During the course of this thread, one of the people I talked to offline was Scott Rao. He emailed me a comment which I thought was relevant; with his permission, here it is:

AndyS wrote:The question still remains whether a wood-fired Probat-style roaster might flavor the beans with wood smoke. It is fact that wood smoke would intimately contact the roasting beans. However: the beans are more-or-less continuously outgassing H2O, CO2, CO, and various volatiles. This would limit the opportunity for smoke flavors to work their way in....

Scott Rao wrote:i've had a similar thought about the beans outgassing and perhaps resisting absorbing smoke. and perhaps that is happening. BUT, anytime i've worked on a machine with compromised airflow, or else on a machine with the damper set to vent the smoke more slowly than the smoke is created, the difference in the cup is huge. smokey, muddled, gross (IMO; some like that stuff). so, the beans do absorb the smoke around them. i can't quantify it, but it's enough for a person with a modest palate to notice (i've had numerous people send me smokey-but-not-dark samples and every time the culprit was poor exhausting of gases and was easily fixed.

so, i'm guessing the wood roasted stuff tastes like wood smoke to a material degree. i look forward to trying some soon, but everytime i've tried it the beans were so darkly roasted that it was hard to tell what was going on.

Also, Trish Rothgeb (formerly roasting at Taylor Maid and Zoka, now roasting at Wrecking Ball in DC), opined that there might be a certain period in the roast when the smoke had the best chance of penetrating. If I remember correctly, the time she mentioned was after the drying period (IOW, after H2O outgassing) and before the chemical reactions get going vigorously in the runup to 1st crack. I hope I'm getting the gist of her comment correctly.

JonR10 wrote:But what if the main "effect" of wood-fired roasting is from using wood fire as the heat source?

This has been discussed earlier and got mixed in with craftsmanship discussion and such. The following was my attempt at a collective conclusion of the many members posted contributions:

Whale wrote:Certainly, the wood burning roasted beans potentially have a different taste characteristics than gas burning or electric heat roasted beans because of the means of heat application, intensity and control being very different and probably requiring a different roasting process. This, along, with the possibility of contact with smoke aromatics could possibly create a different taste characteristic. Additionally the impact of the wood burning on the bean taste, if any, will certainly vary from one roaster to the next.

But is that wood burning taste characteristic only achievable with wood burning? Maybe not, and thus this would mean that the wood burning roasting process does not create a different taste. It would just create that taste differently.

This is still only speculative because never actually tried by anyone that posted.

another_jim wrote:It should be feasible to throw wood chips in with the beans, just as one does when smoking in an oven. My hesitation is that it might mess up the drum surface; although that would nail down the proof that there is a difference.

I am not sure that this would "nail the proof". There is no doubt (in my mind) that physical contact to the actual "burning" wood chips would impart a lot more smoky taste to the coffee beans than combustion gas only but it would certainly be a step forward in "proving" the coffee can be flavoured during roasting.

Nik wrote:I can only compare a recent purchase of Ethiopia Amaro Gayo that was wood roasted by Matt's Coffee in Maine. The first bags came from Klatch which were not wood roasted. I can only say that the flavor of berries was more robust in the wood roasted. However I think there are other factors that would affect it as much as the wood.

I've also had the pleasure of using coffee from Matt's Wood Roasted in Maine (Bird Dog). I can only comment that as espresso, moka pot, french press and immersion/drip it was quite good. I'd not previously seen coffee bloom quite as this did, though my experience with Artisan, fresh-roasted is a bit limited. I will say that it was one of the most memorable coffee experiences I can recall.

yakster wrote:My experience with wood roasted coffee is limited to my own roasts over a campfire using a completely different roasting method then I use at home....

I was planning on trying this at home using different woods (pecan, etc.) and then tasting the coffee after having cleaned up and not being around a fire, but the popcorn popper was left deep inside the tent trailer, so that remains a project for the future... maybe I'll just save some roasts I make camping this summer (if I can).

So, it's camping season again and I roasted six batches of coffee (Sumatra Mandheling GR1 DP, Ethiopia Organic Idido Misty Valley DP GR 1, and Costa Rica "Brasil de Mora" Alajuela) during my first camping trip and took the roasted coffee with me to Plano, TX on a business trip. It was good to have a stash of freshly roasted coffee in the travel kit. I was starting work at 5:00 am and the jet lag really prevented me from doing any sight-seeing or cafe-hunting, I didn't end up drinking anyone else's coffee while I was there.

The roasts were inconsistent due to temperature variations and problems getting the beans to mix resulting in some of the batches having a wide spread of roasts from City to French in the same batch, but I detected no smoke flavor in the cup. I also roasted a batch of almonds, something I regularly do in my Behmor, and the almonds really picked up the smoke, not only in the taste but just smelling the roasted almonds. The smoke flavor was overpowering, on the verge of unpleasant in the almonds, but some of the almonds were also a little over done.

I really enjoy roasting over the campfire as a change of pace and really immersing myself in the experience of open-fire roasting, but I don't have any real desire to do this outside of camping trips anymore.