Level: Apprentice
Reading/watching time: 12 min
I have heard you should stop roasting when cocoa beans start to smell good so you don’t lose all those great flavors.  You don’t really talk about that though. How do you know when to stop a roast?

I’m going to start off with a disclaimer here that these are my opinions based on roasting for over a decade and being actively in the kitchen for over 4 decades.  What that means is I can’t back it up with sources, data and supporting information other than that which I have personal experience.

The Chuncho from Peru I recently had gave off the most amazing aroma of fresh pressed apple juice in its raw state yet it had virtually no apple flavor.  Ivory Coast has no jasmine aroma while roasting but often smells of jasmine in the chocolate.  Honduras has an aged cheese aroma when raw and sometimes a musty aroma while roasting but both are absent in the chocolate.  Roasting coffee has a distinct aroma but it isn’t of coffee.

When you bake bread the lovely aroma fills the house.  Brewing coffee also fills the room with a lovely smell and the same goes with a roasting chicken or roast of beast.

What I want you to notice is that the bread, coffee and meat still taste good after they give off the aromas that give them their own distinct flavors.  You never stop baking a loaf of bread as soon as it starts to smell of bread - to do so would give you an under baked loaf of dough. 

When we smell something it is because there are molecules that have been released from the surface of whatever we are smelling,that have made it to our nose and have fired receptors there.  Those molecules are a gas (they are traveling through the air after all).  But only a very small portion is released from their source.  Many compounds we can smell in the ppt range (parts per trillion) but those same compounds remain in whatever gave them off in the ppb or even ppm (billion and million respectively) range.  It does not release anywhere close to everything it has by orders of magnitude.  Think of a bottle of essential oil or scented candle.  They continue to have aroma basically indefinably because such small amounts are being released at a given time.

The point here is that just because you are smelling something while you are roasting does not mean you are driving it off and out of your chocolate.  Instead it means you have actually developed the aroma compound, a tiny amount has been released from the surface of the bean (very likely where it was just created), it made it to your nose receptors and you smelled it.  Congratulations.

But stopping the roast there would be a shame.  Just like the loaf of bread that is giving off bready aroma while it is still mostly raw dough, your cocoa beans are no different.  The outer layer may be giving off those aroma but the interior hasn’t.  You have to keep roasting to give time for the heat to soak in and the chemical reactions to propagate inward.  This is why I often suggest waiting until you smell chocolate, brownies or the like and then wait an additional 2-3 minutes.   

The other side of this are bad smells.  I rarely talk about the aromas that come off of a roast even though there are a lot of them.  At the end of the day I find they just don’t matter.  They are markers for noting where you are.  During the Roasting Seminar I gave recently we made these notes as benchmarks.

  • 150 - 180 F - Pulls off acids and ketones. unpleasant odors. These do not mean a lot as long as the ramp is under 12 F/min
  • 180 - 195 F - wheat / bread / grain / hay
  • 212 - 220 F - Various nuts / Graham crackers / chocolate
  • > 232 F - Nut smell dissipates. May get a new wave of acidic smells. If these are clean acids (e.g. vinegar) then it is OK. if not a good acid odor; this is not good. Ramp needs to be slowed down
  • 240 - 250 F - Fruit odor takes over (if present in the bean) if you choose you can pull out the beans at this point
  • 260 F - small dip in acidic odor or a change in odor can be detected. Pull out at the dip in the acid odor or if acrid aromas increase radically.

That mention of bad odors is what is important. When I speak of them my intent is that they are obvious and nearly all the time they are related to your heat being too high and you are getting acrid or burning aromas or you are approaching the end of the roast.  What I am not talking about is vinegar since it always happens.  It may be unpleasant but it isn’t bad.  In short trust your senses.  You know what BAD is and it isn’t just ‘I don’t like that’ it is ‘that is wrong’ like when you smell food that has gone bad.  You just know.

But here is the thing, even if you smell something bad, you have not ruined the roast.  The same rules apply.  The outer edge is giving off the aroma but it is a tiny amount of the whole bean and you have time to change things.  When I have explained this to people I invariably get the question about having developed a ‘bad’ flavor deep in the bean and it is only just coming to the surface and the roast is now ruined.  All I can say to that is the theory is ok on the surface but I have never seen it happen.  In all my years I have never had a good bean that didn’t have bad aromas coming off  that ended up tasting bad. My conclusion is that bad flavors don’t just happen without warning. They are created and you can smell them and it is obvious.

That all said, there is one more huge thing I need to point out and it is really, really critical. 

Aroma and taste molecules are related but separate.

That is especially true when the aromas are out of context.  I hinted at this in the third paragraph.  Go back and read it.  I’ll wait……

You are back?  Good.  That fresh pressed apple aroma is just that.  It is an aroma I noted. It could be cause by any number of chemical.  This is just a partial list.

  • trans-2-hexenol
  • butylacetate
  • pentylacetate
  • hexylacetate
  • 4-methoxyallylbenzene
  • methyl-2-methylbutanoate
  • butyl-2-methylbutanoate
  • hexyl-2-methylbutanoate
  • butylhexanoate
  • hexylpropanoate
  • hexylbutanoate
  • hexylhexanoate

But none of these TASTE like apple on their own.  We only associate them with the flavor of apple because we have previous smelled them when we tasted other compounds that give apples their characteristic flavor.  And note I say ‘on their own’?   I once made a strawberry wine.  I fermented it dry. It was horrible.  All the strawberry flavor was gone…or so it seemsed. So much of what we note as given flavor is a combination of so many compounds.  When I fermented the strawberry juice I got rid of the sugar, I changed the acidity and I produced other compounds.  But I didn’t actually destroy the compounds responsible for the strawberry flavor. When I sweetened the wine and adjust the acidity down a bit strawberry flavor came through again.

All this my way of saying just because you smell something (bread, peanuts, violets, whatever) coming off in a roast, don’t think you are driving that flavor away because most likely it is only an aroma compound and was never there as the flavor you were smelling in the first place.  By continuing to roast you are not ‘burning off’ the flavor.  Again, it was not there to start with.  Only the aroma we associate with a flavor was noted and that association breaks down when not in the actual item (like an apple or strawberry) in question.

So how do I know when to end a roast?  Well, NOT by the nice aromas coming off.  Very generally speaking I roast until I just barely notice off aromas in the Finishing phase, plus another minute or so.  Shorter if it is really aggressive but hopefully your Finishing phase ramp is nice a slow (3-4 F/min) so you have time to react before it gets aggressive. And once again, it is totally ok to wait for aggressive aromas as it only the most outer layer giving off those compounds and assuming the rest of the roast has been good (i.e. lacking in bad aromas) those compounds can and will be driven off when you refine since they make up such a small amount of the bean mass AND aroma does not correlate with flavor most of the time.