Tempering Chocolate

It’s now time to take half of batch 9, temper it, and pour it into bars. The chocolate has aged about a week now, and I’m going to leave half of the 2.2 lb batch to age longer for comparison purposes. I melted and tempered the other half tonight, hopefully yielding glossy bars with a nice snap and good mouthfeel.

What is tempering, and why do we do it to chocolate? Chocolate is cocoa solids trapped in a matrix of solid and liquid fat. That solid, crystallized fat is what gives chocolate its texture. Solid fat forms into crystals, and one form of crystallized cocoa butter has the near magical property of melting at 94F, just below body temperature, vital for the experience of chocolate. It’s also remarkably stable, and will let the chocolate keep for a long time. Unfortunately, cocoa butter will crystallize (mainly) into four different crystal configurations. We want the chocolate in the one stable configuration out of those four, so we have to do some magic. Each of the configurations has a different temperature that it will form at, and melt at. We need to manipulate the chocolate to get it into the right temperature to form the stable crystals, provide it with seed crystals, and keep the bad crystals from forming.

So, here’s the block of chocolate that I put up a week ago.

bloomed chocolate

Ghastly! This is bad case of bloomed chocolate. It looks like some kind of alien mold has taken up residence on the chocolate. In reality, the chocolate has cooled to a bunch of random crystallizations, most of which are unstable. This lack of stability has caused liquid cocoa butter to leach out of the chocolate and migrate the surface, where it crystallizes in those odd circular patterns. Can it be saved?

Click “more” below to see photos of the chocolate rescue.

chunks of untempered chocolate

When this chocolate is broken, it cleaves very roughly, and appears to have random chunks of solids in it. Tempering will fix all of this.

110F chocolate

We first bring the chocolate to a temperature above the melting point of all the crystal forms, to essentially push the reset button and liquify the chocolate. Working in a double boiler, we get it to 100-120F. To do a really great job, we’d hold the chocolate here overnight to insure that no residual crystals are present. We’re working a little more quickly, so I’ve just held it here for about an hour.

mushing chocolate

Next, we cool the chocolate to 92F by changing the double boiler insert over to a pan of cool water, and extract about 20% of the chocolate onto a marble slab. We then repeatedly smear the chocolate into a thin layer on the slab, and regather it. This agitates the chocolate and creates some appropriate seed crystals. The chocolate will have the right amount of crystallization when it resembles cake frosting (thus the name “mush” method.)

reincorporating seeds

We then reincorporate the seeded mass into the main mass of the chocolate, which we maintain at 85-90F by changing back over to a pan of warm (96F) water. If all goes well, this should be tempered. My temperature control is imperfect here, which will cause a problem we’ll see later.

shards of tempered chocolate

Here are some shavings that set up on the marble slab. Note that they break with clean edges, and there’s a nice shiny surface on the larger pieces. Check out the difference between how this chocolate breaks and the untempered chocolate in the second photo. I think we have success!

bars of tempered chocolate

Here are some poured bars. (Astute observers will note the streaks in the chocolate. These are “hot streaks”, and are due to imperfect tempering. These streaks may bloom and cause problems later. With practice, I’m hoping to minimize those.) With any luck, they will unmold cleanly, since properly tempered chocolate will shrink as it cools, make it easy to remove from the mold. Hand tempering is pretty tricky, since you need to actively manipulate the temperature of the chocolate in a fairly tight range, and the transition from untempered to tempered is basically invisible. Skilled chocolatiers can see proper temper, and can tell the degree of temper by putting a small amount of chocolate on their lips.

Since this process is so (in Terry Richardson’s words) “artsy”, most commercial chocolate is tempered by machine, which yields a very uniform, quality result. Doing this by hand definitely gives you a feel for what’s going on, which is vital when the machine is not doing what you expect!

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