Chocolate 101 – What’s a Bloom?
More importantly, should you care? The short answer is yes and no. First, let’s take a look at one of the final steps in chocolate making and one that can give chocolatiers the most headaches: tempering. The cocoa butter (fat) in chocolate can exist in six different crystalline states, but only one of these, the beta-1 form, is stable at room temperature. Tempering is achieved by heating the chocolate above the melting point for all the crystalline forms, and then carefully cooling it (this is a simplified explanation). By keeping these fat molecules in a stable crystalline form, you can make chocolate with a beautiful sheen and a nice crisp snap. This is especially important for chocolatiers doing enrobing or coating of filled confections so that the coating can form a nice shell that won’t break apart.
Most, but not all, chocolate makers also go to great lengths to be sure that the cocoa butter and cocoa particles are very tiny and intimately mixed so that the cocoa butter surrounds the cocoa particle. This happens during refining and conching where the sugar is also broken down to a very fine particle size (typically below about 50 microns). All of this just so you can enjoy a smooth, sensual mouth-feel in your favorite chocolate.
Now, when a bloom occurs, some of this hard work is undone. If chocolate gets too warm for too long, the cocoa butter will start to separate out and you will get a whitish, grey-white or tan haze the surface. This is a fat bloom or cocoa butter bloom. Don’t panic! It won’t hurt you and, in all but the most extreme cases, it won’t affect the taste of the chocolate. It just doesn’t look too pretty. If we’re talking about a chocolate bar, go ahead and eat it. OK, were not talking about leaving it in the sun for days – then it may be oxidized and for milk chocolate or filled chocolates start to go bad. Just letting it sit above 75 degrees F for too long or going from cold to warm too fast might produce a minor fat bloom that, in itself, is no big deal. Besides, properly-tempered, high quality chocolate will be more resistant to bloom.
On the other hand, should you store your precious chocolate in a humid place or, more likely, you’ve kept it in the fridge and then move it out unprotected to a warm, humid room, you could produce a sugar bloom. Moisture forms on the cool surface of the chocolate and and “pulls” some sugar out to the surface. The reasons for this are simple: sugar is very soluble in water – it likes to be in water more than in the chocolate. When the water evaporates, nice little sugar crystals are left behind. No big deal. The bar should taste fine except the texture maybe altered since SOME of the sugar is not where is was meant to be. Go ahead and eat it. No worries.
In the end, bloom won’t hurt you. But, it may diminish your tasting experience somewhat since the texture may change to be more grainy or in the extreme, dry and chalky. So, it’s best to handle and store your chocolate carefully to avoid bloom as much as possible. Don’t do what I did and try to induce a bloom by repeated freezing and moving chocolate to a warm (80 degree F) room over a few days. You’ll get the ugly mess in the photo.
Although my self-induced blooming disaster took quite a bit of effort on my part, you’re still probably wondering: “how can I avoid accidentally blooming chocolate?” Stay tuned for a post in the next week or two where you will learn the best ways to handle and store chocolate.