Chocolate · 2.2

From bean to bar: fermentation, roasting, conching

Six stages, and only two of them create flavour. The rest can preserve what exists or lose it.

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Six stages take a pod on a tree to a bar in your hand, and only two of them create flavour. The rest can preserve what exists or lose it, and cannot add anything back.

Fermentation, where the flavour is made

Beans are scooped from the pod surrounded by a white pulp and left in heaps or wooden boxes for several days. Yeasts consume the sugars in the pulp, then bacteria take over, the temperature climbs, and the germ inside the bean is killed.

During that process the compounds that will later become chocolate flavour are formed inside the bean. Almost everything that distinguishes one origin from another is decided here, by farmers, in the field, without instruments.

A badly fermented bean cannot be rescued. No amount of careful roasting or conching downstream puts back what was never made, which is why makers who care talk about their fermentation and why they pay more for beans from producers who do it well.

Drying

Usually in the sun over about a week, turning the beans by hand. Moisture comes down to a level that will survive shipping and the sharp acids produced in fermentation evaporate off.

Dried too fast and the acidity stays in; too slowly and mould arrives. It is the least glamorous stage and it accounts for a large share of defects.

Roasting, where flavour is developed

Heat drives reactions between the amino acids and sugars created during fermentation, and those reactions produce the aromas we recognise as chocolate. This is the second stage that makes something.

Roast lightly and the origin character survives; roast hard and everything converges on a general roasted flavour, which is what mass chocolate does deliberately, because consistency is the product.

Cracking, winnowing and grinding

The roasted bean is cracked and the light shell blown away, leaving the nibs. Grinding them releases the fat, and at that point the solid turns into a thick liquid: cocoa mass, which is roughly half fat and half solids, and is unsweetened chocolate.

Sugar, and milk powder if it is a milk chocolate, are added here, and the whole is ground finer until the particles are too small for the tongue to feel individually. Coarse chocolate feels gritty for that reason and nothing else.

Conching

Hours or days of continuous warm agitation. It does three things: it coats every particle in fat so the texture becomes smooth, it drives off remaining volatile acids left over from fermentation, and it allows further slow flavour development.

The process was introduced in 1879 by a Swiss maker and is the reason chocolate stopped being gritty and sharp. Under-conched chocolate tastes acidic and feels rough; over-conched chocolate is smooth and dull, because the volatiles that left included ones worth keeping.

Tempering

Cocoa butter can set into several different crystal forms and only one of them is any good: it gives the snap, the gloss, and a melting point just below body temperature.

Getting it requires taking the chocolate through a specific sequence of temperatures while stirring. Done properly, the bar breaks with a sound and melts on the tongue. Done badly, it is soft, dull and slightly crumbly.

What to ask a maker

How the beans were fermented, and how dark the roast is. Both are questions makers enjoy, both are answered in a sentence, and between them they predict most of what the bar will taste like before you have eaten any.

What large-scale production does differently

Blends beans from many origins to hold a flavour constant across years, roasts harder so that variation between batches disappears into the roast, and conches for a long time to remove anything sharp.

Each of those is a reasonable decision for a product that must taste identical in every shop, and each removes exactly what a small maker is trying to keep. Neither is wrong; they are answers to different questions.

Why a bar goes pale

Two different things produce the same appearance. Fat bloom is cocoa butter that has migrated to the surface and recrystallised, usually after the bar got warm; sugar bloom is sugar dissolved by condensation and left behind when the moisture evaporated, usually after the bar came out of a fridge.

Both are harmless and both change the texture. Neither indicates that the chocolate has spoiled, and the storage entry in this part covers how to avoid them.

What the labels claim

Bean to bar means the maker started from beans rather than from finished chocolate. Single origin means the beans came from one country or region. Single estate means one farm. None of the three is a claim about quality and all three are claims about traceability.

They matter because they tell you whom to ask about the fermentation, which is the stage that decided how the bar tastes.

Why small makers exist at all

Because the decisions that produce a distinctive bar are the same decisions that produce variation between batches, and variation is exactly what a large manufacturer is organised to eliminate.

A festival table is one of the few places you can taste the results side by side and decide for yourself whether the variation is worth it.

Also in this part

• 1.1

  Why a dry red and a sweet chocolate fight

  The wine must be at least as sweet as the food. Everything else in this entry is a qualification of that sentence.

  Read it →
• 1.2

  Tannin and fat: what happens in the mouth

  Astringency is not a flavour. You are noticing the absence of lubrication that was there a moment ago.

  Read it →

For further context, see FAO guide to processing cocoa beans.