Why Chocolate Turns White (and Whether You Can Still Eat It)

You open a bag of chocolate and it has gone dull and greyish, sometimes with a chalky feel. That is bloom. It is not mould, the chocolate has not gone off, and it is safe to eat — but it looks poor and the texture suffers.

The two kinds of bloom

Fat bloom is the common one. Cocoa butter is a fat that can set in several different crystal structures. Properly tempered chocolate is set in the stable form, which is what gives it gloss and snap. Warm it above about 25°C and the fat begins to melt and migrate to the surface; when it cools it recrystallises in a coarser, unstable form, and that is the pale film. It repeats every time the chocolate warms and cools.

Sugar bloom is different and less common. It happens when chocolate gets damp — condensation on the surface dissolves some of the sugar, then the water evaporates and leaves sugar crystals behind. Fat bloom feels greasy if you rub it; sugar bloom feels gritty.

Why it is worse between May and September

British houses are the problem, not the chocolate. A cupboard that sits at 16°C in February can reach 26°C in July, and a delivery van in summer is warmer still. Every warm-then-cool cycle makes bloom more likely, which is why the same product can arrive perfect in November and dull in August.

How to store it

• Cool, dark, dry, and above all steady. Consistency matters more than cold. 15–18°C is ideal.
• Not the fridge. This is the mistake people make. A fridge is humid, and taking chocolate in and out causes condensation on the surface — which is exactly how you get sugar bloom. If you have no choice in a heatwave, seal it airtight first and let it come back to room temperature still sealed.
• Away from anything strongly scented. Cocoa butter absorbs odours readily. Chocolate stored next to coffee or spices will taste of them.

Can you still eat bloomed chocolate?

Yes. It is a cosmetic and textural change, not a safety one. It will taste slightly less smooth and more waxy. Bloomed chocolate is perfectly good for baking, hot chocolate or anything where it gets melted — melting resets the crystal structure entirely.

What we do about it

We pack to order rather than holding pre-bagged stock in a warm warehouse, and in high summer we suggest smaller bag sizes on chocolate lines so it is eaten before it has time to cycle through several warm days. If chocolate arrives bloomed after a hot spell, tell us — that is a legitimate complaint even though the product is safe.

Two different kinds, and how to tell them apart

“Bloom” covers two separate faults with different causes. Telling them apart takes a
second and tells you what happened to the chocolate.

Fat bloom looks like a soft grey haze or pale streaks, feels slightly greasy,
and melts away under your thumb. Cocoa butter has migrated to the surface and
recrystallised in a coarser form. Cause: it got warm, then cooled. A car, a windowsill, a warm
delivery van.

Sugar bloom looks like a fine gritty dust, feels rough and dry, and
does not melt when you touch it — it dissolves if you wet it. Moisture has
condensed on the surface, dissolved some sugar, then evaporated and left the sugar behind. Cause:
condensation. Almost always the fridge.

Is it still safe?

Yes. Both are physical changes rather than spoilage — nothing has gone off and nothing has
grown. Chocolate at this sugar and fat content is a hostile environment for microbes, which is why
it keeps so well in the first place.

What does change is texture. Bloomed chocolate is grainier and melts less cleanly, and fat bloom
in particular flattens the flavour because the cocoa butter is no longer holding the aromatics in
the right structure. It is fine to eat and it is disappointing to eat, which is a different
complaint.

It is also perfectly good for cooking. Melting it re-tempers the fat, and once it has set again
in a properly tempered form the bloom is gone. See
how to melt marshmallows for the same
principle applied to the other awkward ingredient in a s’more.

Why tempering is the whole game

Cocoa butter can set into six different crystal forms. Only one of them — form V —
gives chocolate its snap, its shine and its clean melt at body temperature. Getting it there is
what tempering is: taking the chocolate through a specific temperature curve so the right crystals
form and the wrong ones do not.

Bloom is that structure falling apart. Once the chocolate has been warm enough for the form V
crystals to melt, it re-sets into the coarser forms, and there is no way back short of melting and
re-tempering it.

Storing it properly

• Not the fridge. This is the one people get wrong. The fridge causes sugar
  bloom, and taking chocolate in and out causes condensation every time.
• 15–18°C, dry, dark, sealed. A cupboard away from the oven. Chocolate
  also picks up smells readily, so keep it away from anything strong.
• In summer, if you must chill it, seal it in an airtight box first and let it
  come back to room temperature before opening it, so moisture condenses on the box rather
  than the chocolate.

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