostly Na2CO3 (sodium carbonate) and some K2C4H4O6 as the acidic component that helps the carbonate release CO2.

The result ended up being quite similar to regular baking powder. I’ve read that this type of baking powder has less of its own taste than the phosphate-containing variety, but I don’t think I have the palate to notice these subtle differences (I’m usually just happy to stuff them into my face).


Potassium carbonate or potash is one of the classic leavening agents that people used before there was baking powder. Nowadays it’s mainly used in recipes such as gingerbread, sometimes in combination with NH4HCO3.

These biscuits didn’t rise very much and ended up being quite chewy. Some people prefered this, but I didn’t like them very much.


Ammonium hydrogen carbonate or ammonium bicarbonate. The raising agent, also called or salt of hartshorn, hornsalt or baker’s ammonia, also contains ammonium carbonate ((NH4)2CO3) and small amounts of ammonium carbamate (NH4CO2NH2).

The name ‘hornsalt’ comes from the fact that people used to make ammonium bicarb by dry distilling grated animal bone, hair, horn and leather (ewww…). It is another traditional leavening agent for things like Swedish Drömmar, Danish cruller or German Lebkuchen.

When heated, it not only produces  CO2 but also NH3, ammonia. This is why hornsalt is only used biscuits and other flat bakes. If you’d try to make bulky bakes like a cake with ammonium bicarb, the gaseous ammonia wouldn’t be able to escape during baking and the cake would get a nasty ammonia taste.

The cookies made with hornsalt were actually my favourite. They were extra flat and extra crunchy.

So now I had more than 60 cookies and a very realistic chance of developing diabetes if I kept them. Good thing there’s my work colleagues, always happy to make short work of any baked goods.2016-11-02 11.06.26.jpg


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