How Is Chocolate Made?

Cacao trees grow in a band roughly twenty degrees either side of the equator. The pods grow straight out of the trunk and branches, and each holds thirty to fifty seeds surrounded by a white pulp.

The pods are cut down by hand and opened, since machinery damages the seeds. At this point the seeds are pale purple and taste nothing like chocolate. The pulp is sweet and pleasant, and it turns out to be essential to what comes next.

The seeds and pulp are heaped together and left to ferment for several days. Wild yeasts consume the sugars in the pulp, then bacteria take over, and the heap heats up substantially.

This kills the seed, which stops it germinating, and triggers chemical changes inside that create the precursors of chocolate flavour. Without fermentation there is no chocolate, only bitterness. The beans are then dried in the sun to bring the moisture down and halt the process.

Roasting develops flavour through the Maillard reaction, the same browning chemistry behind seared meat and coffee. Temperature and time here shape the final character considerably.

The shells are then removed, leaving nibs, which are ground. Because cacao is over half fat by weight, grinding produces a thick liquid rather than a powder. That liquid is cocoa mass, and it can be pressed to separate cocoa butter from cocoa solids.

Different chocolates are different ratios of the same handful of ingredients:

• •Dark chocolate is cocoa mass, cocoa butter and sugar
• •Milk chocolate adds milk powder, reducing the cocoa proportion
• •White chocolate uses cocoa butter with no cocoa solids at all
• •Lecithin is often added in tiny amounts to help everything flow smoothly

Conching is prolonged mixing and warming, sometimes for many hours, which smooths texture and drives off harsh volatile acids. It is a large part of why some chocolate feels silky and cheap chocolate feels gritty.

Tempering is the final and most technical step. Cocoa butter can crystallise in six different forms, and only one gives a glossy surface, a clean snap and a melt just below body temperature. Tempering guides the fat into that form through careful heating and cooling. Untempered chocolate sets dull, soft and streaky, which is exactly what happens when a bar melts in a car and resets.

The economics of chocolate are uncomfortable. Most cocoa is grown by smallholder farmers in West Africa, particularly Ivory Coast and Ghana, and the farmgate share of a finished bar's retail price is small.

Low prices have been linked to persistent problems including child labour and deforestation, documented repeatedly by researchers and journalists. Certification schemes exist and have had mixed results in independent evaluations. There is no simple consumer fix, but the gap between the price of a bar and the income of the person who grew it is a real and well documented feature of the industry.

For thousands of years cacao was drunk rather than eaten. Peoples of Mesoamerica, including the Maya and later the Aztecs, ground roasted beans into a bitter, frothy drink, often flavoured with chilli or vanilla, and the Aztecs even used cacao beans as a form of currency. After Spanish contact in the sixteenth century, the drink travelled to Europe, where sugar was added and it became fashionable among the wealthy. It was still a gritty, fatty beverage, because nobody yet had a good way to separate cocoa butter from the solids.

That changed in 1828, when the Dutch chemist Coenraad van Houten patented a press that squeezed out much of the butter, leaving a cake that could be ground into cocoa powder. Having spare cocoa butter made the modern bar possible. In 1847 the Bristol firm Fry's mixed cocoa butter back into cocoa and sugar to make a paste that could be moulded and set. Swiss makers developed milk chocolate in the 1870s, and Rodolphe Lindt's conching machine in 1879 produced the smooth texture people now expect.

You can temper chocolate in your own kitchen with nothing more than a thermometer, using the seed method. Gently melt about two thirds of your dark chocolate to around 45 to 50 degrees Celsius, which destroys all the existing fat crystals. Then stir in the remaining third, finely chopped, and keep stirring as the mixture cools. Shop-bought bars are already tempered, so those unmelted pieces contain the right kind of cocoa butter crystal, and they act as seeds that encourage the rest of the fat to set in the same stable form. For dark chocolate, aim for a working temperature of about 31 to 32 degrees.

Milk and white chocolate need slightly lower working temperatures, because milk fat interferes with the cocoa butter crystals, and makers often suggest around 29 to 30 degrees for milk and a degree or so less for white. Test before you pour by smearing a little on a knife or a strip of baking parchment. Properly tempered chocolate sets glossy and firm within a few minutes at a cool room temperature. If it stays soft or dries streaky, warm and stir it again gently. Overheating well past the working temperature melts the stable crystals and means starting again, which is why gentle heat matters more than speed.

If you have found a bar with dull grey or white streaks, it has probably bloomed rather than gone mouldy. Fat bloom happens when chocolate is stored somewhere warm or its temperature swings up and down. Some cocoa butter melts, moves to the surface and recrystallises in a less orderly form, scattering light so the surface looks pale and dusty. Sugar bloom has a different cause. When cold chocolate comes out of the fridge, moisture condenses on it, dissolves a little sugar and leaves a rough, whitish crust as it dries. Both types spoil the look and texture, but the chocolate is still safe to eat.

Chocolate also contains theobromine, a bitter compound closely related to caffeine, which gives cacao part of its mild stimulating effect. People break theobromine down fairly quickly, but dogs process it far more slowly, so it builds up in their bodies and can cause vomiting, a racing heart, tremors and, in serious cases, death. The danger depends on the amount eaten and the size of the dog. Dark chocolate and cocoa powder contain much more theobromine than milk chocolate, while white chocolate contains very little, because the compound sits in the cocoa solids rather than the cocoa butter. Cats are sensitive too, though they rarely seek out sweet foods.

Chocolate is made by fermenting and drying cacao seeds, roasting and grinding them into a fatty liquid, then blending, conching and tempering it, with fermentation creating the flavour and tempering creating the snap and shine.