Why is my chocolate turning white? (And no, it's not mould)

You open a chocolate bar that's been sitting in the pantry for a few weeks, and there it is: the surface is covered in a whitish, almost powdery film. The instinct kicks in: straight to the trash. Big mistake.

That film has a name, a specific mechanism, and above all, it's completely harmless. It's what's called chocolate bloom, and here's everything you need to know before sacrificing your bar.

First things first: it's perfectly safe to eat

Bloomed chocolate isn't mouldy. It hasn't gone bad, and it poses no health risk. The taste, in the vast majority of cases, stays intact or nearly so. Only the texture changes a little: grainier, less silky, a little dull to look at.

In other words, your chocolate might be less pretty, but it's still very good. It's up to you what to do with it.

Two types of bloom, two very different stories

There are two forms of bloom, caused by two distinct processes. People often confuse them, but they have nothing to do with each other.

Fat bloom

The most common one. It happens when part of the cocoa butter migrates to the surface of the chocolate and forms fine fat crystals there. Visually, you get a uniform white film or patches, sometimes with a slightly greasy feel.

The causes are almost always tied to temperature:

• Chocolate stored somewhere too warm
• Large temperature swings (repeated warm-cold cycles)
• Chocolate that was poorly tempered to begin with (especially in homemade mouldings)

Cocoa butter has a low melting point. When the temperature climbs above 25-26°C, it starts to soften, moves through the chocolate, and then re-crystallizes elsewhere as it cools. Hence the film on the surface.

Sugar bloom

Less frequent, but more dramatic. It happens when moisture comes into contact with the chocolate. The sugar at the surface dissolves in that moisture, then, as the water evaporates, it re-crystallizes into a grainy, almost sandy layer.

The usual culprit: the fridge. When you pull chocolate out of the fridge, condensation forms on its surface almost immediately. Result: sugar bloom, guaranteed.

This form of bloom is more textured, less uniform, and gives the chocolate a characteristic "frosted" look.

How to prevent bloom

Three simple rules cover 90% of cases.

Store it in the right place. Ideally between 15 and 20°C, away from light, in a dry spot. A cool cupboard in a temperature-stable room is perfect.

Skip the fridge. Except in extreme heatwaves, chocolate has no business in the refrigerator. The moisture and temperature swings when you take it out are its number-one enemies.

Wrap it well. Once opened, chocolate keeps best tightly wrapped in its original paper or in an airtight container. It picks up smells easily (cheese, onions, spices): keep it well away from all of that.

What to do with bloomed chocolate

Absolutely no throwing it out. Here are three options, in order of ease:

Melt it down. Melting redistributes the cocoa butter and completely erases the bloom. The chocolate goes back to smooth and glossy, ready for any recipe. Our guide How to melt chocolate walks through every method.

Use it for baking. Brownies, fondants, cakes, ganaches, mousses: cooking or emulsifying erases every trace of bloom. This is the best use for chocolate that's had a little wear and tear.

Re-temper it. For those who do their own moulding or coating, you can melt it and temper it cleanly. The chocolate regains its original shine and snap.

Good chocolate blooms more slowly

Not all chocolates are equal when it comes to bloom. A well-made couverture chocolate, properly tempered from the start and rich in cocoa butter, is more stable and holds up better to small temperature swings.

Our 55% dark chocolate drops, our 34% milk chocolate drops, and our dark chocolate bar are couverture chocolates built for the kitchen. Stored well, they last a long time without blooming.

Going further

• Our guide How to melt chocolate, to start from clean ground
• Our guide How to make a perfect ganache, to turn your chocolate into dessert
• Juliette's cookbooks: Mon Année Chocolat and Les Brownies de Juliette, both in the Recipe Books by Juliette collection

All our cooking chocolates are available online (free shipping on orders of $99 and up, across Canada), in our restaurants, and at the boutique of our Chocolate Workshop in Greenfield Park, on Montreal's South Shore.

A useful reminder: next time you open a bloomed bar, before you dramatically toss it, remember the solution is probably in your saucepan or your mixing bowl.