Same chocolate. Different Temperature.

The same piece of chocolate at different temperatures. The one on the left was taken when this piece of chocolate was cold, the one on the right was taken when the piece was room temperature. The only difference is an hour of resting.

No, the chocolate piece on the left is not untempered or “bloomed”. In fact, this is the exact same piece of chocolate. The only difference? Temperature.

This is actually a piece of dark chocolate gianduja (cacao, hazelnuts, sugar). Adding nuts or other fats to the chocolate mixture when refining the chocolate will alter the fat crystallization properties of the chocolate.

The image on the left was taken when the chocolate was removed from the refrigerator (and no, it is not sugar bloom either). The chocolate on the right is the exact same piece of chocolate after about 1 hour of acclimating and warming up to room temperature on its own.

Normally, plain dark chocolate (cocoa beans and sugar) will remain dark whether chilled in the fridge or left at room temperature. But not this piece of dark chocolate gianduja. Why is that?

Fat Eutectics. Basically, cocoa butter fats mixed with the hazelnut fats changes the way the chocolate bar sets, its melting point, and other characteristics. This chocolate is softer than a regular dark chocolate. The same thing happens with milk chocolate (where the milk fat mixes with the cocoa butter, and changes the overall properties).

We may not see it, but the way the fat molecules sit can orient themselves according to a few things, and one of those things is temperature. As well, you may hold a solid piece of chocolate and think it’s a complete solid. In some cases, this isn’t so. There are still some cocoa butter molecules that are “free” and not set in the structure of the chocolate. These “free” fat molecules can actually move via capillary action.

The hazelnut fat/oil does not set at room temperature like chocolate does, and so there are many more of these “free” fat crystals within the chocolate. Changing the temperature of the chocolate can force some of these to move around.

We may think of our solid chocolate bars as stable, but in reality they are very unstable, and this little experiment helps us to see this. For those who are chocolatiers and have had issues of weird markings or what appear to be bloom on your chocolate bars removed from the fridge after setting, keep in mind that if you let them rest a few hours or overnight, those markings may disappear!

Chocolate is a simple product, but very complex. Part of the fun, and frustration, of working with it.