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What Are Fat Bloom and Sugar Bloom, and Do They Make Chocolate Unsafe?

What Are Fat Bloom and Sugar Bloom, and Do They Make Chocolate Unsafe?

Ever opened up a chocolate bar and noticed a whitish dusting or streaking across the surface?  Don’t be so hasty to toss it in the trash! These light-colored blemishes found on chocolate are pretty common, and they’re usually the result of sugar or fat bloom.

Neither one of these blooms is harmful, but it’s still nice to know what’s going on when your food changes appearance. Here’s what sugar and fat bloom are all about—plus how to prevent them from happening in the first place.

Sugar Bloom

Sugar bloom is characterized by a white, dusty, grainy coating that appears on the surface of chocolate. To understand why this occurs, you first need to recall two things:

  • Chocolate consists of ground cocoa beans as well as sugar—and that means sugar crystals are distributed throughout the chocolate.
  • Sugar crystals are attracted to moisture—and when they come into contact with it, they dissolve.

You probably see where this is going...sugar bloom happens when chocolate comes into contact with moisture. This could happen for several reasons: Perhaps someone stored the chocolate in a humid environment. Or maybe they stored it in the fridge and then removed it to sit at room temperature; this can result in condensation (aka moisture) forming on the chocolate.

No matter how moisture comes in contact with chocolate, the end result is the same: The moisture dissolves the sugar on the chocolate’s surface. Then, as the, the moisture evaporates, the sugar re-solidifies into small crystals leaving behind a layer of dried sugar on the chocolate. These crystals create the “dusty” appearance that characterizes sugar bloom. This “dust” will disappear if you re-wet the chocolate, because the sugar crystals will dissolve again. (Which is not to say you should re-wet the chocolate! But it is a way to test whether the change in appearance is due to sugar bloom.)

Luckily, preventing sugar bloom is pretty easy: Simply store chocolate in a low-humidity space with stable temperatures and do everything in your power to avoid letting the chocolate come in contact with liquids.

Fat Bloom

Fat bloom can be identified by grayish streaks that appear on the surface and potentially throughout the chocolate. Most commonly, this results when chocolate is exposed to warm temperatures, which causes the cocoa butter (aka fat) in the chocolate to soften. When the fat melts, it separates from the other ingredients in the chocolate and rises to the surface, where it then re-solidifies and creates a grayish “bloom”. Due to the separation of the cocoa fat from other ingredients, the chocolate can lose its temper and shine.  

Given this, it’s probably not surprising that the most effective way to prevent fat bloom is to store chocolate in a cool (read: not hot) place with stable temperatures.

In some cases, the chocolate may already have fat bloom on it when you buy it. This is could happen at a number of different points in a chocolate bar’s journey to you; either at the source, in transit while being shipped, in the storeroom at your local grocery store, or maybe from being left on your counter during the summer when your air-conditioner is broken.. There’s nothing you can do to turn back the clock on fat bloom, but you can take comfort in knowing that your new chocolate bar’s grayish appearance probably isn’t the result of a major issue, it just may be a little less flavorful than you’d like.

No matter whether your chocolate is suffering from sugar or fat bloom, the bloom is likely to change the texture of the chocolate. While this might be off-putting to some, the good news is that it’s still safe to eat and cook with chocolate that has been affected by either type of bloom.