Life's Little Mysteries

Why does chocolate turn white (and is it safe to eat)?

These old praline chocolates are blooming with white markings. (Image credit: Trygve Finkelsen via Getty Images)

Imagine you are about to finally enjoy the chocolate you got from trick-or-treating on Halloween, from your darling on Valentine's Day or during an egg hunt on Easter, only to unexpectedly find it covered with pale spots. Are they bad for you? Can you still eat the chocolate?

Rest assured: The chocolate is indeed safe to eat. What you see is the result of a natural reaction known as "chocolate blooming." To learn why chocolate blooms — and what you might want to do about blooming — it helps to understand how chocolate is made.

Chocolate is made with cacao beans that are fermented and roasted to help trigger chemical reactions that create delicious flavors, Nathan Kilah, a research chemist at the University of Tasmania in Australia, wrote in The Conversation

"The average cocoa bean contains about 50% cocoa butter and 50% cocoa fiber," chocolatier Jason Vishnefske, owner and co-founder of chocolate factory Santa Barbara Chocolate in California, told Live Science. Cocoa butter is the fatty part of the cocoa bean, while cocoa fiber is the dark part of chocolate.

What is the difference between cocoa and cacao? The tree, pod and bean are usually referred to as "cacao," while the word "cocoa" is reserved for the bean after it has been fermented and roasted, according to Lake Champlain Chocolates, a chocolate factory in Burlington, Vermont. 

Related: Who invented chocolate?

Cocoa fiber helps give regular chocolate its color and much of its taste, while cocoa butter is responsible for chocolate's richness, Santa Barbara Chocolate explained. Cocoa butter happens to melt at about human body temperature, leading to chocolate's "wonderful melting sensation," Vishnefske said.

After cacao beans are roasted, the shells are separated from the nibs — the "meat" — of the beans, Lake Champlain Chocolates said. The nibs are then ground up into a paste known as cocoa mass, cocoa liquor or chocolate liquor. Despite its name, chocolate liquor does not contain alcohol, according to Santa Barbara Chocolate.

Dark chocolate is made with cocoa mass. Milk chocolate is also made with milk. White chocolate is made with cocoa butter and milk, leaving out cocoa fiber, per Santa Barbara Chocolate.

This chocolate is blooming with white splotches. (Image credit: nbehmans via Getty Images)

Chocolate blooming happens when molecules within the candy start moving. "There are two basic types of bloom — sugar bloom and fat bloom," Vishnefske said.

Fat bloom happens when cocoa butter migrates to the surface of the chocolate "due to heat, light exposure or improper handling," Vishnefske said. Fat bloom appears as a white sheen or blotchy white spots.

Sugar bloom "is brought on by storing chocolate in a moist environment, or by removing cold chocolate from a refrigerator and exposing it to the moist air, just as a soda bottle coming out of the refrigerator will collect moisture," Vishnefske said. "Sugar bloom is noticeable as a rough, gritty surface and finely speckled appearance."

When chocolatiers make chocolate, a process of heating and cooling liquid chocolate — known as tempering — "gives chocolate its strength, wonderful sheen and smooth melt," Vishnefske said. "Bloomed chocolate has lost its crystalline structure, thereby disrupting the melt sensation and causing an imbalance of flavor profiles. In bloom, the sugar, the fat and the cocoa fiber have become disharmonious, brittle and unattractive."

Large chocolate companies suppress fat bloom by reducing cocoa butter levels or by adding bloom inhibitors, such as vegetable fats or oils, Santa Barbara Chocolate said. Adding sugar or cocoa powder — cocoa mass that has been dried, powdered and had most of its cocoa butter removed — can also minimize bloom during manufacturing, the company noted. However, these additions influence the flavor of the chocolate, and sometimes make it seem waxy or gummy. 

Chocolate blooming is harmless, although bloomed chocolate may have a chalky or gritty mouthfeel, Kilah noted.

"The good news is that it is pretty easy to revive bloomed chocolate," Vishnefske said. "Proper tempering will realign the crystalline structure and restore the shine, snap and smooth melt."

Instead of throwing away bloomed chocolate, "you can revive it with quick microwave tempering, or use it in your baked goods that don't require the tempered crystalline structure of solid chocolate," Vishnefske said. In addition, "fondue is fabulous and easy. Chocolate-dipped strawberries are quite possibly America's favorite fondue dipping fruit."

Charles Q. Choi
Live Science Contributor
Charles Q. Choi is a contributing writer for Live Science and He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.