Chocolat is one of my all time favourite books, the movie is great too. There’s a lot of science in the making of chocolate. Let’s start by looking at some recent science.
What makes a good chocolate?
In May 2019, Professor Wilson Poon from the University of Edinburgh’s School of Physics and Astronomy published his team’s findings on what makes a chocolate good chocolate. The research team, collaborating with researchers from New York University studied a process called ‘conching’. Conching was invented by Rodolphe Lindt in 1879.
Like a lot of scientific discoveries, his invention was a matter of serendipity after many many failed attempts. At the time, chocolate was not very easy to eat, and had to be chewed thoroughly to release its deliciousness. Lindt discovered that the ideal chocolate texture could be achieved after hours of mixing the ingredients which combine together to give us chocolate as we know it today. Perhaps Willy Wonka was onto a good thing when he said ‘No other factory in the world mixes its chocolate by waterfall…But it’s the only way if you want it just right.’
Mixing and rich glossy textures
Many factors were considered in Professor Poon’s study, and these included the density of mixtures and the manner in which fluids flow during different stages of the mixing process. The scientists also looked at how the continuous mixing changed the physical properties of the solid ingredients that comprise chocolate, like sugar, cocoa butter, and cocoa. Anybody who has had to cream butter and sugar together as one of the preliminary steps in home baking will attest to that moment of profound satisfaction, when after mixing, for what seems like hours, the mixture suddenly ‘comes together’, into a smooth, rich glossy texture.
We’re spoilt for choice
Chocolate comes in a variety of flavours, and we’re spoilt for choice. Some chocolates are also inextricably linked with their country of origin, like our iconic Peppermint Crisp chocolate. In January 2019, there was mild panic on Twitter when rumours abounded that this South African staple was to be discontinued, but BusinessTech calmed us when it told us that Nestlé had no plans to discontinue this much loved confectionary. Peppermint Crisp may not be the best selling chocolate in South Africa, but it is a favourite.
Bestselling chocolates in SA
According to BusinessTech, in South Africa, the bestselling chocolates are; from Mondelēz South Africa, Cadbury Lunch Bar, Cadbury Chomp, Cadbury PS Caramilk, and Cadbury Crunchie. From Nestlé, the firm favourites are Kit-Kat, BarOne, and Aero. Tiger Brands sells over 120 million of those yummy pillows of deliciousness, the Beacon Easter marshmallow eggs over the Easter period.
We love our chocolate
We certainly love our chocolate, and it is now believed that this love for chocolate goes as far back as 5300 years ago. In 2018, a team of archaeologists working in Ecuador discovered beautiful pottery vessels, in the ancient village of Santa Ana-La Florida. These pottery vessels reminded Michael Blake of the vessels used by the Maya to make cacao drinks. Three types of analyses were done to confirm Blake’s instinct.
DNA analysis of the cooking residue revealed sequences which matched the DNA sequences in modern cocoa trees. The analysis of the shape of the starch grain revealed a shape seen only in cocoa tree seed pods. The presence of markers for theobromine, a compound found in the products of the cocoa tree, was confirmed.
Theobromine (and caffeine, which is also found in chocolate), is classified as an adenosine antagonist. Adenosine plays a signalling role in various functions and pathways in the human body. In the brain adenosine levels play a role in the sleep-waking cycle; in the heart adenosine levels play a role in heart rate activity; and in the kidneys, adenosine levels determine how much blood is filtered; (and therefore the quantity of urine produced); in the blood adenosine levels play a role in blood vessel dilation; in the lungs adenosine levels play a role in the constriction of airways
Theobromine and caffeine are very similar in terms of their chemical structure, with caffeine having an extra methyl group compared to theobromine. When caffeine is broken down in the body, a percentage of the caffeine is converted to theobromine. Two other molecules are also formed, and these are theophylline and paraxanthine.
A little bit of Science
Theobromine is used as a vasodilator, a diuretic, and a heart stimulant. It has a smaller effect than caffeine on the central nervous system. In 2004, scientists from Imperial College discovered that theobromine was more effective than codeine in treating persistent coughs. In 2018, another study concluded that test subjects receiving a fixed portion of dark chocolate, administered as a snack had lower levels of inflammatory markers than the control group who did not get to snack on any dark chocolate. Both sets of subjects had to follow therapeutic lifestyle guideline changes.
Dark, milk, or white?
It must be mentioned that theobromine levels are significantly different in dark, and milk chocolate, with dark chocolate containing higher levels of theobromine. This is often attributed to the greater quantity of cocoa liquor used in the manufacture of dark chocolate. White chocolate contains the least amount of theobromine. The concentration of theobromine in chocolate also differs according to the places from which the cocoa beans are sourced to make the chocolate.
Processes in chocolate making
Aside from the conching technique spoken about in the first part of this piece, there are a number of other processes involved in chocolate production. These include the fermentation, drying, and the roasting of the cocoa bean. During the fermentation phase, which occurs at the cocoa plantations, the naturally occurring sugars are broken down by yeasts and bacteria. It is during this stage that the chocolate aroma begins to develop. The beans are then dried to achieve a moisture content of between 6 – 8% to prevent the growth of mould during transportation and storage. The roasting phase which occurs at temperatures between 120 and 140 degrees Celsius is when more of the magic occurs. One of the reactions that occurs is the Maillard reaction. You’ll know some of the familiar results of the Maillard reaction if you enjoy the smell of freshly toasted bread, or if you enjoy the scent of a well-roasted chicken.
For the Masterchef fans
If you’re a fan of Masterchef, you’ll remember that the contestants have to temper chocolate in most of their dessert making challenges. Tempering is the process which affords a stable final product having the desired sheen and snap of a good chocolate. And there’s still more chemistry involved in this process. Tempering involves the formation of consistently sized crystals and subsequently the development of a stable crystalline structure.
The next time you eat a piece (or a slab?) of your favourite chocolate, perhaps you could give some thought to all of the chemistry that has gone into its production, and all of the chemistry that is about to happen within you.
This piece has appeared before in The Witness.