Why can't we cool the chocolate directly to get form V crystal seeds?


That is a very good question.  And when I received it, I didn't know if it was true or not.  Many 'rules' we live by turn out to be myths and we do what we do because that is how it's always been done.  Or sometimes it is simply the most expedient way to do them.  Maybe, I thought, it was possible to form Type V crystals direct.  Assuming it was, why would it not be done that way.  The only reasonable explanation I could come up with was the rate of reaction, or basically how fast it takes the crystal structure to form.

With that hypothesis in mind, I set up a few tests to test the theory. 

It was really simply really.  I melted a few pounds of dark chocolate, set my tempering machine to 88 F, and just let it go. I took pairs of samples out at various intervals.  30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 24 hours, 48 hours, 72 hours and 96 hours.  One sample I let set up at room temperature (about 65 F), the other went into the refrigerator for fast chilling (just to see if there was an effect).  I also repeated this at 86 F, 90 F, and 92 F.  The results?  100% bloomed chocolate.  To me that is a very definitive result that Type V crystals do not spontaneously form.  If they did, they would be seed crystals and allow the lattice formation of Type V and the chocolate would not bloom.

This result was not really surprising.  Otherwise it would be an accepted practice.  As I thought this over, it reminded me of some of my basic chemistry lectures on transition state theory.......and I've now spent WAY too long trying to come up with neat yet comprehensible pictures or diagrams showing how I understand what is most likely going on....and I failed.  It's not that it's really hard, but I can see the deer in the headlights look know if I try to put it up.  So I won't bother.  What you and I  will have to settle for is a less accurate but hopefully more comprehensible description.  And my favorite...analogy.

Basically, it Type V is not stable.  It's sort of a definition thing.  Things like to be stable.  Generally that means given the option, they will go to the lowest energy state.  Since chocolate left to it's own devices does not spontaneous temper (form Type V) but instead blooms, the bloomed state must be the stable one.  Since it is the stable one, and since tempered chocolate can bloom without intervention, tempered chocolate is the opposite, or unstable.

I can't really (easily and simply for non-chemists) explain why that leads to this next part, but trust me, it does.  Because Type V is unstable, it has more energy than Type IV.  That higher energy is why you can't just make Type V from nothing. It is too big of a jump per se.  Tempered chocolate is like being on a roof.  Untempered is being on the ground.  You just can't make that leap.  But Type IV is a step half way there.  If you can get onto the step, you can then get onto the roof.  And that is it in a nutshell.  You have to make Type IV  first. After that, it can turn INTO Type V.

If you want a slightly better visual, think tinker toys (google it you youngesters).  Think of making something long that twists and turns and lays 'just so'.  You can't just build it.  Every time you try it just falls apart, or spins around and just won't stay in place.  But if you build it on the ground, flat, it's nice and stable.  Type IV.  Then, with the floor helping to support it, you can rotate just the way you need, and what was impossible in one step, is suddenly possible.  Type V.

That's it.  For the more technically hungry, if you have not caught on by now, we are talking about transition state theory, with Type IV being the lower energy transition state from untempered chocolate that allows formation of the higher state Type V.



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