Incr-Edible Science: Making our own Baking Powder

Whilst my home-made Incr-Edible Science curriculum is primarily one of chemistry, my personal aim is to help L10 become knowledgeable in the ‘why’ of cooking, rather than just the ‘how’.  L10 craves to be in the kitchen every spare moment and would like to run her own business linked in some way to cooking in the future.  The joy of home-schooling is that I am able to tailor their education to that which they are likely to need to know to pursue their future career.  I aim to teach all the children the chemical reactions which occur in their cooking.  With that knowledge will come the ability to play around with recipes, to substitute ingredients and possibly design recipes of their own.  This will be of interest to T11, who loves anything about chemistry, useful to C10 who hopes to run a home of her own one day, and essential to L10 who wants a future in the cuisine industry.  It’s win-win all round!

So far we have learnt in-depth about the science of baking soda.  For all my past Incr-Edible Science posts see here (they include posts about making fizzy lemonade, experimenting with soda bread and much more).  For the past couple of weeks we have been learning how the industry exploited the acid-base reaction of baking soda and produced a more reliable product called baking powder.

First we went over exactly what baking soda does.  I asked what reacted with it and why only certain baked goods use it in their recipe.  They knew the baking soda was alkali which required an acid to produce the carbon dioxide, thus raising the loaf or baked goods.  Therefore only recipes which contained an acid such as vinegar, lemon juice or buttermilk could utilise baking soda as a raising agent.  I asked how cakes rose.  They immediately said baking powder.  I asked them how it might work.  T11 suggested in the same way as yeast.  It was L10 who thought it maybe contained baking soda and a dried milk powder or dried lemon juice.  I liked this path of thinking, and told her she was heading in the right direction.  The children understood that it needed to be dry to maintain its inert properties so that only when mixed with fluid a reaction occurred and not before.  I told them the baking powder did indeed contain baking soda and a dried form of an acid.  They immediately looked on the label which gave its contents: Sodium Bicarbonate and sodium dihydrogen diphosphate.  Needless to say they were none the wiser!

We went shopping in our larder and they saw a packet of tartaric acid.  Given acid was in the name, it was in our baking area of the larder and it was powder they suggested it might work!  I had them read this first.  Then I had them do a bit of investigation, with the goal being to create their own Baking Powder, which would work as effectively as the one bought from the shops.

Firstly they checked to make sure the baking soda or the tartaric acid alone wouldn’t do the job of producing carbon dioxide.  They did this by mixing the same amounts of powder with water.  There was no reaction.

I asked how they wanted to start experimenting.  They suggested a test tube of baking powder, say a teaspoon, and a different test tube with a half teaspoon of baking soda and a half teaspoon of tartaric acid, to which they would add a pipette full of water to each at the same time and then set off a timer for a minute.  I was to take a photo immediately after the water was added and 1 minute later.  The reason for the minute delay was to see if the mixture was still producing carbon dioxide, which it would need to do if it was going to rise a cake:

Immediately as the water was added:both produced a reaction.  The bicarb/tartaric acid mixture was quick, vigorous and over rather quickly
Immediately as the water was added:both produced a reaction. The bicarb/tartaric acid mixture was quick, vigorous and over rather quickly, whilst the baking powder was slow to start
however, one minute later the Baking power solution was still producing carbon dioxide, slowly but steadily.  The homemade mixture had stopped all gas production
however, one minute later the Baking power solution was still producing carbon dioxide, slowly but steadily. The homemade mixture had stopped all gas production

We all had a chat about what we could use to slow down the reaction of the homemade mixture.  T11 remembered talking about how the flour in the soda bread mixture probably helps slow down baking soda reaction, so he suggested we use some flour.  He thought corn flour rather than normal flour to stop us making glue!  So we tried it.  This time we used half a teaspoon of each powder (bicarb, tartaric acid and corn flour) and compared its reaction with  one and half teaspoons of baking powder:

This time the reaction was stronger but slower and much longer lasting for the homemade mixture.
This time the reaction was stronger but slower and much longer lasting for the homemade mixture.
However, after one minute the baking powder was still going strong, whilst the homemade one had ceased gas production all together.
However, after one minute the baking powder was still going strong, whilst the homemade one had ceased gas production all together.

I had them play about with differing proportions.  They were unable to find a mixture that produced exactly the reaction in a test tube as baking powder did.  T11 pointed out though, that a test tube wasn’t exactly the conditions it would be used in, so maybe it would in fact work inside the oven.  They had noticed when they used 2 teaspoons of baking soda to 1 teaspoon of corn flour and 1 teaspoon of tartaric acid, the mixture seemed to continue to bubble.  Not fizz but bubble.  I came and took photos:

Water being added to the two mixtures
Water being added to the two mixtures
A minute later the baking powder mixture is still fizzing away and it looks like the home made mixture isn't doing any thing much
A minute later the baking powder mixture is still fizzing away and it looks like the home-made mixture isn’t doing anything much, until you look down the test tube…
...and see that the mixture is indeed bubbling happily away, producing lots of little carbon dioxide bubbles to rise our baked goods!
…and see that the mixture is indeed bubbling happily away, producing lots of little carbon dioxide bubbles to rise our baked goods!  This carbon dioxide production continued for a long time afterwards

So we gave it a go.  Each lunchtime, whoever is cooking lunch makes some soup and a batch of banana muffins.  The recipe is really simple and requires 6 teaspoons of baking powder.  We substituted our homemade baking powder, baked as normal and this was the rather delicious result:

An almost healthy malt banana muffin with a peanut butter/chocolate topping, risen with our very own homemade baking powder.  Success!!
An almost healthy malt, banana man shaped muffin with a peanut butter/chocolate topping, risen with our very own homemade baking powder. Success!!

Whilst I think T11 would rather be working with ‘real’ chemicals, the girls kept saying to me how much they loved our Incr-Edible Science!  L10 said she would never want to go to school because she would never have this much fun in her science class.  It makes all the hard work worth it when I get comments like that!  They are learning to think, surmise, test theories and eat their chemistry lesson at the end.  Could science be more fun?

29 comments

  1. what a great lesson! I learned so much 🙂 and hope to try it with my girls. I love reading about the thoughts your kids have that take them from one point of an experiment to the next. thanks for sharing!

    1. I’m always fascinated by my children’s thought processes (some make more sense than others!). I particularly wanted to record them in the posts so I could see how their thinking develops over the years.
      I still can’t believe you don’t home school. If you lived nearer I’d happily send my children to you for their education!!

  2. I learned so much from this – thanks Claire! I absolutely love how this curriculum works for all your children’s interests. It is a great foundation for when T(11) takes chemistry further. That muffin looks scrummy!

  3. I like how you’ve recorded your interaction and the children’s ideas. It’s very useful. Like Phyllis, I don’t think I’d ever be able to conduct a science lesson so thoroughly on my own. What you’re doing is absolutely fantastic!

  4. I was going to leave a really smart and educated comment, but I lost my train of thought when I saw that MUFFIN…. My word it looks SooooOO delicious! You are a brilliant teacher Claire! I have never really given much thought to how / why baking powder works. I love how you have taken every-day situations (the kitchen and food) and turned them into Scientific Learning Opportunities! Very useful Science in my opinion! Well done you!

    1. Thanks Liezel! I only came up with the idea because L10 loves to be in the kitchen so much. I thought it might make science and maths more interesting for her. And it really has.
      Thanks for popping by. I’ve missed your smiley comments!!

      1. Thanks for missing me! Each evening once little man is in bed, I think to myself I need to upload a post on my blog…. and then my bed beckons strongly. My husband works on contract in the Middle East, so I am for all practical purposes a ‘single’ Mom and I find that days get away from me… I read every post of yours though! Sometimes on my mobile and then the silly thing gives me grief and I am not always able to comment… but I am here! Learning with your children! x

      2. I so understand about days getting away from you! Only today my son commented that it would be useful for me to have a 30 hour day instead of 24!!
        Good to know you’re doing well!

  5. I pinned this earlier today and then saved it for coming back to later. I was glad I did, I look forward to doing some of this later on.

  6. This is impressive. I would never in a million years thought to have the kids make their own baking powder. What gave you the idea?

    1. Thanks Julie. I’m doing this for my daughter who, ever since she was no age has wanted to do something with baking as her future business. Whilst I was teaching them about bicarb, the natural next step was baking powder and when I researched it I found it was made out of bicarb and a powdered acid. I thought that this was well within my guys ability to produce and possibly even come up with themselves, given what they knew about bicarb, its reactions to acid and rising power. And sure enough L10 got it almost straight away. We’re looking at yeast next.

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