The trick to good chocolate
Creating glossy, snappy chocolate that melts slowly on the tongue takes work. If you melt it and leave it at room temperature, it won’t set. Popping it in the fridge results in a fleeting firmness; as soon as it’s back on the counter, blotchy and dull, it starts to soften.
“Well-tempered chocolate is necessary for high-quality chocolate,” says food material scientist Dr. Alejandro Marangoni.
For Marangoni, who strives to understand the behaviour of each of the components in food, tempering chocolate as it transitions from liquid to solid has been a long-standing problem. But he and a team of University of Guelph researchers have found a shortcut.
“Bad tempering leads to the wrong texture and melting point, but it’s also a precursor for blooming: when your chocolate goes white on the surface. A lot of the problems of chocolate quality are related to improper tempering,” says the professor, Canada Research Chair and lead author of a paper published in Nature Communications demonstrating how, by adding a minor component of cocoa butter, customary techniques could be bypassed.
There are many ways to temper chocolate, requiring adherence to specific temperatures for melting, cooling and using (all with different targets for dark, milk, and white or ruby chocolate). As pastry chef Julien Merceron wrote in À la Mère de Famille, “the art of the chocolatier is not one that can be improvised.”
Picture a chocolatier in their chef’s whites, repeatedly spreading and scraping melted chocolate on a marble countertop. This tempering method, called tabling, is perhaps the most recognizable of all: After melting the chocolate in a bain marie (hot water bath), the chocolatier pours most of it onto the marble, agitating it as it cools and thickens before marrying it with the remaining melted chocolate, continually stirring to “seed” it.
The success or failure of the batch rests in the hands of the maker; their ability to read the chocolate is as essential as heeding a thermometer reading.
“It all relies on the experience of the chocolatier, and it’s not 100 per cent. They can make a mistake and the chocolate can be under-tempered or over-tempered. And then once you make the chocolate and it’s finished, it’s very difficult to get it back. So that’s a wasted batch,” says Marangoni. “Now imagine trying to reproduce that thing industrially. You can’t have a whole bunch of cooks scraping marble slabs.”
In large-scale manufacturing, melted chocolate is pumped into tempering units three storeys high, where it’s cooled, sheared (mixed), heated up and cooled again, all in an effort to create the right crystal form. When cocoa butter solidifies, it can form six types of crystals. Preferred for its desired melting point, snap and gloss, the form V crystal is created during the tempering process.
“You have to do all this hullabaloo that the chocolatier does in order to get to that form. It’s difficult to get to that form easily,” adds Marangoni. “So our motivation is to try to reproduce tempering, but in a more reproducible way without the use of these complex cooling and heating procedures.”
As in the tabling method, tempering often involves seeding melted chocolate with chocolate already in temper. The seed provides a template, encouraging loose cocoa butter crystals to get in formation. This results in a stable, shiny product that breaks cleanly and melts in your mouth (not in your hands).
Marangoni and his research associate Dr. Saeed Ghazani, master of science student Jarvis Stobbs and chemistry student Jay Chen took this concept of a templating seed of chocolate to a micro level. In a world first, instead of using chunks of chocolate in temper, they found that by adding a saturated phospholipid naturally present in cocoa butter, they could achieve the desired structure.
“This was (a way) to take out the mystery a little bit. And we were lucky enough to discover that one family of these minor lipids did the job of tempering the cocoa butter really well,” says Marangoni.
To confirm the effect of their ingredient on structure, the researchers imaged chunks of chocolate at the University of Saskatchewan’s Canadian Light Source, where Stobbs is a beam line scientist.
“You can see the whole microstructure,” explains Marangoni. “Tempering goes all the way up to millimetres you can see with the eyeball. So you can go from X-ray diffraction, which is molecular size — and everybody focuses there — but the microstructure of the chocolate is super important, too. And that’s what we eventually experience with our hands … that snap and gloss is related to an upper-level of structure.”
Their simplified process eliminates the need for expensive machinery, which could change the industry. Large manufacturers could use it in tandem with tempering units “as an insurance policy,” but Marangoni sees it as being more beneficial for smallto medium-sized producers who would no longer be constrained by the capacity, speed or capital investment of machinery.
Their findings could also offer an opportunity for manufacturers to improve their carbon footprint, Marangoni adds. Food production contributes one-quarter of the world’s greenhouse gas emissions, according to Our World in Data, and he sees this work as part of a larger initiative to increase sustainability and decrease energy costs for industrial processes in manufacturing.
Most research in the area has focused on the main component of cocoa butter — fat molecules called triglycerides, which can vary country-to-country, depending on where the cacao was grown. In contrast, the research team set their sights on the remaining four per cent — the minor components — and questioned their role in tempering.
By removing these minor components and adding them back, one by one, they not only were able to catalogue what they do, but discovered that phospholipids have “a huge effect” on crystallization.
“An addition of even just 0.1 per cent templates the whole crystallization process of cocoa butter into the right crystal form and crystal size,” says Marangoni. “We were like, ‘Oh my God, we do not need to do this white hat, marble table, tempering procedure.’ Just by adding sufficient amounts of this specific phospholipid, which was part of the natural milieu of minor components, we can get there.”
THE ART OF THE CHOCOLATIER (CANNOT) BE IMPROVISED.