Macarons au chocolate & cocoa butter polymorphism 🍫

Hello, dear reader ☺️ Thanks for stopping by! I take it you’re here to learn more about how the fat in chocolate behaves and/or making chocolate macarons? Either way, I hope it’s chocolate-related, or you may be overwhelmingly disappointed… ?

It’s been an interesting several months for me… I’ve somehow managed to achieve and move forward with a lot whilst also being incredibly unproductive and scatty. I had written in previous draft blog posts last summer that I’ve been feeling ‘lost’ for a couple of years now (since finishing my PhD, really). I think that’ll be a topic for another blog post. But particularly over these last several months I’ve been lacking structure and have had my fingers in far too many pies (#firstworldproblems, amirite?). So I thought I’d use this as an opportunity to revisit an old and faithful love… chocolate! ??

? Cocoa butter polymorphism presentation
? L’Art de la Pâtisserie et le Chocolat (Chemistry World essay)
? How to make chocolate macarons!

Cocoa butter polymorphism presentation

In my last blog post I shared the video of me speaking in front of over 200 people on a stage at the finals of the IET’s PATW competition in 2016 whilst seeing myself projected on large screens, shined on with many lights, and even hearing my voice over a large sound system. I even got a message from someone I knew 10 years or so ago saying, ‘that’s not the shy Charlotte I know!’ Now, if I mention shyness to people, I’m met with, ‘you’re not shy!’ It’s a great acknowledgement to me of how far I’ve come over the past 12 years ?

As soon as I saw the poster for the competition I initially thought that I’d enter the local (first) round of the competition at the university (literally a few buildings away on campus) in order to practice my speaking skills. I’ve always struggled with public speaking, in particular, speaking on the fly and coming off as looking comfortable in front of an audience. And so I thought that this was a non-threatening way in which I could practice. It turned out that there was someone in the audience I knew! And, I even invited my parents to come and watch. And I actually made it through that round! Then I was coached by two wonderful people who helped me to bring out my speaking skills and refine my chocolate story more, and I made it through the regional, national, and to the global finals, all completely unexpectedly!

Anyway, I was able to put the presentation together at relatively short notice because I had an idea of what I wanted to say from having done a lot of research about pastry and the science behind meringue, chocolate, puff pastry, etc., in order to prepare for writing an entry for the Chemistry World’s Science Communication Competition in 2014, which you can see below:

Left: the Chemistry World’s Science Communication Competition finals required a physical presentation of the topic of our essays (of course, that meant lots of baking!). Right: an article published in New Food Magazine thanks to all of the chocolate knowledge I managed to obtain after all that reading around I’d done over the years! ???

I also wrote a technical article for New Food Magazine after the PATW competition, and am so honoured that it was published in their confectionary piece ??

L’Art de la Pâtisserie et le Chocolat
Chemistry World science communication competition essay 2014-15

“He succeeded… in raising pâtisserie to the rank of art¹,” is what was said of Gaston Lenôtre by ex-President Nicolas Sarkozy. Lenôtre left his mark by incorporating tropical flavours such as kiwi, guava, and mango into his creations, and has trained many of the best-known names in gastronomy that we know today. Sadaharu Aoki also combines exotic essences from his home country Japan, such as matcha and yuzu, into his ultra-modern sweets. Pierre Hermé, a former disciple of Lenôtre, was labelled by Vogue magazine as the ‘Picasso of pastry²,’ and dedicates runway shows to his seasonal confectionaries.

Left: Homemade matcha macarons with dark chocolate or strawberry ganache.
Right: Bamboo entremets: layers of biscuit joconde, crème au thé vert, ganache au chocolat noir, punch au thé vert (altering layers of matcha-infused buttercream, dark chocolate ganache, and biscuit sponge), Sadaharu Aoki, 35 Rue de Vaugirard, 75006 Paris, France.

Food and art have always gone hand-in-hand, and chemical principles underlie not only the development of the industry, but also the way in which gastronomic delicacies are presented. A prominent example would be Louis Pasteur, a French biochemist who, in around 1856, discovered that heating, or pasteurising, raw milk increases its longevity and destroys harmful bacteria. This made it safe for human consumption because it prevented the multiplication of microorganisms. The same is true of fruit juice, beer, and wine, thus salvaging the French wine industry.^{3, 4}

Marie-Antoine Carême (1784-1833) was the first to incorporate art into French cuisine; inspired by the architecture of ancient ruins, he designed intricate centrepieces of nougat, pastry, and marzipan.⁵ He was the personal chef to many famous historical figures, including Napoléon, whose wedding cake was constructed by Carême. This ‘Napoléon cake’ is still a popular French dessert today, and is known as a mille-feuille.^6,7 Carême was also the first to pipe meringue, a delicacy of which Marie Antoinette was very fond, into shapes using a pastry bag.⁸

Louis-Ernest Ladurée combined pastry with coffee, and opened Paris’ first salon de thé, Ladurée, in 1871. Jules Chéret designed the interior, and took his inspiration from the Sistine Chapel and the Palais Garnier.⁹ Pierre Desfontaines, grandson of Ladurée, claims to have invented the modern macaron in 1930.¹⁰ A macaron is two meringue biscuits sandwiching a rich and velvety filling, usually a ganache, and those of Ladurée are some of the best in the world, rivalled by few. Except for Pierre Hermé, perhaps. Because macarons are highly stylish and trendy, they undergo rigorous scrutiny by professionals, as their quality gives insight into their creators’ craftsmanship.

Above: A selection of pâtisserie from Ladurée, 21 Rue Bonaparte, 75006 Paris, France.
Below: Sampling the exquisite caramels and mille-feuille à la vanille, Jacques Genin, 133 Rue de Turenne, 75003 Paris.

Meringue is made by vigorously beating egg whites to unravel chains of amino acids, or proteins, called ovalbumin. This mechanically denatures them, causing their partial coagulation via stereometric changes¹¹, and incorporates air into the mixture. Polyvalent cations form strong complexes with a different egg white protein called ovotransferrin, which increases the meringue’s heat stability. Cu²⁺ is generally the most effective cation11, and so most pastry chefs will whip egg whites in a copper bowl. Sugar is then gradually added to increase the viscosity of lamellar water¹², thereby better stabilising the foam. When the meringue is baked, the air bubbles expand giving the meringue greater volume.⁹

Chocolate is another material utilised by artists throughout the world. Patrick Roger is a master French chocolatier, and a visit to his laboratory would reveal monumental chocolate sculptures, some weighing in at 80 kilos, and hundreds of beautifully crafted, colourful bonbons all neatly lined in metre-long gift boxes.¹³ Only knowledge of chocolate’s intricate chemistry is able to produce such celestial pleasure from the bitter cocoa bean.¹⁴

In 1879, Rodolphe Lindt of Switzerland produced the first dark chocolate via a mechanical treatment step known as conching.¹⁵ Conching grinds the solid cocoa bean particles in liquid chocolate to a size below 20µm, which creates a silky mouth-feel. The increase in surface area also allows flavour compounds to diffuse into the surrounding cocoa butter, the main ingredient in chocolate, thus intensifying the flavour.¹⁴ Lindt did wonders for the chocolate industry.

Left: Homemade matcha macarons with dark chocolate or strawberry ganache.
Right: A dégustation of chocolates, Jacques Genin, 133 Rue de Turenne, 75003 Paris..

Willie and Lutton, in 1966¹⁶, identified six crystalline states of cocoa butter, I-VI, largely by x-ray diffraction; polymorph V has the most pleasant mouth-feel, a nice “snap” sound when broken, and prevents fat bloom. Chocolatiers use tempering, a controlled pre-crystallisation technique, to form this polymorph, and involves slowly cooling melted chocolate. This aids in creating nucleation sites for the cocoa butter to form small, regularly sized crystals, i.e. polymorph V. Fat bloom, which is where chocolate appears mouldy, is a sign of poor tempering. It happens due to partial melting of the cocoa butter, which causes it to rise to the surface. Many hypotheses attribute the kinetics of fat migration in the particulate structure of chocolate to diffusion and capillary processes; the actual mechanism, however, is still unclear.¹⁸

The art of pâtisserie, chocolat, and cuisine in general are perfected by few, but savoured by many. The key determiner of the quality is ultimately the extent of understanding of the underpinning chemical principles. It’s the accumulation of this knowledge, acquired through generations, that has lead to the striking visual masterpieces that we enjoy today.

Left: A beautifully flaky pain au chocolat from Liberté, 39 Rue des Vinaigriers, 75010, Paris, France.
Right: Sampling the artisanal Beurre Bordier and red wine at L’Avant Comptoir, 3 Carrefour de l’Odéon, 75006 Paris, France.

References

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How to make chocolate macarons!
This section was first published on my old blog on 1^st Jan 2014 ?

Perhaps I’ve finally mastered the recipe and got to grips with my oven?! Or perhaps not… just because I’ve made decent looking macarons a couple of times doesn’t mean a thing! Especially as on a more recent attempt, they failed completely.

I ran out of icing sugar, and used desiccated coconut in place of the almonds. When I baked the cookies, they developed no foot at all, and had a completely different texture to regular macaron shells. However, I still sandwiched them with the chocolate ganache and put them forward in the badminton league buffet. I did get compliments though, as they were quite tasty, although nothing like the macaron I was hoping for!

There are many variations of making macarons posted all over the internet; some people try it and have great success, while others try and have little. Sometimes it’s just that the instructions can be quite ambiguous. When a recipe states something along the lines of “now, incorporate the almonds and icing sugar with the egg whites, being sure not to over mix. You know that you’ve over mixed when the batter is dull,” it can mean anything! But for me, the most important part of making macarons was the “macaronage,” which some people use to refer to the part where the almonds and icing sugar are incorporated into the egg whites, and the right amount of air is knocked out of the whites. If the batter is over mixed it will become very runny, and won’t be able to hold its shape when piped. However, if it’s under mixed, you won’t get a perfectly smooth shell and too many air bubbles inside. The piped macaron shells are then left on the worktop for about an hour to air-dry. This helps to create a hard shell, so that when the air inside of the macaron shell expands in the oven, the shell is forced upwards thus creating the “foot” at the bottom. If the shell isn’t tough enough, then it’ll crack and no foot will develop. I have read on a few other blogs that leaving them out to “air-dry” wasn’t a necessity for them, but in my experience, is it a necessity for me!

The following video is a great instructional video on how to make macarons. The part about knocking the air out of the egg whites was what I found the most helpful: if you plop some of your batter onto a plate before baking, and the peak slowly disappears, then you’ve got the perfect batter. It should have a “magma” like consistency. I found that to be a top tip!

I use a roasting tin with parchment paper to bake my macarons, because it doesn’t distort with the heat of the oven, therefore giving lopsided shells. Also, I place the roasting pan on top of a broiler pan in the lower part of my oven. This stops the heat from the bottom of the oven being too harsh on the shells, and also keeps the macarons perfectly at mid/lower-level in my oven! However, I can only bake about a maximum of 12 shells at a time. So macaron baking requires patience!

The temperature at which people bake their macarons is also a hot topic. Too low or too high temperatures result in undesirable consequences, which is why it’s important to “get-to-know” your oven. A further note is that the size of the macaron shell I believe is entirely of your choice, as I’ve seen and bought macarons of varying sizes. Some like them rather large but other prefer them bite-size. Personally, I prefer slightly larger maracons, that require two or three minute bites. But that’s just me. ?

And finally, macarons do taste better with time, which probably goes against almost all rules of French pâtisserie! But I suppose that as macarons aren’t pastry, the rules of pastry don’t apply. It takes time for the shells to absorb the flavour of the ganache, which gives them a very soft and flavourful interior. Some people recommend eating them after 2 days, but the ones that I bought from Zürich airport (along with other sources) suggested up to 5 days for maximum flavour. In fact, the blog Not So Humble Pie suggests that if you’re leaning towards either over or under-baking your macarons, go towards over-baking them, because if they’re a little too dry, the moistness from the ganache can help to rectify the issue after a few days of mingling!

A great trouble-shooting guide, as well as other tips and discussions, can be found here.

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Macarons au Chocolat
Adapted from: Not So Humble Pie and Kokken 69
Makes 8-10 shells (4-5 macarons)

Ingredients
For the shells:
• lemon juice
• 40g ground almonds
• 57g icing sugar
• 10g cocoa powder (or replace with icing sugar and add some vanilla essence instead)
• 35g egg whites
• 11g granulated sugar

For the ganache: (enough for about 15-20 macarons!)
• 200g dark chocolate, broken into pieces
• 200g double cream
• 70g butter, at room temperature

Preparation
For the shells:
Add a splash of lemon juice to a very clean bowl together with the egg whites. Whisk for about 30-60 seconds until very frothy. Sprinkle in the granulated sugar, and continue to whisk until stiff, glossy peaks form (the kind where you can hold the bowl upside down over your head!).

Then sieve in the icing sugar, cocoa powder and ground almonds together over the egg white peaks. Now, this is the part some people refer to as “macaronage” (i.e. macaron-ing). Use a wooden spoon or pastry scraper to knock the air out of the batter. Use the spoon to scoop the batter around the outer edges of the interior of the bowl and then almost scrape the batter down the middle of the bowl in a zig-zag pattern until the final consistency is similar to that of magma. A useful video to watch can be found here.

A test to see if the batter is of the appropriate magma-like consistency is to take a clean plate, and dollop a spoonful in the middle. If the peak slowly disappears into itself, then the batter is ready. If it’s still visible after about 30 seconds or so, then it needs some more air knocking out! If the batter is too runny, then you’ve over mixed!

Prepare a heavy-duty baking sheet with baking parchment. Spoon the batter into your piping bag (or icing syringe, etc.), and dollop macarons onto the parchment paper, leaving at least an inch worth of space between each shell. This depends entirely on how large you want your macarons.

Bash the tray on the surface of the worktop 4 times, rotating each time. This forces air bubbles in the macaron batter to rise to the top. Use a toothpick to pop any large ones. Leave the macarons on the side for an hour to air dry, so that they’re not sticky or tacky to a light touch.

Preheat the oven to 155◦C, ensuring that you do not use fan assist. Pop the tray into the lower half of the oven for 16-18 minutes.

Leave to cool completely before peeling the shells off the parchment.

For the ganache:
Melt the chocolate and cream over a low heat in a saucepan; allow to cool to around 50^◦C. Cut up the butter in a bowl, pour over the chocolate sauce, and whip until smooth. Pop into the fridge until thick enough to pipe. Before piping, leave the bowl out of the fridge for a while to bring the ganache up to room temperature.

Assembling the macaron:
Fill an icing syringe or piping bag with the ganache, and dollop a splodge into the centre of a macaron shell; not too much or too little. It takes a little practice to get the right amount, so that when the two shells are sandwiched together, the ganache spreads to the edges of the shell but no farther, and so that there’s a smooth, unblemished edge around the ganache. Pop in the fridge for anywhere between 2-5 days before taking out of the fridge to bring it up to room temperature before devouring. ?

Shells baked: 19.12.2011, shells filled: 20.12.2011.
Bon appétit!!

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Essay references
1. Levy, P. (2009) ‘Gaston Lenotre: Pastry chef who brought patisserie into the modern age.’ The Independent, accessed 13.12.2014
2. Westley, H. (2007) ‘The tasty history of Parisian patisseries.’ Expatica, accessed 13.12.2014
3. Haas, L. (1998) ‘Louis Pasteur (1822-95).’ Journal of Neurology Neurosurgery & Psychiatry, 64 (3). Pp 330
4. Licciardello, F., Frisullo, P., Laverse, J. Muratore, G. & Del Nobile, M. A. (2012) ‘Effect of sugar, citric acid and egg white type on the microstructural and mechanical properties of meringues.’ Journal of Food Engineering, 108 (3). Pp 453-462
5. Hyman, M. & Hyman, P. (2003) ‘Carême, Marie Antoine.’ Encyclopedia of Food and Culture, accessed 13.12.2014
6. Kelly, I. (2003) ‘Crème du Carême.’ The Guardian, accessed 13.12.2014
7. French Gourmet Blog (2011) ‘Marie-Antoine Carême, First Celebrity Chef.’ French Gourmet Hong Kong, accessed 13.12.2014
8. Jackson, K. L. & Gardner, J. E. (2012) ‘Meringue.’ Gibbs M. Smith Inc.
9. Ladurée Paris ‘The History Of Ladurée House’ (accessed 13.12.2014)
10. Levin, R. (2014) ‘Talking macarons and more with Laduree’s Pierre Antoine Raberin.’ amNY, accessed 25.12.2014
11. Bovošková, H. & Míková, H. (2011) ‘Factors influencing egg white foam quality.’ Czech Journal of Food Sciences, 29 (4). Pp 322-327
12. Lau, C. K. & Dickinson, E. (2005) ‘Instability and structural change in an aerated system containing egg albumen and invert sugar.’ Food Hydrocolloids, 19 (1). Pp 111-121
13. Roger, P. (2014) ‘Patrick Roger, chocolate artist.’ Patrick Roger, accessed 13.12.2014
14. Roth, K. (2005) ‘Von Vollmilch bis Bitter, edelste Polymorphie.’ Chemie in unserer Zeit, 39 (6), translated by Kortenjann M. and accessed 13.12.2014
15. Vera, R. (2013) ‘The history and science of chocolate.’ The Malaysian Journal of Pathology, 35 (2). Pp 111-121.
16. Willie, R.L. & Lutton, E. S. (1966) ‘Polymorphism of cocoa butter.’ Journal of the American Oil Chemists Society, 43 (8). Pp 491-496.
17. Afoakwa, E. O., Paterson A., Fowler, M. & Vieira, J. (2008) ‘Effects of tempering and fat crystallisation behaviour on microstructure, mechanical properties and appearance in dark chocolate systems.’ Journal of Food Engineering, 89 (2). Pp 128-136
18. Afoakwa, E.O., Paterson, A., Fowler, M. & Vieira, J. (2009) ‘Fat bloom development and structure-appearance relationships during storage of under-tempered dark chocolates.’ Journal of Food Engineering, 91 (4). Pp 571-581

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