nzbbqroaster Senior Member Joined: 6 May 2012 Posts: 3 Location: New Zealand Expertise: I like coffee
Espresso: chimbali 3 group basic... Grinder: Mazza Super Jolly Roaster: BBQ
Posted Sun May 6, 2012, 10:37pm Subject: bbq roasting environment temps
Hello Im brand new to this forum so excuse me if this is off topic. I live in Nz and have been playing around with my home made perforated drum bbq roaster similar to an RK drum. After about 4 months of playing and following anything i can find on the internet about profiles and environ temps I have decided lower is better. I just cant understand some of the advice on the sites for roasting in a bbq drum at higher temps with more beans, it just tates awful in the cup when i try. They advocate that as bean load increases above 1 pound, you should increase temps. I tryed it, if go above 230 celcius you will either get carbon tastes or very rancid tastes under pressure through a good esspresso machine. (tastes lke blue smoke out of a tailpipe of a car). Now im no expert but I found that if you icrease bean load above 1 pound, first and second crack is pushed way back in time at same temp, so to end on time they increase temps, but that destroys the taste no matter what. If you ramp up to 250 to 260 even though you have a few pounds in the drum the bean still comes into contact at some point with that temp and bad things happen. If you do two tests, one with a pound and dont go over 230 celcius, roast mainly at 220, and one at 260 celcius with 2 or three pounds the lower temp roast is far superior. So to increase loading you have to bring in convection heat somehow and try to replicate what happens in a big roaster with more thermal mass where they can get heat throgh the beans at those lower temps. I welded on some small blades around the drum and this helped heaps, i could tell by the less time taken to first with one pound, then I could add beans keep same lower temps untill im on the verge of an acceptable 1st crack time. Can someone add some light why the people out there roasting with bbqs, advocate increasing temps with bean loads, it just does not work period, unless your using the coffee for a dripper and want carbon cigarette burnt oil tastes. Or have i completely missed the point here and am missing something major
Posted Sun May 13, 2012, 10:48pm Subject: Re: bbq roasting environment temps
Hello and welcome to CG!
Your experience really parallels mine. Nice write up.
I've long settled on 1lb batches in my "4lb" roasting drum which allows me to keep the temps reasonably low.
I agree with your assessments on BBQ drum roasting, we just don't have the air flow to really properly handle larger bean loads like the professional drum roasters do.
RichardCoffee Senior Member Joined: 2 Dec 2010 Posts: 96 Location: Long Beach Expertise: I live coffee
Espresso: gaggia baby twin, mini... Grinder: fiorenzato pietro 63mm,... Roaster: weber grill with rk drum
Posted Sun May 20, 2012, 7:58pm Subject: Re: bbq roasting environment temps
I agree in part, although I'd like to know more about your set up. What grill are you using? What is your time to first crack? - second? What speed motor? Where are you measuring your temperature and with what?
I have a 4 pound RK with a 36000 btu weber grill and a 60 rpm motor. The weber is soundly constructed and provides the opportunity to open the front doors and provide an induced draft of sorts.
I have decided to limit my roasts to 2 pounds because I can get to first crack in around 10 minutes and second (if I want to go there in about 14. Larger roasts simply require too long and too high temps, although I have had pretty good success with 3 pound roasts. The idea of 8 or even 20 pound roasts seems to defy logic for me, even though some folks are doing it I guess.
I measure temps in 2 places with different thermometers. One thermometer is in the hood towards the upper half of the drum. That's the one I use to control my roast. For a 2 pound roast I will load around 500 F., the temp drops to 420 or so and works back up to 500 by about 5 or 6 minutes into the roast. Then, I'll let the temp climb to no higher than 525 till 1st crack and immediately drop the temp to 470 where I hold it till I stop the roast.
The other thermometer is situated closer to the bottom front of the drum. It is the digital that Sweet Maria's sells. The thermocouple on that one is exposed pretty directly to the flame from the front burner and as a result reads about 100 degrees higher than the top thermometer. Taken together I have a good idea of where I stand in my roast. Also, the bottom one gives me an early warning in the event that I run out of gas.
Cool glad of a response had not checked as thought this topic was of little interest. Yes i can confirm that I need to keep my drum less than 1 pound about 400 Gramms perfect. I have made a million adaptions that all have roasting differences and taste differences. I am a roaster that roasts for flavour and desirable flavours in the cup only and trying to eliminate the undesirables. It all comes out after day 3 with a good grind to push nice fast drip into flowing crema on the chimbali. Now why I say that is you have to be drinking everything you roast and push it under pressure like a true barista would to understand if your change had a positive or negative flavour outcome. If what you did was wrong. (eg profile, temp, structural,vents,steel mass adjustment) then you will be sure to taste that change immediately under a proper pressurized esspresso but you will hardly detect a thing with plunger etc. I found this. 3 things have to be achieved. 1, roast needs to end max 17 mins preferable 15.5 to 16 for full flavours, 2. Drying slow and ramp evenly to first crack but not exceeding 215 ( all my temps in centigrade) 3. Try to have at least 3.5 mins to beginning of second from first,not to concerned with my profile here as I know temps increase and don't stall by how long it takes. If the gap here is fast flavours like nutty, earthy are goons
Now il tell you how I do that as 1, 2 and 3 all fight each other. Bottom line keep temps down and try to run it like a probat profile smooth. Drop beans until you can hit first crack at about 12 mins by going real slow to 5mins (dry) cross at et 200 at about 6 mins and slowly increase to about 215 at first crack at no more than 12 mins. If you can't do this with current setup then dump some beans until you can. Second trick how to get there with so much less heat then make it glide slowly to second for 3.5 mins with such little in the drum( hard to do). This is how I solve those two probs. I use almost direct heat under the drum with two burners at idle to first and I have the other two burners that are not under the drum running under thick 6mm steel plate slotted. What I do is control the profile to first by setting the outside burners ( or indirect heat) to a medium setting while the burners directly under the drum (direct) are on idle. What that allows you to do is two things in the roast. One is that you don't have to touch the idle direct burners under the drum just adjust the ones outside the drum and play until you find a setting where the roaster is now set on a path smooth heat rise all the way to first, then the clever part, right on first pop shut down the direct heat burners under the drum and quickly set the outside burners burning through the plates to full. This does two things, slows the roast perfectly to get the gap to second right and also stops putting direct heat on the beans and coasts them to develop indirect heat flavour. It works good
Now so you understand. I have a 4 burner BBQ. Drum is almost same as rk but only about half the width of a 4 burner BBQ about 350mm I think. So I mount it in the middle right over the centre two burners( what I referred to as direct heat). The two burners either side of the drum that don't lie directly under it when mounted on the spit are the indirect heat ones. These are what I'm referring to as indirect and are used for controlling the roast. What you need to do is play around with the plates covering these and the slits in them until you get the roadster setup so that when these are set to about a third power the roast temps glide along a nice temp profile to first crack. It's all in the roaster setup, I don't need to touch a thing now after drying for 4 mins with just 2 burners I switch to 4 burners (under drum idle) then set the indirect ones to a third and it just profiles perfectly to first at that setting and temps go no more than 215 at first. Then as I explained shut the centre ones off completely so no more direct and full power on the outside (full indirect). It will just drop temp 5 degrees and temps just cruise at about 205 all the way to second at 3.5 mins later. I know it has not stalled as it hits second in nice time but good flavours come throgh. I know this is very tech but it took many 100 kg to work this out. I started like Ll the sites suggested with these massive temps and the coffee was crap, literally awful no origin acidity or any balance at all.
I use a thermocouple as you all do located front lower side of drum wrapped in a bit of tin foil. Also I use a 12 volt Toyota window wiper motor as a driving method, this turns at about 70 to 80 rpm, I found this slightly higher rpm good for getting heat into beans. This became critical when I started to attemp to achieve 1, 2 and 3 above all at low temp. Could not get to first for 15 mins with even small amount of beans. Trick is weld some small stainless paddles on outside of drum and small vents in back of shielding and high rpm with idle direct heat under drum all helps get there on time with a reasonable amount of beans in the drum. I can post photos for those interested. Think I can nearly achieve 450 Gramms now in 16 mins using my temp profile which is no different than a commercial probat profile at all, in fact it's totally normal, what is not totally normal and what I have had no success with is roasting at 500f like some do. They should roast less and try my tricks to get flavorful coffee and accept that to do this with big quantities it's the roaster design and mass and you really need a probat or similar with its thermal mass and fans and convective heat transfer at sensible temps
Thanks again looking forward to feedback, this has taken me most of night to type and don't have time for edits so apologies for that
Hi. Can I suggest something. Just try this for fun if you will. Throw out everything you have been doing and just try this. Bring drum to 200( all in centigrade sorry) and load beans. Drop power to idle on one possibly two burners. I know you will not feel comfortable tryin but give it a go. Let the et sit at 170 for about 3 mins (drying) then slowly get the roast on the way. Try to find a setting now by either lighing another burner on idle or turning all on at low setting and try to hot first crack at no more than 215 centigrade in 12 mins. Then somehow sut some heat off straight under the drum and put more heat on the burners not under the drum in the BBQ, heat may drop and only sit on 205 but just let it sit there and glide to second 3.5 mins later and dump 10 secs after first clicks of second and cool. Wait 2 days and pull a shot on a nice machine with correct water temps and grind. You will get s lovely cup of mixed origins flavours possible nuts and earthy caramel that you have not tasted, hopefully with only pleasant light roasting flavour notes coming through from the side but nothing unpleasant. I guarantee it will taste nothing like you have been getting
Good luck I'm hoping you find some great flavours in the cup
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