Ingredient

Dark chocolate

Chocolate is a suspension of cocoa solids and sugar in cocoa butter, and cocoa butter is a fat with strong opinions about temperature. Almost every chocolate problem — seizing, blooming, dull set, splitting — is that fat behaving in a way you did not intend.

What the percentage means

The number on a bar is the proportion by weight that comes from the cocoa bean — cocoa solids plus cocoa butter — with the remainder mostly sugar. So 70% dark chocolate is roughly 70% bean-derived and 30% sugar.

It is a useful number and it is not a quality rating. A 70% bar can be made from poor beans; a 55% bar from excellent ones. What the percentage does tell you reliably is how sweet it will be and how it will behave: higher percentages have less sugar, more cocoa butter, set harder and are more prone to splitting in a ganache.

For baking, a recipe assumes a percentage. Substituting 85% where 55% was intended changes the sugar, the fat and the liquid balance all at once.

Melting it without ruining it

1. Chop it evenly. Large lumps melt slowly and the small pieces around them overheat waiting.
2. Use a bowl over barely-simmering water, not touching the water, or a microwave in short bursts at low power.
3. Stir often. Chocolate holds its shape while molten, so it can be scorched underneath and look untouched.
4. Take it off the heat while a few lumps remain and stir them out in the residual warmth. Overheated dark chocolate goes grainy and dull.
5. Keep every drop of water away from it. A wet spoon, a splash from the pan, steam condensing on a cold bowl — any of them will seize it.

Why a little water seizes it and a lot does not

This is the most counter-intuitive thing about chocolate. Melted chocolate is dry particles of sugar and cocoa solid suspended in fat. Add a small amount of water and it wets the sugar, which turns sticky and glues the particles into a stiff, grainy paste. The chocolate seizes.

Add enough liquid — roughly a third of the chocolate's weight or more — and the sugar dissolves properly, the solids disperse into the liquid, and you get a smooth sauce. That is why ganache made with plenty of hot cream works perfectly while a teaspoon of water is a disaster.

So the rescue for seized chocolate is not less liquid but more: whisk in hot cream, milk or even boiling water a spoonful at a time until it comes smooth. You will not get the chocolate back for coating, but you will have a sauce. See seized chocolate.

The other things that go wrong

Bloom — grey streaks or a dusty surface

Either fat bloom, from cocoa butter migrating after warm storage, or sugar bloom, from condensation. Both are cosmetic and harmless. Melt and re-set to remove it.

Dull, soft, fingerprint-marking set

Untempered. Cocoa butter can set in several crystal forms and only one gives snap and shine. Tempering is the process of encouraging that one.

Split ganache

The emulsion has broken, usually from a temperature shock or the wrong chocolate-to-cream ratio. A splash of warm milk and a stick blender usually rescues it.

Grainy melted chocolate

Overheated. Dark chocolate does not like going much above 50°C.

White chocolate misbehaving

It contains no cocoa solids and much more milk solid and sugar, so it burns far more easily. Melt it much more gently.

Common questions