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You don’t really understand food and recipes, until you’ve tried them. At least, that is my opinion. Once you’ve tried something a few times, it starts making more sense.
This strawberry mousse mirror cake covers several learning points which we’ll walk through briefly today. It sort of is a science project, although what you can make is really there to eat! The cake is really a more advanced cake to make, but tastes as if it comes fresh from a bakery, so definitely worth your effort!
This cake is made up of three components:
- A light airy cake, pretty similar to one used for Swiss rolls
- A strawberry mousse
- A translucent strawberry mirror glaze
Each of them is full of science. How you make them involves a lot of chemistry & physics: gelling of a glaze, denaturation of proteins in a cake, aeration of a mousse. And don’t forget the ingredients themselves, the red in strawberry and the proteins in egg! If you just want to make the cake you might as well start scrolling down to get the recipes. If you would like to see some great cake science, continue reading!
A light cake
This cake will be covered with a strawberry mousse that is full of fat and cream. Therefore, the cake itself is actually quite light. It doesn’t contain any fat, apart from the fat that is present in the eggs you use.
By not using as much fat you are able to create a very light and airy cake. Normally, fat tends to push down a cake and make it more dense (for example in a pound cake). Now that we don’t have much fat we don’t have to use baking powder to help it puff somewhat. Instead, we whip up egg whites and fold those into the batter. The egg whites lighten up the cake even before it goes into the oven.
A rich & airy strawberry mousse
Strawberries are very different fruits than let’s say a banana. It would be pretty hard to make a light and airy banana foam after you’ve removed most of its loose moisture (as we do in this recipe). Not so for stawberries. Bananas contain a lot of fiber which thickens up a mixture quite easily. Strawberries on the other hand have a lot less fiber. It is more sugar & water. What’s more, once you puree a strawberry the remainders turn liquid quite easily as well. Making them perfect for this mousse!
To make a mousse we use two other components: an anglaise & a whipped cream. The anglaise provides richness to the foam and helps thicken the strawberry puree. You will often see anglaises used for making ice cream!
An anglaise is not airy though! That is why you add in a whipped cream. Cream with a high fat content is exceptionally suited for aeration. All the fat in the cream will hold on to all the air bubbles as you whisk the cream. Heat on the other hand can destroy the foam again, making the whipped cream collapse. That is why in the recipe you will need to cool down the anglaise first, before gently mixing it with the whipped cream!
A bright red strawberry mirror glaze
The cake has a translucent, bright red strawberry mirror glaze. This cake though does not contain any added colouring. All the colours come from frozen strawberries!
Remember our extensive analysis of the colour red and the colour of red cabbage? Remember that group of molecules called anthocyanins that are responsible for a whole array of purples, reds and blues? It’s those molecules that give the strawberry it’s bright red colour. In strawberries as much as 25 different anthocyanins have been found. Together creating that beautiful colour.
Acidic strawberries & lemon juice
The colour of anthocyanins depends a lot on the pH-value (a measure for acidity) of their environment. They are red at lower pH-values (more acidic). You might think strawberries aren’t sour, however, take away their sugar and you will realize they are indeed acidic. Once you transform that strawberry into strawberry puree & liquid, you will notice that the liquid actually tastes sour!
To help the red colour a little more, we also add some lemon juice to the glaze. Lemon juice is very acidic and will help bring that pH-value down and brighten the strawberry red!
Understanding mirror glazes
We’ve discussed mirror glazes quite extensively before. Mirror glazes are made with gelatin which helps them to set and helps make them beautifully nice and shiny. If you read those articles, you should be all set to go for this strawberry glaze!
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Lopes da Silva, F., et. al., Anthocyanin pigments in strawberries, 2007, link ; great article if you want to know exactly which anthocyanin molecules sit in strawberries