Ask the Alchemist #335 - Shell Tempering

Level: Novice

Read Time: 4 minutes

When I make bon bons using polycarbonate molds, I temper the chocolate, make the shells (i.e., fill mold and pour out), fill with ganache and seal bottoms with more tempered chocolate.  The release for the mold just fine and have a nice shiny finish. When I bite into the bon bon, the tempered shell breaks with the the normal snap.  But, when I get gourmet bon bons from other makers who use the same molds, the shells are much softer and do not crack/snap when I bite into them. They blend more smoothly with the filling. They hold their shape like my tempered shells and do not melt on my fingers with I pick them up.  What can I do to make my shells like this?

Yep, that is a problem.  I’ve been there myself, most notably when I have made truffles and decided to roll them in tempered chocolate.  They crack and shatter when you bite into them.  The issue is two fold.  When chocolate tempers it both shrinks (which is why they crack as they harden) and like many crystals, becomes more brittle.  You hear all about tempered chocolate having snap. That snap is the brittleness and the source of your problem.

We have identified the source.  Let’s address it.  

In short, you need to reduce the brittleness and to do that, you reduce the temper.  Yep, you can have more or less temper.  How? For a really deep dive for the geeks go read Degree of Temper.

What I talk about in Degree of Temper is adjusting your temper by controlling the temperature to make the conditions for Type V crystal development less favorable.  I’m not a huge fan of this method as it probably varies chocolate to chocolate and takes some trial and error.  Getting it wrong means bloomed shells.  It may be that it will be your only option if you have a recipe you like and don’t want to change it for some reason, be it purity (Duck Purity BTW), allergen restrictions or something else.  

Changing the recipe slightly for your shells is my preferred method.  You are looking to add an ingredient that will disrupt the crystal structure.  The main options are:

• whole fat milk powder

• cream powder

• milk fat (clarified butter)

• coconut oil

I suspect the difference in your shells and the ones you bought is probably a bit of milk or at least milk fat in the shells.  It is possible they use some other oil or modifier but there is no way to know.

You are probably going to need to do a little bit of experimentation if you are going with one of the moo juice fats.  I outline how to go about that in Ask the Alchemist #330.  TLDR #FAFO.  Somewhere around 5-10% gets you in the ballpark.

If you can’t do the cow thing, or don’t want change the flavor of the shells, then coconut oil is the way to go.  I’ve said many times that you have to be careful using coconut oil for the exact property we are going to exploit here.  I suggest adding 2% coconut oil to your recipe.  Temper the chocolate (using Silk is the easiest way) and make a few shells and see what you think.   Add more coconut oil if they are still too hard, less if they are too soft.

As far as your shell not bonding to the truffle filling I suspect it is the lack of some milk fat in the shell again.  Assuming you are using cream in the truffle filing, a little milk fat in the shell will then give the shell and filling some affinity for each other.  The old chemistry adage like attracts like applies here.

I hope that helps.

Good luck and keep those questions coming.  You can submit them HERE.  Now is a great time to submit as we ramp up for a busy holiday season and I’ll have less time to ponder the the airspeed of a chocolate laden swallow.