What you see: A light, whitish/grayish/beigeish powdery coating on chocolate
What it is: “Bloom,” the result of fat or sugar exiting the “chocolate matrix” and then crystallizing on the surface
Eat or toss? Eat! The chocolate may have lost some of its oomph, so if the taste is grainy or otherwise off, melt it into hot chocolate and you’ll never know the difference
So why does it look like a ghost has haunted your chocolate?
The culprit is probably something called bloom, which comes about when temperature or humidity fluctuations mess with fat or sugar, causing them to flee their positions in a perfectly blended chocolate bar and then awkwardly recrystallize on the surface.
Enter the chocolate matrix
Between the two types of bloom, fat bloom is more common, occurring when temperatures above 85 degrees Fahrenheit cause the white cocoa butter fat in chocolate to liquify and then migrate to the surface.
Unfortunately, it's tough to outsmart the Bloom Ghost by hiding your stash in the fridge. That’s because the other chocolate-disfiguring bloom, sugar bloom, is prompted by humidity, and fridges are humid places. Moisture dissolves the sugar and then, once conditions are drier, the water vapor evaporates; its calling card is sugar crystals on the surface. You can try wrapping your chocolately treasure tightly to keep out moisture, but it takes a major effort to keep that humidity out.
And, any time you move chocolate from a cold place (a heavily air-conditioned office?) to a warm place (your car?) condensation could occur and bloom could follow.
Storage temperature is key
So, store your chocolate in a cool, dark place that isn’t the fridge. Something in the 60 degree range is great. And if you do freeze your chocolate, just keep in mind that once you take it out of the freezer, you’ll want to eat it quickly because the condensation threat is real.
But storage alone isn’t the only way to impact bloom.
Battle of the bloom
Different ingredients can put your chocolate more at risk for bloom. Chocolate with fillings can be more susceptible because of the moisture or types of fats they might contain. Santa Barbara Chocolate notes that, over time, rum soaked raisins would prompt sugar bloom because of moisture. Some oils, including peanut and coconut oils, aren't compatible with cocoa butter and increase the odds of bloom.
Also likely prompting bloom during chocolate making are dirty spots on the trays used to shape the confections; such spots trigger crystallization. Another culprit: a more airy chocolate which provides corridors for fat to travel to the surface.
Melissa Tisoncik, writing for Blommer Chocolate, notes that some manufacturers use “strategic layering” to prevent bloom; a layer of caramel separating nuts, which may contain incompatible oils, and chocolate, can keep the bloom at bay. (And, yes! Someone with Blommer Chocolate is writing about bloom!)
Delicious techniques like creating a denser chocolate and mixing with milk fats can help prevent bloom. But have you ever had chocolate with a waxy or gummy texture? Chances are the manufacturer replaced some of the cocoa butter with vegetable fats or oils and/or excess sugar. Bloom avoided, but icky texture achieved.
No matter what, even the fanciest, most expertly prepared chocolate will get bloomy after about two years. Milk chocolate and chocolates with fillings—particularly nuts, which can go rancid—are looking at shorter timelines. (But really, who lets chocolate reach that age?)
While bloom-y chocolate may look like it’s been spooked, it is still edible. Close your eyes and you may not notice a difference. If you do, then follow The Kitchn’s lead and use it in cookies, or stir it into some warm milk and cream for hot chocolate, which I can confirm works beautifully.
Special thanks to Jules, a girl scout in Washington, DC who suggested a post on this topic!
Chocolate Fat Bloom. Melissa Tisoncik. Blommer Chocolate Company. The Manufacturing Confectioner. April 2013. P. 65 - 68.
X-Rays Reveal How Chocolate Turns White. Emily DeMarco. Science. May 7, 2015
Why does chocolate turn white? Allison Russo. The Kitchn. Feb. 18, 2017.
Why Your Chocolate Turns White (Yes, You Can Still Eat It). Jackie Donnelly. Chococurb.
Why is my chocolate turning white? Chocolatier Jason Vishnefske. Oct. 23, 2016. Santa Barbara Chocolates.
Why does chocolate turn gray sometimes? Is it still safe to eat? How Stuff Works.
X-Rays reveal why old chocolate turns white. Marissa Fessenden. May 9, 2015. Smithsonian
Where'd the chocolate go? You know, the bar that had some bloom on it? It ghosted...