A Kitchen Chemistry Lesson with a Lemon Honey Cake

This just in: The Online Bakesale for Japan raised $8269 dollars. That will turn into over 80,o00 worth of food at Second Harvest in Japan! Many thanks to my fellow bloggers who donated such beautiful food, and to the generous people who participated in the auction.

Welcome to the April edition of the Burwell General Store recipe swap! This month’s subject was a crazy cake recipe that provided the perfect opportunity to talk about kitchen chemistry- something anyone who bakes may understand intuitively, but that is really helpful to understand more deeply- especially if you’re baking gluten-free.

To recap: Christianna, the fabulous blogger at Burwell General Store found an old cookbook and several months ago invited a group of folks to take one recipe each month and put their own twist on it. I joined the group last month, and it’s been fun to get to know my fellow bloggers, as well as challenge myself in the kitchen. And this month’s cake, was certainly that! Here is the original recipe:

Wacky cake indeed! What excited me about the Wacky cake was that it only used baking soda and vinegar for leavening. No egg, no baking powder- only these two magical ingredients. What is so special about these two ingredients you may ask? Step into my kitchen lab and I will show you!

The Kitchen Divas in Training are now schooling at home, and for science, we are currently studying chemistry. I am as excited as they are about this, because I chickened out of high school chemistry, and in the past year as I have delved more deeply into gluten-free baking, I’ve found myself wishing I understood chemistry better than I do… If you’re curious about chemistry, or have kids who are curious- I highly recommend this series of books- even if they go to traditional school. They’re informative and fun. I personally like all the smiley faces on the different atoms!

So what goes on with vinegar and baking soda when you bake? Well, this:

Cool huh? Baking soda- a base, is reacting with vinegar- an acid. A rather explosive combination.. Add sugar, and the result is amplified. On a molecular level the vinegar and baking soda atoms are switching partners- that’s what’s creating the bubbles.. And, in the kitchen- what happens when you add this to flour and oil, and pop it into a hot oven? Puffy cake!! well…. most of the time, as our kitchen experiments showed.

For this challenge we hypothesized that a cake made with lemon would have a similar lift as the chocolate cake. Chocolate is also considered an acid, and can help increase the amount of bubbles in an acid-base reaction. Honey is also considered an acid- as is an egg…the addition of any of these ingredients can help facilitate the proper reaction to ensure a puffy cake… For our cake, we went with lemon and honey. I had a beautiful jar of the palest yellow acacia honey from our trip to Paris that I had been saving for something special, and since it seemed like sunshine in a bottle, we thought it would be the perfect compliment to the Meyer lemons we picked up.

Now, like all good experimenters, we decided we needed a control. So while one young scientist worked on the experimental recipe, the other created the original Wacky Cake recipe, using the same gluten-free flours as the experimental recipe.

Here’s some of what we learned:

While the acid-base reaction helps give batter a lift, gluten-free chemistry is slightly more delicate. In addition to making sure you have the right proportion of acid to base, you also have to have the right combination of gluten-free flours. Otherwise you end up with gummy cake that tastes like the tapioca balls at the bottom of a bubble tea, like this picture to the left. Notice that the chocolate control cake is puffier. That’s because the chocolate provided additional acid for the reaction.

The shape of the cooking vessel makes a big difference. This recipe calls for mixing the cake in the pan it’s baked in. All well and good, but it’s hard to get the flour wet in the corners. We had the bright idea- well I did at least- of cooking the cake in a stainless steel bowl- the one it was mixed in. I had visions of a rounded lemony puffy cake, not unlike those enormous muffin tins used to make barbie cakes or Easter egg cakes. Not only did we end up cooking cake number two for an hour, but the middle was still uncooked, and upon removing it from the bowl, it looked like this:

The third time was the charm, however. The flours were adjusted properly, we’d gone back to a square baking vessel (more surface to heat the batter), and we’d adjusted the lemon/acid content to where we got a decent lift in the cake!

In conclusion, we learned a lot in our little experiment, including that I rely very heavily on eggs to act as a binder and a lifting agent in some form. To achieve lift using only an acid-base reaction is possible, but easier in a chocolate cake than a citrus cake. Our cake has a great moisture content- due in large part to the honey, and it has a nice crumb. It’s sweet, but not too sweet- and I’ll be having a slice with my morning coffee. No doubt the Kitchen Divas in Training will be asking for a slice with their breakfast as well!

Be sure to stop by the Burwell General Store Recipe Swap Page to get a run down of all the participating bloggers. Links to their sites are there, and you will enjoy the delicious variety of cake offered this month!

Gluten-Free Lemon Honey Wacky Cake

makes 1 9×9 cake

Ingredients

3/4 cup tapioca starch (also called tapioca flour)

3/4 cup brown rice flour  

1/4 cup almond meal

4 tbs sugar

2 tsp baking soda

1/2 tsp xanthan gum

zest from 2 lemons

5 tbs melted butter

1 cup cold water

1/2 cup honey

3 tbs lemon juice

Directions

In the pan you are baking in, place all the dry ingredients and stir with a fork to fully mix. Using a 2 cup measuring cup, combine water, honey and lemon juice. Stir until honey has dissolved. Next, make a hole in the center and add the melted butter. While stirring, add the remaining liquid. You will see bubbles start to form as the baking soda and lemon juice begin to react. Combine ingredients and place in a 400 degree oven for 5 minutes. Turn to 350 and cook an additional 20 minutes. Cake is done when a toothpick comes out clean.

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