Of Bicarb and Other Leavening Agents

The husband and I are mightily tired of having builders in the house now.  In fact we hope not to have to have builders in the house for quite a while, though I must make it clear to the Gods of Hubris that is not a wish,  just a statement.  In the last 6 months we have had a new ridge on our thatched roof (that is the straw bit across the top), some penetrating damp fixed (much dust caused with little to show for it except new bare paster patches on our walls), our leaking shower room replaced, broken drains repaired and jet cleaned (the video of the drain leading from the kitchen sink was not a pretty sight – someone before us liked their chip pan!), the oven replaced (well that one is my fault because I turned the old one to a rust bucket by adding steam to the oven when baking bread).

2 weeks ago we thought we were done.  No more clearing everything on the ground floor to upstairs, no more weeks of  ridding the house of fine plaster dust, no more coming home to take dust sheets off the furniture so we had somewhere to sit.  All that was left to do was sort out a  small problem with our kitchen floor.  The old reclaimed oak floorboards in the kitchen laid 7 years ago by the previous owners were lifting slightly and we thought they just needed a quick nip and tuck to sort them out.  Had this been a new house that would have been the case, but the problem with 450 year old houses is that no job is just a quick nip and tuck.

After a few boards had been lifted it turned out that the cause was the old floor underneath which needed stripping out completely including the sticky bitumen used by someone in the 50’s, and after much banging, dust making and sanding,  the old floor putting back.


2 weeks later we are back at the house and the floor looks gorgeous, but the weekend has been dominated by getting our lives back – again!  And yes ye Gods of Hubris and House Maintenance – Enough Already!  We have paid our dues oh Gods for the time being, and we thank you deeply for putting us through these trials as the results are lovely.

So what does any of this have to do with baking I hear you ask?  Well hubby has been going on about the utility room floor and how the grout needs cleaning – especially as everything else is so sparkly.  A quick scan of the internet suggested the best way to do this was  to use a paste of 1 part Bicarbonate of Soda (Baking Soda to my trans-atlantic cousins) and 3 parts household bleach – along with a toothbrush and a lot of elbow grease.  Frankly the clean was nothing short of miraculous as I am sure you will agree.

And what has any o this to do with baking I hear you screaming ?  Well for one, there was no time for baking this weekend, and for two while I was applying an old tooth brush to a tiled floor I realised that Bicarb is something all bakers use in the form of Baking Powder to get the crucial rise to their cakes and apart from a momentary panic about what the bicarb might be doing to our insides if it stripped our floor of years of grime so well, it prompted me to look into why we use Bicarb  in baking and the role of leavening agents in every bakers glorious success.

A Short History of Leavening Agents


Once upon a time there was but one leavening agent that the baker could use – yeast.  Now yeast is a fine natural thing even in its modern variety.  I suspect we found out by chance when a flat bread was left long enough for the natural yeast to get going, and some adventurous early farmer’s wife decided to throw it in the oven rather than throw it away.  The first leavened loaf was the result and I suspect became wildly popular very quickly (well as quickly as knowledge could travel way back when).


The problem with yeast is that it has a very distinct taste.  In bread thats what we are after, but for cake it is a little dominating.  There are some very traditional cakes that still use yeast as the main rising agent, many baked at Easter (and one I desperately want to find the time to try – the Polish Babka), but they use a lot of sweetener and strong flavours.  If you want to keep the flavours clean and the crumb light and even, then yeast is not really right for the job.

Chemical Leavening Agents

It was only in the late 18th Century and the onset of the Industrial Revolution and the beginnings of understanding of basic chemistry that people started experimenting with chemicals.  All of them are based on the fact that when you combine certain alkaline materials with acid ones, they release carbon dioxide.

The very first chemical was Potash. It was easily obtained because it can be sourced from any wood fire ash and made at home. The massive disadvantage of it is that to get a rise you need to use quite a lot of it and it lends (according to some of the historical baking blogs) a very soapy taste to the bake. That can be counteracted by the use of strong flavours and spices, especially ginger, but it is not of much use if you want a delicate flavour. Were I more adventurous I would give it a go but I think from the sound of it I would rather chew on a soap bar – sorry all.


Enter stage left our baking hero – Bicarbonate of Soda!  Bicarb has been used for millennia for many many purposes (just see this web page to see 75 of them). When combined with an acid it has a very vigorous and immediate reaction as you can see from the photo when I added vinegar to bicarbonate.


Its first use in baking was some time in the early 19th century. Records are unclear when,  but this is when quick bread recipes (Irish Soda Bread being the most well known)  emerged which rely on the acid in Buttermilk to get the vigorous chemical reaction. Its huge advantage over Potash is that you need much less to get the quantity of CO2 that will give you a decent rise, which avoids the problem of the soapy taste of Potash. As long as your recipe called for an acid like lemon, vinegar or sour milk then you were fine. But it was not so useful if it did not.

The next innovation was the use of Cream of Tartar (tartaric acid)  which is a by product of wine making coming from the crystals that form on the side of barrels. In its dried form it could then be added direct to the mix along with the bicarbonate without imparting a flavour. The downside of it is that the reaction starts as soon as both ingredients get wet. That means if you don’t get your cake into the oven quickly you will lose a lot of its rising powers.  As you can see I haven’t even opened mine so I haven’t yet come across a recipe for it (and I have no idea why I bought it!)


All of which takes us to a man every baker should bow down and thank – Alfred Bird. Yes my fellow Brits, THE Bird of Birds Custard Powder. But for his wife Elizabeth’s allergy to yeast and eggs, we would not have 2 staples of the baking store cupboard – Baking Powder and Custard Powder.

Alfred was a chemist living in Birmingham who ran an experimental chemists shop in Bull Street.  His experimentation first led to Custard Powder in 1837 (though the dates seem to vary between websites)  – this was mainly dried milk with the eggs replaced with Cornflour and flavourings.  Baking Powder came next in 1843. I can’t find the exact constituents of Mr Bird’s concoction but he was obviously a good businessman as he got an exclusive supply contract to the army during the Crimean War and his son went on to build the brand we know so well though mainly focused in the Custard Powder.

What was his innovation from the basic Bicarbonate and Cream of Tartar? Well he added an additional acid that only reacted with the bicarbonate when heated giving a longer and more durable rise, and cornflour to stabilise the mix whilst stored so it could soak up any atmospheric moisture. The chemicals also led to slower release of of carbon dioxide as you can see form this picture.


Last in our list of heroes comes Dr Oetker – yes he was a real person as well. He was a Pharmacist living in Bielefeld. He tweaked the various recipes that existed at the time, put it into little sachets (those damned Päckchen that drive me mad) and marketed the product to housewives under the brand name “Backin”.

Did he do anything different to Alfred?  Well he was probably a better business man at least. The company is still family owned and run by his great grandson Richard Oetker. Birds went through the more classic British tragedy of being sold to various multi nationals and is now owned by Premier Foods and is a mere gnat in the baking ingredients world  compared to Dr Oetker.


So what else should you know about Baking Powder?

  • The modern ingredients sound delightfully digestible: sodium bicarbonate, mini calcium phosphate and sodium aluminium sulfate.
  • Are there any alternatives ? Well yes if you want to wind back the baking clock 200 years – try potash or yeast.
  • What else ? Oh yes  the main one is that it does go off. That cornflour doesn’t absorb moisture forever. Stick to those use by dates on the packet and if you are unsure, test it by dropping it in water – it should fizz like my picture if it is still ok.

All of which takes us a long way from our builders and my grout. Normal baking will be resumed soon,  especially as I have been asked to make a Macarons Piece Montee for my nieces communion which will need to be made in stages.


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