Science & Cooking - chemistry through the medium of food

The last couple of weeks I’ve been baking sponge cakes using my favourite recipe, keeping everything the same, except for how long I whisk the batter. When I’ve cooked and cooled the cake, I’ve measured it’s height, cut sections out and put a weight on them to measure compression. Why?

I’m participating in Science & Cooking, an edX online course delivered by Harvard. It is basically chemistry, and I’m delighted to recognise a number of the equations we use, if hazily, from my school days. But because it’s chemistry as applied to cooking, I’m paying attention in a way I didn’t at school. (Saying that, when we studied emulsions and our teacher asked for an example of such a substance, I put my hand up and offered mayonnaise. Even back then, I learned through cooking.)

The course starts gently, with molecules and densities, and moves on to look at heat dispersion, diffusion, elasticity, foams and emulsions and a number of other topics. Each week, a particular equation is discussed and taken through its paces. The teaching element consists of a number of videos, as well as reading (most of it optional), quizzes and, most importantly, labs and homework. Each week we get a new recipe to try, either as an integral part of the lab, or as an example of a point discussed by the homework. I haven’t made all the recipes – you don’t have to – but I have done all the labs and homework. The course takes up to eight hours a week, if you do the homework, labs and suggested reading. I’m enjoying Harold McGee’s On Food and Cooking tremendously. Yes, there’s a lot of art in cooking, but there’s a lot of science too.

Heat diffusing the perfect egg. (The labs use a lot of eggs.)

It’s been a really interesting experience, both from an online learning perspective and a cooking perspective. If I wanted to, I could pay for a certificate, but am happy to operate on the ‘honor code’ – there will be no evidence that I took and passed this course. I’m doing it entirely for fun, after all, it has no relevance to my day job or future employment.

Final project

The task I’m working on now is the final project, a larger piece of work where we look at a particular recipe to learn why it works the way it does. We then submit a lab report for credits. I’m investigating what makes my favourite sponge cake rise, and if there is an optimum protocol for making it. It’s interesting because it doesn’t use a leavener so the art is in maximizing the amount of air whipped into the batter.

I have one more cake to bake, with an all new protocol (emulsion + foam = ?), and then I should be able to draw conclusions. I’m submitting my project at the end of the week. Wish me luck! Meanwhile, here’s the original recipe for the cake, if you want to try it out and form your own opinion of the best way to make it rise, and why the top is crunchy.

Easy to make, easy to eat.

Air-leavened sponge cake

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Preparation time

10 mins

Cooking time

45 mins

Total time

55 mins

This is the cake my mother taught me to make. It is simple to make and can be varied in a number of ways. It is not a very high cake but tends to have a somewhat dense crumb, and should have a thin layer of crunchy crust on the top.

Author: Edinburgh Foody

Recipe type: Cake

Cuisine: Swedish

Serves: 8

Ingredients

3 medium eggs
300 ml caster sugar
50 grams butter, melted
300 ml flour

Instructions

Pre-heat the oven to 175C (160C fan).
Butter a 23 cm cake tin.
Put the eggs and sugar in a bowl and whisk until pale and fluffy (about 3 minutes with an electric whisk at maximum speed).
Pour in the melted butter and the flour, and fold in, taking care not to lose too much air.
When completely incorporated, pour the batter into the cake tin.
Cook in the middle of the oven for 40-45 minutes.
Let cool completely before cutting (about 1 hour).