Spring. It’s almost here.
The chills that settled within me as I put down my chunky winter coat and slipped into a light spring jacket made me feel energetic and happy. I would walk out from my home or from a building and would be blissfully surrounded by that nostalgic spring air; the one that I fail to describe but probably smells like budding flowers and all the happy little creatures in our soil. It reminded me of the stomach fluttering feeling that I get every single year, allowing my mind to trickle back to my high school career. As I reminisced, I recalled the term project I completed for nutrition class. It involved the preparation of a three-course meal; undeniably the best project assigned to me! It was the first (and surprisingly last) time that I prepared homemade cookies, so with this burst of energy I decided to try that again!
I flipped through my sister’s cook book and managed to find the recipe I used all those years ago. Since I was already going to create a mess in the kitchen it made the most sense to double my dessert action, so I decided to bake a cake as well! As I sorted through my pantry – assembling my team of ingredients – I realized that the cookies required baking soda while the cake called for baking powder. We grow up knowing they’re different but I for one did not know the difference, so I decided to find out.
The two are quite similar as they both contain what is called sodium carbonate, a basic component. Baking powder however has an added acid component. When incorporated with the wet ingredients, the acidic and basic components of baking powder will react to produce carbon dioxide (CO2). The high concentration of CO2 in the batter – alongside the relatively low concentration of CO2 in the surrounding air – create a gradient. This gradient then increases the tendency of the gas to diffuse out into the air, creating gaps within the pastry mixture. Imagine you have the opportunity to travel anywhere in the world. Most likely you’d want to visit a place that is quite different from your home, no? You’d want a thrilling experience, one for the books! That’s similar to these CO2 molecules as they’d rather travel to a place they haven’t “experienced yet”, a place that has less of them (in the open air). The pockets they once occupied then create that fluffy cake that you just can’t stay away from!
While both chemical leavening agents, baking soda played a completely different role in my cookies. They promoted what are called, Maillard reactions; the browning of food that results in rich and intense flavours. Recall browning onions and the warm aromas that diffuse into your kitchen as caramelization progresses. The reaction occurs between amino acids (the building blocks of protein) and sugars. In basic solutions, sugars will react with amino acids to form melanin, providing cookies with that toasted toffee color. Of course, in order to first produce this basic environment, we must introduce a substance of that nature – hence the need for baking soda!
Now, you’re probably thinking that an acidic component could easily be added to baking soda, such as cream of tartar or vinegar in buttermilk pancakes. Pat yourself on that back because you’re absolutely right! Historically, the two components were added separately but to increase efficiency in the kitchen the process was reduced. Unlike baking soda however, the added acid in baking powder identifies it as double acting. It will release CO2 when in solution and at an when in the oven (at an increased temperature).
This then brought to my mind the wondrous powers of yeast. These single-celled microorganisms undergo an oxygen lacking (anaerobic) process called fermentation; the metabolism of sugars into CO2 and an alcoholic component. Its results are similar to the processes above, whereby the evacuated CO2 creates the fluffy and light texture that satisfies our taste buds. A common technique is to set the dough aside to a warm corner of the kitchen. To think about why this is efficient we can apply the phenomenon to ourselves. Personally, when I’m cold my productivity is greatly decreased because my body is literally lacking the energy I need to function! Similarly, these cells require a warm and moist environment to thrive.
As I removed the pastries from the oven, in all of my mouth-watering glory (thank you, salivary glands) my sister looked over and asked me a puzzling question. We had just discussed (and freaked out about) an article we had read about the science behind unboiling an egg. She chuckled as she asked me why I couldn’t “unbake” my pastries. Immediately we discussed how mixing all the components and supplying the batter with heat altered both the chemical and physical composition. She then bit into a cookie, drooled a bit and said, “I wish the batter would spontaneously bake so we wouldn’t have to watch and wait in agonizing hunger”. I then recalled what determines a process to occur naturally (what contributes to its spontaneity), but I decided to save that tangent for another time. My taste buds were eager and my skin was tingling for a taste of that sweet, cream cheese icing. Oh, and I definitely can’t forget the chewy toffee bits that I mixed into my chocolate chip cookies. It was the perfect end to a sweet, science-filled day. Comment below and share your sweet moments in the kitchen! Also, stay tuned for another day in the science of life!
About the Author
Ashnie Badal is a science communicator at IdeaMosaic Inc., a platform with the aims of communicating scientific research and its applications to the general public. She is currently completing a B.Sc in Chemistry at Ryerson University. Along with the desire to increase the accessibility of science, she aims to contribute to ongoing research that continues to drive the species on this planet forward.