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🍫 Chocolate: from bitter seed to bar

A raw cacao seed tastes awful. Follow the microbes, heat and crystals that turn it into chocolate.

6
lessons
~30 min
to learn
🔬 Science
subject
Adults
level
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What you’ll learn

  1. The pod on the trunkDescribe the cacao tree, its pods and seeds, and why the crop is confined to a narrow tropical belt.Cacao pods grow straight from the trunk, hold thirty to fifty bitter seeds in wet pulp, and are harvested by hand in a band roughly twenty degrees either side of the equator.
  2. Fermentation makes the flavourExplain how the microbial succession in a fermentation box kills the seed and creates the flavour precursors chocolate depends on.Yeasts, lactic acid bacteria and acetic acid bacteria work in the pulp; the heat and acid they generate kill the embryo and release enzymes that free the amino acids and sugars roasting will need.
  3. Roasting, grinding and the smell of chocolateConnect the Maillard reaction to fermentation precursors, and follow the bean through winnowing, grinding and refining.Roasting builds hundreds of aroma compounds from fermentation's precursors; nibs are then ground to a fat-rich liquor and refined below the particle size the tongue can feel.
  4. Cocoa butter is a strange fatExplain cocoa butter's polymorphism and why tempering produces gloss, snap and a melting point just under body temperature.Cocoa butter can set in six crystal forms; tempering is a temperature routine that leaves only stable Form V, which melts near 34 °C and gives a bar its shine and snap.
  5. The machines that invented the barTrace the nineteenth-century inventions that turned a drink into a moulded bar, and read a chocolate label critically.The cocoa press, the first moulded bar, milk chocolate and the conche arrived within fifty years; the percentage on a wrapper is a sugar gauge, not a quality one.
  6. From the upper Amazon to your pocketPlace cacao's use and cultivation in time and space, from Amazonian origins to today's West African concentration and its risks.Cacao was used in the upper Amazon around 5,300 years ago, became currency and a foamed drink in Mesoamerica, and is now grown mostly by West African smallholders under real disease pressure.

Questions this course answers

A cocoa bean arrives at the factory badly under-fermented. What can the roaster do about it?

Roasting builds aroma out of free amino acids and reducing sugars that fermentation released inside the bean. If fermentation was cut short, those precursors are missing and there is nothing for the Maillard reaction to work on.

Put the journey of a cacao seed in order, from tree to bar

Everything before drying happens on the farm, and everything after it happens in a factory - often on another continent. The split is why farm practice matters so much and is so hard for a manufacturer to control.

At roughly what temperature does the crystal form we want in tempered chocolate - Form V - melt?

Form V melts at about 34 °C, just under human body temperature of around 37 °C. That is why a properly tempered bar is solid in your hand and liquid a few seconds after it reaches your tongue.

Match each microbe or process to what it contributes in the fermentation box

The microbes never get inside the seed. They work in the surrounding pulp, and what reaches the bean is heat, alcohol and acid - which kill the embryo and let the seed's own enzymes loose on its stored proteins.

Why does chocolate need tempering at all, when other confections simply set?

Cocoa butter is polymorphic - at least six crystal forms with different melting points. Tempering is a temperature routine that destroys the unwanted forms and leaves stable Form V seeds to template the whole bar.

Complete the sentence about the wrapper

Since almost all of the remaining 30% is sugar, the percentage is really telling you how sweet the bar is. It says nothing about origin, fermentation, roast or conching time.

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