Bliss and darkness

Chocolate. Take a minute to think about enjoying a delicious piece of your favourite chocolate, won’t you? That moment when you bite and it snaps into your mouth with a light crunch, and the rich warm flavour of it starts to diffuse throughout your mouth. As you inhale, the flavours and aromas flood your olfactory senses. Your brain releases a burst of pleasure chemicals in reaction to the sensations your mouth is enjoying. With each bite, it melts more and more, luxuriously coating your tongue, filling each and every tastebud with luxurious sensations and deep, complex flavours.

Chocolate is a fascinating thing. As with all of the greatest of life’s pleasures, it’s complex and intricate. And the science of chocolate is a blend of different facets of chemistry and biology no less complex than the flavours it possesses. Similarly intricate is the history chocolate shares with society. Human beings have been enjoying chocolate for at least 4000 years. Coming from the plant genus theobroma (literally meaning “food of the gods”), it was originally used by the Aztecs and Mayans in the ancient Americas. The traditional use was to grind the cocoa beans and brew them into a hot drink, together with chilli and other spices. This drink was known in the Nahuatl language as xocolātl, which is possibly where the word “chocolate” originated. So beloved were the cocoa beans to the people of South America that some cultures even traded them as a form of currency. Since then, chocolate has found its way to the very heart of human culture, and is enjoyed almost everywhere humanity places its feet, including being taken into space by astronauts.

Take a step back, now. A step back to what’s happening in your body as you bite into a nice luxurious bar of chocolate. Laced with the alkaloid drugs, caffeine, theobromine and phenethylamine, the chocolate stimulates your nervous system, latching onto the dopamine and adenosine receptors in your brain. Your pulse rate increases and you start to sweat lightly, as a wave of dopamine washes over your cerebrum. Your muscles contract, your skin starts to tingle, and your senses sharpen. You salivate as the chocolate melts slowly in your mouth. As it continues to do so, your brain continues to release pleasure chemicals. Serotonin and endorphins flood your senses, relaxing you in spite of the stimulant effects your body is experiencing. Sharpened senses, elevated heart rate, deeper breathing, tensed muscles and dreamy relaxation. All at the same time. No wonder chocolate is so blissful.

Chemically, chocolate is rather interesting too. A dispersion of cocoa solids and milk solids, encased in a soft cocoa butter matrix. Cocoa butter is the fatty oil found in cocoa beans, and it’s the magical ingredient that allows chocolate to melt at approximately 1 degree below human body temperature, allowing that delectable feeling of the chocolate melting as you bite into it. A good chocolatier will work carefully to treat their chocolate to give it that perfect taste and texture. After being fermented and dried, the cocoa nibs are treated with an alkali (often potassium carbonate) prior to roasting them, to improve the flavour (a process known as “ducting”). The amount of alkali needs to be just enough so that it catalyses the Maillard reaction and enriches the flavour, but not too much or the triglycerides in the cocoa butter will start to saponify, and that flavour will be ruined. The cocoa should be roasted carefully so as not to burn it, but enough to enrich the colour as the roasting produces tannins. Those tannins then oxidise, darkening the cocoa still further. These roasted nibs are then ground and liquefied into what’s known as chocolate liquor — the purest most unadulterated form of chocolate!

The chocolate liquor is then blended, with cocoa butter, to whatever extend is desired. The darkest chocolate is virtually pure chocolate liquor with enough cocoa butter to set it. Milk chocolate typically contains vanilla as well as milk, to enrich the flavour, and white chocolate omits the cocoa solids altogether, containing purely cocoa butter and milk. This blend is emulsified and “conched” — the liquid is swirled around metal beads which grind all the solid particles finely. The finer they are, the smoother the chocolate, and the silkier it feels in your mouth as you savour it. The highest quality chocolate is conched this way for at least 72 hours to ensure it’s as perfectly smooth as can be.

But with the final stage, there’s more left than just pouring it into a mould and allowing it to set. Just as a master blacksmith has to make sure steel is the perfect consistency as it cools, a master chocolatier ensures that chocolate is just right. Both work in the same way. Chocolate is tempered, just as metal is. Cocoa butter is actually capable of existing in 6 different crystalline forms, and in order to make sure it crystallises just right, care must be taken to heat treat it properly. Only one of those crystal forms gives the best chocolate. Get the temperature wrong and it will melt too easily, or taste gritty. At just the right temperature, the chocolate needs to be worked, to create the right kind of seed crystals — phase V crystals. Only once there are enough phase V seed crystals in the mixture, can it be left to cool and solidify into the perfect chocolate. Smooth, glossy, and crisp. Blissful.

Images from parsectraveller and gnuf on flickr.

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
This entry was posted in chemistry, Imported from Livejournal, molecular gastronomy. Bookmark the permalink.

4 Responses to Bliss and darkness

  1. Wally says:

    Thanks for reminding me about my daily serving of chocolate. I knew I was missing something in my breakfast today. By the way, great blog. Keep it up.

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