What's That Weird White Stuff That Grows on Old Chocolate?

Finding old candy can be a blessing and a curse. On the one hand, free candy. On the other, it's usually grown some weird white stuff in its five years under your bed, and you're not sure what the hell that is. Mold? Parasites? A ghost?? It's actually a "bloom" and it's totally safe to eat. We're going to tell you why.

As the educators at HowStuffWorks explain, there are two types of bloom: sugar and fat. Sugar bloom is usually dry and spotted, while fat bloom is streaky and greasier (because, you know, it's fat). Sugar bloom happens when the surface of the chocolate gets wet. The moisture dissolves the sugar, and, when the chocolate dries, sugar crystals remain on top. Usually, it's a storage problem -- as in, you're keeping the chocolate in a warm space, so its surface starts sweating.

Fat blooming happens when the fat in the chocolate's cocoa butter migrates to the surface. Hoarding your Snickers stash in a warm pantry can also kickstart this process, but rapidly changing temperatures are another trigger.


Since the white stuff is just sugar or fat, it's not going to hurt you if you eat it.But the chocolate might taste a little off, since blooming affects texture. Some people really notice a difference, others don't. It probably depends on how comfortable you already are with the idea of eating Kit Kats from Halloween '07.

In a study published this year in the ACS Applied Materials & Interfaces journal, a team of scientists examined blooming under X-ray to better understand the process. The researchers concluded that yes, you really should store your chocolate in cooler temperatures, but also that confectioners should produce chocolate with fewer pores, so the fats would move more sluggishly. While the latter point is on the Wonkas of the world, you can do your part to prevent sugar/fat blooming by sticking your candy in the freezer. It'll probably taste better anyway. You're welcome, and class dismissed.

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Kristin Hunt is a staff writer for Thrillist, and never lets candy last more than a few months. Follow her at @kristin_hunt.