I want to propose a simple (yet odd) experiment that I'd like to gather input from others who have fully manual controled roasters.

One of the perks of being a hobbyist roaster is it frees us from many constraints. Consistency is mastery of what you've already done, but not always the end point if your aim is just experimentation and learning. I've done many things over the years that go outside the realm of normal, to see what results I end up with.

Of this, by far the most amazing roast I've ever created, was by doing something so odd, and so questionable, that it's almost laughable. I re-roasted a profile. I had a batch of the the Kenya Gakui Peaberry (a phenomenal coffee in so many ways) that I dropped too early and left underdeveloped. I was willing to risk tossing the batch out, so instead I decided to experiment. I literally re-charged the beans back into the drum once I re-established my desired charge temp,(so the beans were actually room temp by that point) and proceeded to manipulate the profile a second time. This led to truly explosive flavor strength, no loss of brightness, no roasty defects, just intensely, brilliant sweet coffee. It may not be the best coffee I've ever brewed (even though it's extremely high up there too) but it was without a doubt, the finest roast I've ever crafted.


With experiments like that in mind, I am going to try something similar, albeit a little different and invite others to try and report on their findings, both good/bad or indifferent. I'd like to see a roast profile of a high quality green, that is charged into the roaster at a dramatically lower ET, like by 100°F lower or even more. With the goal of a very, very gentle slow drying period till the greens are a light golden tan color, then dropped. Bean pile temps will vary, so sensory analysis will be more a key. But let your charge rest while you re-establish your desired charge temp like you normally would. Re-charge the roast and aim for a stretch of your maillard phase pre-crack. Then end your roast at your desired finish temp, but for this experiment, aim for a short development phase post 1C. I believe this is ideal for this sort of experiment. Please don't drag your finish for 3 minutes.

Share your findings here, if you choose to participate. The exact initial charge temp is completely relative to your system only. Ideally, you don't want a fast drying phase. You don't want to develop the surface of the bean to any degree further than the center (at least that's the aim).

Something like this has too many variables to nail down, especially given that it will be done on different coffees. So do this with a coffee you know and like and have a traditional roast to compare it to. This more than anything, will give information as to the effects this has on the coffee, so the results are unique to each person's coffee and profiles.

Tom,

I like this a lot. This was a good wake up post for me, I think I've been sticking to the tried and tested a little too much recently. I have been intrigued by the double roasting idea for a while but never actually tried it. On the road for work for a couple of weeks but look forward to posting some findings after that.

Thanks.

I'll be looking forward to hearing your thoughts!

I seriously doubt it will be a positive result across a wide spectrum of coffees, but I think there's potential for something impressive for a good clean washed coffee. A controlled fluid bed roaster (wink wink Marshall) would be fun to try it on too. The variability of what each person determines "yellow" or "tan" will affect the results, so I hope folks play along for a little while before we find some conclusions.

Ideally, the profile will have- from the re-charge, a drawn out "ramp" thru to 1Cs, and a very short finish. I'm thinking this approach would increase solubility of light roasted coffee, with a greater "sweet spot" of bean development without tipping either into underdeveloped or too roasty.

Glad to see someone experimenting with this technique!
This is covered in my 800n roaster manual:

"If you prefer to double roast your coffee, you will have to stop roasting when Dehydration is done. Cool down the beans first. Then RELOAD the dehydrated beans into the roasting drum, and re-run the roasting steps"

I'll try this out next time the roaster gets fired up.

AFAIK, the double roast technique is evolved from Japan in early days. It is said that the design of old roasters was not efficiently ventilated as the design of new generation roasters. Those old roasters suffered from too long roast time, and the high heat applied in early roasting phase would cause scorch and uneven roast. After drying the bean in the first roast, double roast effectively reduces the required overall second roast time, and the beans could still be evenly developed. This style usually let the bean rest in room temperature overnight after the first roast to re-establish the moister equilibration across the inner and outer bean. It is said that it scarifies some origin characteristic flavors for a mild and smooth mouth feel.

Nowadays the double roast is not popular, because it needs more operating time, effort & fuel. With improved machine design, even roasting is no longer an issue in the [high heat/short roast time] approach. Many years ago when I had a power outage halfway a roast with Behmor, I managed to salvage a batch by double roast, and this is the reason I dig into the above story. Taiwan got the influence from Japan, and I guess this is the reason Hank has the double roasting technique written in his 800N manual.

It should be noted that, in early days, a roast master won't have the luxury to start with the best green beans, and the flavors of different origins & estates were not as emphasized as today. The double roast can smooth out minor edges, as the Importance of the Roaster at Controls. I haven't thought of double roasting a good clean washed coffee in my current setting. It's an interesting experiment.

This sounds like something i need to follow up on immediately...perhaps exactly what i needed based on all these posts. Going to go set up part 1 right now.

Though...the first roast...what would
Be a target time? 10 minute to complete drying...or doesn't matter.

To that point, if that concept holds true about the japanese origins, couldnt the same thing be done by drying in the oven, cooling and then roasting?

Originally, I thought of oven drying, but realized there'd likely be spots of greater heat conduction where the beans are sitting on the pan. Using the gear we already have set up might be all we need to explore this method. I'd propose that someone with a very responsive fluid bed roaster that can really put the spurs to the beans without having to worry about waiting for the thermal mass/soak effect of a traditional drum roaster, might not even need to end the roast and re-charge. They can likely max out the heat after a slow, very low temp "drying" period.

As far as target time, I'm only proposing aiming for a 5-6 minute period max. Any time heat is being applied to green coffee, reactions are either occurring, or their precursor effects are set in place. Meaning, you likely can't get away with a 10 minute period of just drying the beans without potentially baking out something important. But that's all conjecture at this point.

Thanks for the quick response. Dont forget, i just have a ghetto stovetop
Rig as is which is why the comments on the origins piqued my interest that i set up and am heating the air in my pot in my garage at 1am:)

I guess i was expecting a longer time bc of the idea that lesser equipment would need less heat to prevent scorching, which would take longer, butni understand now, I can apply more heat early but if i dont take them i not be able to lower the pots temp fast enough to prevent scorching after drying, hence the need to either go low and slow or pull

EDIT: I will call this a test run on behalf of us stovetop users...must be some out there reading

I ran two batches to test, both at 255 g of Datterra Sunrise blend.

Batch 1:

Settings:started at power of 5, dropped to 3, then 1, then off for the very end to coast into the end of drying and help me dump
Time: 4min 55 seconds end of drying phase
Process: See above. Dropped at 150 as the smoke and scent changed.,
Notes: Its clear that some of the beans in this blend did go a bit beyond the drying phase, but no burns and overall very similar coloration, but different size/shapes of the various beans do look a bit different, more so than I really expected.


Batch 2:

Settings: hot air, power lvl 3 until mid way 1st c then 2 and 1
Time: End of drying phase 8min 43 seconds, drop at 20minutes 53s
Process:
Hot air until 110C
Set to 3 and leave
first audible snap at 1534 and 201c Change to 2 halfway through, shortly after to 1
Last audible snap around 1745, but other changes seemed to take place around 1830 and 208
Pulled at 20 minutes 53 seconds 213C

Will do some amateurish cuppings tomorrow night and then v60 the following morning and sip them both all the way to work
Notes: Probe read some fluctuating between 212 and 213 before dropping, hopefully it didnt start to stall out for too long, but my probe is very inaccurate and inconsistent over 200, my better probe broke recently. Very consistent and light brown coloration with no mottled splotchiness.

This is a pretty cool idea. Will a Behmor qualify for this experiment?

Give it a try. Maybe, who knows? You might be better suited if you can control it like the latest versions, but the proof will be in the cup. My only caution will be this: if you do it and the results aren't impressing you, it may not speak to what other's are finding with more agile roasters. I made many delicious roasts with my Behmor before I sold it. I just got sick of the fiddly nature and lack of true control. But give it a try and let us know.