Introduction: Scientific Lemon Mousse

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I usually do not use an apron and kitchen utensils, I rather be in my small garage and surrounded by other tools and electronic equipments.

Recently I´ve learned about this recipe and I became fascinated.

All you need is milk cream and a few lemons the rest is science. I did this dessert once and was amazed, because I wasn´t expecting it to look so nice and solid.

Get ready to learn how to create a great Lemon Mousse that despite being simple involves a very interesting chemistry.

Let´s start!

Step 1: Ingredients & Utensils:

Ready in: 2 hours.

Strain in refrigerator: 1 hour.

Serves: 6 portions.


  • 400ml Whipping Cream;
  • 300ml Condensed Milk;
  • 4 or 5 Lemons;
  • 6 Cookies;


  • Electric Hand Mixer;
  • Juicer;
  • Electric Blender;
  • Mixing bowl.


If you prefer the mousse less acid you can put less lemons, but for that you have to leave the mousse more time in the refrigerator.

Step 2: Instructions:

  1. Add 400ml of whipping cream with 300ml condesed milk in the mixing bowl. Mix everything very well with a spoon until it is a homogenous mixture.

  2. Prepare the lemon juice with all the lemons, use a Juicer for it. After completing confirm that the juice does not contain lumps.

  3. Whisk the cream with the electric hand mixer and slowly pour the lemon juice into the bowl. Science happens now! You will notice that the mixture is becoming thicker. Continue to whisk the mixture until it becomes solid.

  4. Pour the mousse into a bowl ready to serve. Straight the surface with a spoon and let it rest for a while.

  5. Crush the cookies with the Electric Blender until they are completly granulated.

  6. Gently place the crushed cookies on top of the mousse using a spoon.

  7. Last of all put the mousse in the refrigerator for an hour so it becomes cool and solid.

Serve and Enjoy!

Step 3: Scientific Explanation:

Let's reveal what happend during the making of this mousse (French term), when two liquids became a light and fluffy foam. If you remember, we used two main reagents, whipping cream and condesed milk, which derived from milk, and another reagent which is lemon juice.

These reagents are aqueous solutions. The whipping cream and condesed milk are composed of molecules of lactose, fats and proteins (Milk), which have almost a neutral PH. Both are concentrated, because 60% of the water have been removed. In the case of the condensed milk it has a big amount of sugar, about 44%.

The other reagent, the lemon juice is also an aqueous solution. Mainly composed of citric acid, so it has an acid PH.

Why do you use whipping cream and condesed milk instead of milk?

Well, to create a firm foam it is necessary that the liquid has some viscosity. Otherwise, with normal milk the air bubbles produced by the electric hand mixer would dissipate quicker than with the whipping cream.

When the lemon juice is mixed with the cream, these becomes much thicker, lighter and fluffier. This occurs because the Lemon Juice's acid provokes a chemical reaction with the Casein, which is the major protein in the milk (80%).

This happens, because changing the PH of the milk (neutral) to acid PH it reaches the isoelectric point and begins to coagulate the casein protein. It transforms into a gel, which turns the milk into a light and fluffy foam.

Voilá our Mousse is done.

Science of Cooking

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Science of Cooking