Chocolate Bloom Explained

Yesterday a friend of mine sent me a panicked text about chocolate.

She was gathering ingredients to make a chocolate cake and she noticed that her chocolate had turned “white.” Our conversation went something like this:

Kim: Carolyn! Is my chocolate ok?! Is that mold?!
Me: It’s fine, you can use it. It’s called “chocolate bloom”
Kim: Am I going to die if I eat it? I’m making a bday cake – the livelihood of others is on the line
Me: No one is going to die. It’ll taste the same, just melt it like usual
Kim: Ok, thanks!
Me: I think you need a glass of wine…
Kim: Probably more than one.

Kim had sent me a photo of her chocolate. It resembled this:


You’ve probably been through this before. Walk into the pantry to grab the bag of chocolate chips or blocks of baking chocolate. You open the package and the chocolate looks old and dusty, like a box in grandma’s attic.

“Attic” chocolate!

That’s called “blooming” and there is no reason to panic!


Let’s talk science, shall we?

First let’s address the ingredients in chocolate. Most baking chocolates are made of cocoa (in the form of powder, liquor, or a combination), cocoa butter, and some elements of sugar and soy lecithin (prevents the cocoa and the cocoa butter from separating). The latter ingredients are what distinguish unsweetened, bittersweet, and semi-sweet chocolate varieties.

Chocolate, in its form as baking bars, chocolate chips, etc., is a shelf-stable product…so long as you treat it with care.

In a basic scientific explanation, things stay the same unless an external agent is introduced. This can be called stability, constancy, or equilibrium.

That chocolate bar wants to stay the way it is. Unfortunately, our kitchens are not stable environments. The weather changes outside (temperature swings, rain, snow, dry heat, humidity), you open and close windows, and the pantry gets shuffled around. If you’re in my house, Dan finds his way into the bag of chocolate chips when you’re not looking, forgets to seal the bag, and the next day he blames it all on the dog.

When chocolate is exposed to the “elements” for a period of time, the chemistry of the chocolate changes. Typically this occurs in one of two forms…


What is “Bloom”?

There are two main causes of bloom: Fats and Sugars

Fat Bloom:

Fat bloom occurs when the cocoa butter separates itself from the cocoa solids. This is usually due to drastic temperature change. Ever left a chocolate bar in your car and then tried to “freeze” it back to a solid state? It probably suffered from fat bloom and looked like the surface of Mars was covered in a blanket of chocolate…mmmmm…

If Mars is made of chocolate, put me on the next shuttle!

Fat bloom will make the chocolate more brittle. It also probably won’t taste as delicious if you simply eat it. However, it works “normally” in any recipe that requires you to melt or temper the chocolate. All the ingredients are still there, they have just have to be put back together. You need to melt it all back to chocolate harmony. Check out a great tutorial on tempering chocolate (without ruining it) here.


Sugar Bloom:

Sugar bloom is the result of water or moisture coming into contact with the chocolate. This is what happened to poor Kim.

When moisture comes in contact with chocolate, the sugar separates (in a similar manner to the cocoa butter above), causing the sugar to crystallize. From a glance sugar bloom looks like chalk or dust. But if you zoom in, it will remind you of tiny Champagne bubbles.


The dusty white stuff on the outside is crystallized sugar that has risen to the top/outside of the chocolate. A quick fix to this is to grate off the bloom (I prefer a thin Microplane but any grater will do). You don’t have to go crazy because it is a very thin layer. Your chocolate will look good as new!

Similar to chocolate that has suffered by fat bloom, sugar bloomed chocolate can still be used in recipes that require melting or tempering. You can throw still use chocolate chips that have experienced sugar bloom, but the chips will still look chalky in the final product.


Preventing Chocolate Bloom

It’s all about storage. To prevent fat or sugar bloom, it is best to keep chocolate in an air-tight container, in a cool, dark place, and away from windows, heat sources, or other things that affect temperature.

I recommend a small, glass Snapware tub to keep air and moisture out.


Can chocolate expire?

Absolutely. Typically chocolate bars last between 4-6 months stored (properly) in the pantry, and may last a few extra months if stored in the fridge or freezer.

When in doubt, throw it out. Expired chocolate does not have a distinct visual change but the flavor is often bitter. It will not be remedied by melting or tempering.

In my house chocolate never expires. It gets eaten way before that could ever happen, but word on the street is that not everyone has the same self-control issues that we do. Guilty as charged.

There you have it! Chocolate science!

And if you’re wondering, Kim’s cake turned out great, the birthday party was a blast, and nobody died.

Bake on!



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