The words “chocolate” and “disappointment” don’t often go together.
But you may have been disappointed if you’ve ever unwrapped the shiny foil of an Easter egg to discover chalky white chocolate inside. What is this white stuff? Is it mold? Bacteria ? Is it bad for you? Can we still eat it?!
The answer is yes, you can! This is called “blooming” and is caused by the fats or sugar in the chocolate. To understand why it forms and how to prevent its formation, we need to consider the chemistry of chocolate.
The good thing
Easter egg chocolate is made with a relatively small number of ingredients: cocoa beans, sugar, milk solids, flavorings and emulsifiers to keep it all mixed together.
The fermentation and roasting of cocoa beans trigger many chemical reactions that develop delicious flavors. In the same way that peanut butter can be made from peanuts, roasted cocoa beans are ground into a paste known as cocoa liquor.
The liquor is mixed with the other ingredients and ground with heating (known as conching) to form liquid chocolate.
The fluidity of cocoa liquor comes from the fats released during the grinding of the beans. These fat molecules are known as triglycerides and look like the letter Y with three long zigzag arms connected at a central junction. The triglyceride arms can vary, but they tend to be a mixture of saturated and unsaturated fatty acids.
When the melted chocolate cools, these triglyceride fats assemble into highly ordered structures that are molecular-scale crystals. Depending on how the temperature is controlled, fats can take on one of six different crystal structures. These different crystal forms are called polymorphs.
Control your temper
The most sought-after crystalline form gives chocolate a smooth, shiny appearance, clean snap and melt-in-your-mouth texture. Achieving this requires careful temperature control from liquid to solid through a process called tempering.
Poorly controlled cooling of melted chocolate results in other forms of crystals, which tend to have a less pleasant appearance and mouthfeel – often chalky or gritty. These less desirable forms may convert during storage. And as the underlying crystal structure of fats changes, some of the triglycerides separate.
These separated fats accumulate on the surface as colorless crystals, giving the chocolate a bloom of white fat. This is especially noticeable if the chocolate is improperly stored and goes through melting and re-solidification.
Ingredients can also affect fat bloom. Inexpensive chocolate tends to use less cocoa butter and more milk solids, which introduce more saturated fat. Saturated fats are also common in nuts and can migrate from the nut to the surface of the chocolate. Thus, a chocolate-covered hazelnut is more likely to exhibit oily bloom than a nut-free version.
Sugar or fat crystals?
Sugar bloom is less common than fat bloom, although they can look very similar. It occurs when sugar crystals separate from chocolate, especially under humid storage conditions.
You can tell the difference with a simple test. The sugar flower will dissolve in a little water, while the fat flower will repel water and melt if you touch it for a while. Unfortunately, chocolate bloom can only be reversed if you completely melt the chocolate and recrystallize it at the correct temperature.
The easiest way to prevent your Easter eggs from blooming is to choose a brand with a high cocoa butter content, transport and store your eggs at low temperature and humidity, and make sure to eat them before they are best before date – assuming they last that. long!
Read more: Want to shop for guilt-free Easter chocolate? Choose from our list of “good eggs” that perform best for the environment and child labor