Howdy. I first wanted to entitle this post “the perfect chocolate mousse”, but that seemed to claim a little too much, right? Modest as I am, I consider it possible that some people might make even better (or at least equally good) chocolate mousse. But “quite good chocolate mousse” is simply not such a catchy title…
Systematic test of slightly different chocolate mousse recipes. From left to right: 0.5% iota-carrageenan (filled in canister at 80-90°C) | 1% iota-carrageenan (filled at 80-90°C) | 1.5% iota-carrageenan (filled at 80-90°C) | 1% iota-carrageenan (filled at 65°C). Each beaker contains 70g of chocolate mousse.
Modest or not – I felt that the kind of recipe I will present here is perfect for that it gives you maximum flexibility in many respects. More on that later (if you are only interested in a working recipe and don’t want to dig through my concentrated chocolate mousse knowledge, just jump to the end of this post)1.
Chocolate mousse is a long term classic and is made in many different ways, some heavier, some lighter, some more complicated, some simpler2. The most classical mousse au chocolat is mainly a mixture of beaten egg whites and molten chocolate. Alternative recipes create the fluffy texture of the mousse by using whipped cream, or a combination of cream and egg whites. That’s all fine, those recipes are for sure able to produce some delicious chocolate mousses. But apart from having some complications3, I simply like the very modular structure of the recipe I used here. By that I mean that it makes it easy to adjust different properties indepentently, such as intensity, sweetness, level of aeration, and texture.
Let’s start with disappointments first! I will not offer you the ultimate perfect recipe that will suddenly beat all the long-term classics (although I will give you some quite good ones). But what I could do is giving you a perfect kit to your own chocolate mousse. Perfect for four reasons:
1) It is incredibly fast – you can make it in less than 5 minutes.
2) It is very easy4 and pretty foolproof.
3) It is most versatile both in texture and flavor.
4) It is fun to prepare.
I was so happy about all this and about the many chocolate mousses I ate while working on the recipe that it came to me as a shock when I realized a major drawback of the method, which I will discuss at the end of this post. First back to the initial plan. The chocolate mousse formula I was using is fairly simple with the only exception of needing iota-carrageen, probably a not-so-common ingredient in most kitchens5 (and a cream whipper, also not everyone might have at home).
The recipe itself consist of only four basic ingredients (though many more could be added of course):
- Dark chocolate (e.g. 70%) → main flavor source, larger amounts will make the mousse stiffer and heavier
- Additional sugar (or syrup) → to adjust sweetness of recipe to personal taste (can even be left out)
- Liquid (milk, cream, or vegan counterparts) → second flavor source, the more liquid you add, the lighter the taste
- Iota-Carrageenan → gelling agent, no flavor contribution
The liquid is headed on a stove until it nearly starts to simmer (~90°C) and then melt the chopped chocolate in the hot liquid and dissolve both sugar and iota-carrageenan.
While still hot (around 80°C) quickly fill into cream whipper. Charge with gas and shake heavily. Fill in glasses or dishes and cool (you can of course skip the cream whipper step and you will get a chocolate pudding instead of a mousse).
How to play with this recipe
Most of the taste comes from the chocolate itself. The more chocolate you use and the more intense this chocolate is on its own, the more intense the mousse will taste. The dark chocolate character of the mousse can be balanced by the amount of liquid added (the more liquid, the more you dilute the chocolate flavors) and by adding some sugar (or other sweetener). Best taste will only be obtained when using high-quality chocolates.
The texture will depend on several factors. The main contributor to is the iota-carrageenan, more will make it stiffer. But its function depends strongly on the presence of calcium ions, so that the precise amount needs to be adjusted when changing the type of liquid (vegan milk substituted might have different calcium concentrations and could need a little bit more or less iota-carrageenan). To some extent, chocolate will also affect the texture. The more chocolate (and hence the less liquid) the recipe holds, the stiffer and denser/heavier the mousse will be. Further, higher cacao butter content of the chocolate will also make it stiffer.
20-35% Chocolate (60-80% cacao percentage, good quality chocolate of desired flavor profile)
0-10% Sugar (can simply be normal crystal sugar, refined or unrefined)
50-60% Liquid (whole milk, almond milk, hazelnut milk or mixtures of milk and cream to make it more substantial)
0.5-1.5% Iota-carrageenan (iota-carrageenan can be a little hard to get, but it should be one of the best options for this purpose)
Some possible variations:
Adding a little alcohol such as eau de vie or rum (~2-5%).
Using caramel instead of added sugar.
Replace some of the liquid by fruit puree (maybe up to 10% total)
Experimental trials for one type of milk
I tried different ‘milks’, almond, rice, rice-almond, and cow milk, all worked fine. Depending on what type of liquid you use you might have to adjust the amount of iota-carrageenan a little.
I also varied the amount of carrageenan more systematically to better understand its effect and to see how the stiffness relates to the flavor perception.
I made four nearly identical test batches with
- 60g dark chocolate (62% cocoa)
- 10g sugar (half-refined)
- 130g rice-almond milk (from Provamel)
- 1g-3g of iota-carrageenan (Kalys), corresponding to 0.5-1.5%.
After heating and mixing I filled it into a 0.5liter cream whipper (isi whip), charged it with one N2O charger and filled it into glasses before cooling it down for 30 minutes in a fridge. It very quickly becomes obvious that both the volume and the stiffness change with higher iota-carrageenan concentrations. The mousse is a little less fluffy and also thickens much faster. I fucked up one batch by waiting too long before charging+shaking+foaming it, so that it had cooled to 60-65°C and while shaking it already partially thickened in the whipping canister. I could get out less than half of the total mixture and it was denser, too.
Following my adoration for numbers I also tried to quantify those effects (see the graph below!) and so I measured the elastic modulus, which is a physical quantity that tells you how much a material deforms if you put a certain weight on it. To get a feel for the numbers: 700 – 2000Pa (=”Pascal”) is pretty soft. Gummy bears have around 70,000Pa. Anyway, it’s not so much the precise numbers6 but the relative difference between them that is interesting here. It clearly shows that the changes in iota-carrageen change the mousse texture quite a bit.
Putting weights on chocolate mousse was already quite entertaining, but -guess what- it was even better to finally have a quick tasting of the different mousses. With a scientifically sound group of people (n=2) we tested the mousses and the outcome surprised me a lot. Although the flavor contributing ingredients were identical, the soft mousse tasted much sweeter and less intense! In the end we agreed on 1% iota-carrageenan as our favorite, so one could put an end to this chocolate mousse testing… but no…
Two things keep me thinking.
First, I now really keep thinking that I want to repeat this on a bigger scale (I fear that’s the scientist in me). And second, I read a great article by Chris Ying in Lucky Peach7 that had a look at the carbon dioxide footprint of eating at home versus in different restaurants. I felt stupid when I read what he had to say about using N2O charged cream whippers. How comes that I never thought about that before? Anyway, N2O of course happens to be a very powerful greenhouse gas8. Sad, but that makes the dish less sustainable than I hoped for (e.g. by replacing eggs and cow milk against plant based alternatives). That means I clearly have to look at other ways to aerate the mixture. I’ll let you know.
- To be more modest: the recipe(s) I give here are not completely based on own ideas. You will find quite a number of similar recipes in the net. [↩]
- There are soooo many chocolate mousse recipes out there. Here is a another comparision. [↩]
- Using raw egg to make the beaten egg whites is a concern to some. In addition, some of the more sophisticated recipes can be a little time consuming (not overly complicated, though). [↩]
- It really IS easy, except that it needs to non-standard tools and ingredients: a cream whipper and iota-carrageenan. [↩]
- Carrageenan is a polysaccharide from seaweed (polysaccharide means it is a very long chain of sugar-like molecules, in principle not so different from starches). The most common forms used in food are kappa-carrageenan which can make very stiff gels, and iota-carrageenan, which makes softer, elastic gels. [↩]
- Actually the numbers are also not constant. I measured them about 1 hour after preparing the chocolate mousse. But the mousse noticeably hardens over time, especially if you keep it in the fridge for longer -say- overnight. [↩]
- The article “Knowing is half the battle” by Chris Ying came out in “guts” a part of the Lucky Peach Fall 2013 issue. It contains a lot of interesting thoughts on sustainability in food preparation at home or in restaurants. I especially liked his proposition to aim at more sustainable restaurants and to make them noticeably more sustainable than cooking at home (which right now is most often not the case, but clearly could be done!). [↩]
- N2O is considered to have an about 300 times higher impact on global warming than CO2, so that every charges I use corresponds to roughly 3kg of CO2. [↩]