What's this white stuff on my chocolate?

You're about to get your mid-afternoon chocolate buzz on, when you see it -- a white, powdery or streaky substance on the surface of your afternoon delight. What is this stuff? Did the store sell you nasty chocolate or did your supersaver sweetie hit the clearance rack when picking up a treat for you? And, most importantly, is it OK to eat?

Chocolate bloom is a scourge of the chocolate maker (those who process the cacao bean into chocolate) and chocolatiers (those who use the finished product to make candy or confectionaries) alike. It's actually pretty complex, starting with the fact that there are two different kinds: sugar bloom and fat bloom. Sugar bloom is usually a dry, spotted coating, while fat bloom tends to be streaky and greasier. It can be hard to tell by looking, as the difference is really due to chemical changes.

If you've never encountered chocolate bloom, you might be freaked out when you first see it. Rest assured, bloomed chocolate is perfectly safe to eat -- it hasn't gone bad and it's not old at all. It might be less than appetizing though; bloom can not only change the chocolate's appearance but also its texture. Some people claim they can't tell a difference, but others won't touch the stuff.

Sadly, there's no way to fix bloomed chocolate unless you want to melt it down. While we can't help you decide whether to eat your chocolate or not, we can help you keep it from happening in the future -- maybe.

A Blooming Problem

When chocolate's exposed to too much moisture, sugar bloom can happen. That's because sugar is a hygroscopic substance -- in other words, its crystals suck up moisture and retain it. If sugar gets wet enough, it might even dissolve a bit in the surface water. When the chocolate dries, the larger sugar crystals are left behind on the surface as a white powder.

Sometimes, the problem happens long before the product hits the shelves. If the chocolate wasn't properly refined (which reduces the size of its sugar crystals) during the chocolate-making process, the larger crystals could absorb moisture more readily. If your chocolate has a delicious filling of some kind, the culprit could be too much liquid introduced when it was formed. Sugar bloom is typically a storage issue, though; if you keep chocolate in a damp room, condensation can form on its surface. This can also happen at the grocery store or in your own fridge, so stash your chocolate in a cool, dry place if you want to avoid sugar bloom.

OK, so we know when sugar's the cause of bloom, but what about fat? Improper storage can also cause fat bloom. If it's just warm enough, the cocoa butter in the chocolate will separate a bit and settle on the surface of the chocolate, forming greasy streaks. Fluctuating temperatures can also be to blame.

However, mistakes during the chocolate-making process are most likely to cause fat bloom. Chocolate must be tempered -- a process of repeatedly raising and lowering the chocolate's temperature to create uniform, stable crystals of cocoa butter. If tempering isn't done just right, the differently sized crystals can transform over time, and voila -- you've got bloom.

Here are some other potential fat bloom-causing scenarios:

The chocolate maker doesn't allow the sweet treat to cool properly before packaging it.
There's another type of fat injected into the chocolate that melts at a different temperature than the cocoa butter does (this is sometimes done in less expensive chocolate because cocoa butter is pricey).
Warm chocolate is paired with a cold filling (in general, chocolates with a filling that contains fat are more likely to fall prey to fat bloom).

Blame the chocolate maker, blame the store or blame yourself. But if you don't want to eat bloomed chocolate, you can probably find somebody who will!

Chocolate Bloom FAQ

What does it mean when chocolate blooms?

Chocolate blooming occurs when the chocolate is exposed to warm temperatures. The warm chocolate softens the cocoa butter that's present in the chocolate, separating it from the other ingredients. This rises to the surface where it solidifies and turns into chocolate bloom.

Is it safe to eat bloomed chocolate?

Chocolate that has bloomed is safe to eat since it is a non-perishable food. However, the white marks could give it an unappetizing texture and appearance.

Is chocolate okay to eat if it turns white?

When chocolate blooms, the cocoa butter rises to the surface and re-solidifies. This creates white markings on the chocolate. While it does have an unpleasant appearance, it is okay to eat chocolate that has white marks.

How long does it take chocolate to bloom?

It usually takes up to 4 weeks for chocolate to bloom. It has been found that chocolate blooming tends to occur quicker if the chocolate is exposed to very high temperatures.

What are the types of bloomed chocolate?

There are quite a few types of bloomed chocolate. Sugar blooms are white spots that appear on the surface of the chocolate. Fat blooms are streaked lines that appear on the surface of the chocolate that are white or gray.

Lots More Information

Sources

Beckett, S.T. "The Science of Chocolate." Royal Society of Chemistry. 2000.
Longchampt, Pierre and Richard W. Hartel. "Fat bloom in chocolate and compound coatings." European Journal of Lipid Science and Technology. April 2004. (Jan. 14, 2012) http://onlinelibrary.wiley.com/doi/10.1002/ejlt.200400938/pdf
Nemours. "Candy Experiments: Chocolate Bloom." KidsHealth. 2012. (Jan. 11, 2012) http://kidshealth.org/kid/closet/experiments/candy_chocolate.html
Partos, Lindsey. "Fat bloom findings bring savings for chocolate makers." Food Navigator. Sept. 22, 2004. (Jan. 15, 2012) http://www.foodnavigator.com/Science-Nutrition/Fat-bloom-findings-bring-savings-for-chocolate-makers
Smith, Kevin W. et al. "Effect of Antibloom Fat Migration from a Nut Oil Filling on the Polymorphic Transformation of Cocoa Butter." Journal of Agricultural and Food Chemistry. Feb. 7, 2008. (Jan. 15, 2012) http://dx.doi.org/10.1021/jf072151s
Struempler, Barbara. "Blooming Chocolate Won't Hurt You." Alabama A&M and Auburn University Cooperative Extension System. 2012. (Jan. 11, 2012) http://www.aces.edu/dept/extcomm/newspaper/chocolate2.html