Question: Why Does Chocolate Turn White?
Answer: We get asked why chocolate turns white constantly! It seems that so many people have opened a bar of chocolate or a box of chocolates and found an odd white, filmy appearance on the bar or the bonbons. Is this whitish film on chocolate harmful? Why does it happen?
Contrary to popular belief, a white film on chocolate does not mean that the chocolate is moldy. What it does mean is that the chocolate has suffered something called “bloom”. There are two types of bloom. Sugar bloom occurs when moisture comes in contact with the chocolate. Chocolate that you eat typically contains sugar. Sugar is made up of crystals. In eating chocolate, the sugar crystals are usually fine enough that you cannot see them or feel them on your tongue. Moisture that comes into contact with chocolate will dissolve these sugar crystals on the surface of the chocolate, but as the moisture dries or evaporates, the dissolved sugar re-crystallizes and is precipitated onto the surface of the chocolate, leaving that white, dusty look.
Fat bloom is more complicated and may be caused by a combination of factors. These include improper storage conditions, changes in temperature, or poor tempering (or lack of tempering altogether). When chocolate is afflicted with fat bloom, it may have a powdery white-gray or tan appearance and be soft or crumbly in texture.
Bloom is a constant concern for chocolate-makers and chocolatiers, especially those who ship their products. Once they hand a package for shipping to a courier, that package is “out of their hands” (literally as well as figuratively). They cannot control how the chocolate will be handled or transported or stored as it travels to its recipient. If the box ends up being stored overnight in alternately hot and cold warehouse facilities, it would be a simple matter for the chocolate inside to develop fat bloom. Then, when you or your designated recipient opens the box, the chocolate will have a white or whitish-gray appearance, and the texture may be soft or powdery—not really what you wanted, in either case.
One thing to note: chocolate that has turned white from bloom is not harmful to your health! It probably will not be especially pleasant to eat, but it will not hurt you. And, while it may not be good for eating, chocolate that has bloomed is still perfectly good for many cooking applications and for making hot chocolate. Now that you know the cause of chocolate turning white, you can take care to store it properly, so that bloom will not occur when the chocolate is in your hands.