Ask the Alchemist #132


Super interesting and inspiring! I wonder if the TAG content changes during conching? If so, has anyone measured the before conching, during conching, after “too much” conching?

I can’t imagine how it would. I want to take a moment and do a review as there is hardly a week that goes by that I don’t have the desire to clarify to someone the different between conching and refining.

Refining, in the context of chocolate making, is the physical process of reducing the particle sizes in your chocolate. In the basic sense, it is done by rubbing two hard surfaces together in the presence of the chocolate, crushing the particles in between. This can be done with pairs of steel rollers (roller mill), steel balls and a steel container (ball mill), steel plates slapping and sliding together (refiner) or by granite wheels rolling on a slab of granite (Melanger). In all cases you have two hard surfaces rubbing against another on (there roller mill is an exception where sheer forces between the two rollers break things apart) ‘wearing’ the chocolate particles down.

Conching, in contrast, is honestly much less understood. The two schools of thought (at least) on what is going on. In either case chocolate is stirred and agitated. But the key here is that nothing in the chocolate is getting smaller. There is no refining going on. Either way, it is thought that in one form or another chemical reactions are happening. In the classic sense, the chocolate is oxidizing, volatiles are being driven off and other ‘simple’ reactions are occurring. The second school of thought is that some ilk of molecular enrobing is happening, each particle of sugar and such are being ‘coated’ in cocoa butter, hence the smooth mouth feel. I personally find that a bit mystical and full of hand waving. And kind of ignores that chocolate is already smooth from a particle size point of view, due to the refiner, when it goes into conch. Whatever is happening then is pretty clearly does not involve the shape of the particles since they are already beyond detection. I think that descriptive ‘smoothness’ is nothing more than a sensory illusion created by the chocolate not firing off ‘sharp’ reactions in your mouth because all those ‘sharp’ molecules (acids and such) have been turned into something softer (fruity esters and Maillard reaction by products).

With those out of the way, you are asking if the TAG (triaclyglyceride or long chains of the cocoa butter molecule) can lengthen or shorten (the only changes that would change the TAG content). The short answer is no. I’m going to just blithely toss my chemist credentials down and say I’ve found no chemical reactions that would or could do this. If you can find one, please let me know and I’ll be thrilled to change my mind. The main reason is that you need what are considered active groups in a chemical for something to occur mano a mono, i.e. without a specialize enzyme (again, none of which I know of). And the only active groups in a TAG are at that three carbon chain hold the three chains together. The other end (or center) is basically inert and for lack of a better descriptor, are immune to chemical attack.

The list of reactions that could happen on the business end of the molecules are pretty short…..to the point that the only one that I can find that is applicable in a food setting would be saponification. Or the making of soap. And it has three major problems. It requires water, a strong alkaline solution and it would make the chocolate taste of soap.

And I can hear it now (I’ve actually had this conversation) - How about if we alkalize the chocolate, then there is base, and so a tiny reaction can occur and one fatty acid chain can swap places with another? That’s a pretty picture, but as I learned in first year Organic chemistry, chemistry doesn’t work that way. For ANY reaction of this type to proceed it has to be overwhelming feasible and pushed. And pushing in this case is LOTS of water, and LOTS of base (think lye). To put it in perspective, think of pushing a large truck uphill. One toddler (the weak base) can’t push a truck even on a flat surface. Even one 8 year old can’t get it rolling. A single adult might be able to get it rolling if flat, but in order for the reaction to occur, you need a LOT of force (base) and it is going to take many strong adults to push a truck up hill and get it going fast. That’s what it takes. A little does nothing.

So, since conching is now officially off the table, let’s talk about refining or melanging (the combination of the two). ‘Can’t the refiner grind off a piece of that long carbon chain, turning it into a different one?’ And of course, the answer is basically no. The scale is all wrong. Molecules don’t crush. Although not literal, you have to cut them. Can you ‘cut’ a carrot (long thin thing) with a wrecking ball? Or even better, how about a piece of string? Silly isn’t it? It just doesn’t work. It will move out of the way, and twist and turn and nothing will happen.

And even that scale isn’t quite right.

Picture if you will one of the Spectra Melanger wheels the size of the earth. What you need to cut is a piece of 1/2” diameter rope a little over a foot long…and the rope is floating in a pond (of cocoa butter). That’s the scale we are talking about. It’s hard to even picture it happening isn’t it? And basically, if you can’t picture it (i.e. come up with a realistic descriptive) it just isn’t going to happen in real life. The rope in water will just flow out of the way when the two earths come rolling past one another…and that is assuming you can even trap that piece of rope. Most likely, it will just sit protecting in the craters of uneven surface since even your smooth rollers are ‘pitted’ horridly on the molecular level.

As for adding on to the ‘rope’ of the individual TAG how would you stick two pieces of rope together…using the earth. There just isn’t a way. The ends are inert and won’t stick to anything else.

Long story short, I see no reason or even way the TAG composition could change with either refining or conching. Any changes you see during either of these processes are going to be from some other mechanism.

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