how to roast coffee beans in an oven, education and you may see me at roasterguild events as well. i'm on the executive council of the roaster's guild.
joe and i discussed it, and we're moving to a new project, roaster school, where joe is going to help us take a deeper dive onroasting segments. we want to give you the science, the principles, and theapplication behind roasting with your coffee roaster. joe is going to be telling us items thatare going to help you with whatever manufacturer and the roaster that you'reworking with so whether you're on the north or adeidrich those principles and science and application will help us improve ourcoffees. joe thought we'd start out today with turning point. joe usesanother term for it...
so, i was i was kind of only focusing on one thing really well at a time and shorting the other so today we're going to focus on onlyone thing; and that is teaching you about the turn around. so the turning point is that point inwhich when you drop the coffee into your drum you see your temperature if you'regraphing a temperature stop and turn around so this point right here. i feel likethere and i hear a lot of misconceptions about what exactly is taking place here.so i really wanted to get into the nitty-gritty and start with this andthen in our consecutive classes that we'll have together we're going to movealong the chain of how the roast develops.
can you see how wonderful i draw?
most drums, you're somewhere in the rangebetween 375â° and 425â°, okay? it depends on your probes, itdepends on what size drum, and it depends on how hot you want that drum. okay? so let's just pretend this is 400,â°because that is a general range - okay? at some point, when you add in thecoffee you're going to see the coffee is thengoing to pull against this temperature and it's going to pull it down and thenthey're going to reach an equilibrium but i don't want you to think about itand being like your coffee is 400â° and then it drops in temperatureand comes back up. this - all of this information right here -
all of this is actually noise - it's notreal. okay? what is really happening is yourdrum is at 400 degrees and your coffee is at room temperature, okay? whatever temperature your coffee was when you put it into the drum. and what's really happening to your coffee's temperature is it is moving upward - ever marching upward from the time that youput it into the drum. okay. unless you do something and ithappens to fall stagnant along the roast somewhere, which we don't want to have happen.but it's ever marching upward, okay? so think about it in these terms. nowyour relationships matter, okay?
in life and in coffee. your relationship between thetemperature of your drum, the temperature of your coffee as you put the coffeeinto the drum, the size of your batch - so how much does that batch weigh? - and thedensity of your coffee, ok? so if i have a drum that has thecapacity for - just for our sake let's say... well what size drum you want to workwith?
about eighty percent capacity, whichcapacity this equals 2.2 046 pounds, so let's say we're going to shoot foreighty percent. let's just say we're doing - let's just say .8 kilos. okay, and then you can divide that numberout at home for fun. i'm not going to do it in my head. so you're putting in your eight - your.8 kilos okay, and that .8 kilo is starting at roomtemperature - let's just say 75 degrees, all right? ifyour drum has been sitting at 400
degrees for 20 minutes, 10 minutes - ifit's stably at 400 degrees - then your turn around on that coffee at .8 kilos if all of these things are the same, thatturnaround should be the same every single time that you roast that coffee.if all of your variables are the same. if your airflow is the same, if your gasis in the same position, if it's the same coffee, if it's the same temperature ofyour drum, same temperature of your coffee, and same weight. if something changes for your coffee,then you know that there is something off. something is off somewhere.generally what i see is people are
turning their drums on and trying to getto this temperature far too quickly, because they think that they need todrop at 400 degrees. so you get the drum up to 400 degrees,and then you drive your coffee in. well that doesn't work, because your drumhasn't fully absorbed all of that heat and held that heat at that temperature. so even though your probe may be showingyou that you're at 400 degrees, the drum is still on its way ofcatching up with that. that 400 degrees is only at that site where you have yourtemperature probe, and the rest of the drums still needs to get hot, okay?
now, this is where it starts to geta little complicated, is when you change which coffee you're dropping this amount. what irecommend for you if you are new to roasting is use your full charge, whichis generally .8 or eighty percent of what the roaster manufacturer saysthe roast is, because this gives you a lot of leeway to turn your gas up andnot flatten it out. if you start with a full load and you get behind, you don'treally have the momentum to get that forward for where you need to go. so i dorecommend starting at about eighty percent capacity, and then i recommend withall of your coffees try to keep that
same charge until you really understandthe fundamentals of your roaster. so then if i take another coffee, andthat coffee is more dense - which what i mean by that is, every seed weighs more.so whenever you weigh out your .8 kilos, you're actually weighing out lesscoffee. you'll see in the, in the bucket that you're weighing it in, it'll be stunted.it will be a little less, will be less material. so what that means is is two things. thefirst thing is, in your drum.. this is your drum. your drum has thesethings that fly off of it that toss
coffee about, right? as your drum is rotating, let's say it'srotating this way, your coffee is collecting, and yourcoffee will start collecting actually collects right up here. okay? but it's also tossing about, tossingabout, tossing about. if i have less coffee in that drum, the mass of thatcoffee is going to be more diffuse in that space, so the dense coffee is goingto come in contact with metal and other coffee seeds less often. okay. that also means that my coffee seedis going to dry out a little bit more
quickly on the outside, because it'sexposed to more air that's taking that moisture off of the coffee. so what ends up happening also alongwith that, where my probe is, wherever that probe is in that drum it's getting hit by less coffee, so it'sshowing that my coffee is actually having a smaller effect on this number, okay? so if it's having a smaller effect, thatmeans that it's going to change the way that that temperature is correspondingto my turnaround, okay? so it it may show you
that you are turning around more quicklyor most slowly depending on the density of the coffeethat you're putting in there, because the mass of .8 kilos could be anynumber of beans. it could be two million beans, it could be 1.5 million beans. itjust all depends on your roaster. so you want to think about on how thesethings correspond together. so if you are changing your coffee, it is very important for you tounderstand where your turnaround needs to be for that particular coffee. and ican't tell you you need to be at a hundred and seventy-five degreesfahrenheit on your drum for this
particular coffee, because every coffeeis going to have its own turn around temperature. so let'ssimplify this. to simplify this and not get caught up in the weeds of all ofthis, it's very important that you keep trackof your roasts, okay, that you pay attention to your starttemp, that you pay attention to your bean's temperature, your coffee's temperature, that you try tokeep track of a very thoughtful and consistent batch size for whatevercoffees that you're using, and then pay attention to where that coffee naturallywants to turn around at a general drop temperature.
so instead of messing with your coffeeand saying, "well, i'm going to do, i'm going to do sixty percent batch today, and ithink that i need to then lower my charge down to 395 and then try to findout where my turn around temperature was whenever i had a point, you know, or an eighty percent batch at400," that's all out the window. even thoughyou're turning around at the same temperature, by pulling allthose pulleys and levers and making that happen, that doesn't necessarily mean that aminute, two minutes, three minutes down the road you're going to be on the samepath.
okay, so keep these things as consistent asyou can until you fully understand how each coffee is turning around, okay? if your coffee is turning around morequickly, then your coffee is probably a little bit less dense. it's going to take on the heat morequickly, and it's going to move through the roast a lot more quickly. if yourcoffee is turning around a little bit later, then your coffee is probably alittle bit more dense. it's not taking on the heat as quickly, and that's okay. a lower density coffee needs a littlebit more time to absorb that heat, both
because of the structure of the coffeeand because of the nature of how that coffee is in the drum, okay? so your more dense coffee is goingto pull harder against this, and it's going to drop down further away. this distance is not going to be verysignificant, but it still matters. and why does it matter? well, if first crackhappens at a particular temperature, which it does, then if this is fivedegrees lower, then it's going to take you that amount of time to get to firstcrack. it's going to be a longer roastautomatically, and you want to make sure
that you're not rushing it as you're getting it out ofyour turn around. so the way that i look at this, and you've heard this analogyprobably before, is this is kind of like a launching padto the speed that your roast is then going to move forward. and so if yourcoffee is coming down on this launching pad on too hard, then it's not going tobe able to pull up out of that turn around. if your coffee is coming down andgetting stopped before that launching pad, it's going to just blast off, andit's going to take off very quickly. okay, any questions?
we can't emphasize enough please be consistent until you learnyour roaster. time after time after time, use that same charge size. joe's talkedabout most of the roasters out there - sweet spot about 75 to 80 percent. forthose of you that are on north your full charge size should be one kilo. it's not down in the eighty percentrange. it is a full kilo or full 500 grams. that's one thing. joe, would you definedensity? and you say one has low density and one has high density,
what does the density of a coffee mean?
the exact same seed size, but one mayweigh more than the other because it has more densely compact carbohydrates, you know, all of the other sugars, all theother things that go into that coffee seed that you're going to turn intoflavor. the moisture is kind of insignificant as it pertains to thedensity of the coffee. moisture is kind of static. so the actual compounds that you'regoing to be converting into flavor are what build up the density of the coffee.
around at a lower point than coffeeswith a lower density.
will take will move much more slowlywith the same amount of energy applied. so again you're starting herewith your coffee, so if you have a very high density coffee, it's going to take a lot more energy tomove it forward. now automatically that makes me think from like a physics standpoint, then thatmeans i should be at 410. or that means i should be hitting my my throttleharder. instead of being at four inches of gas ineed to be a 5 inches of gas to get that moving.
well if you do that, you're going toscorch your denser coffee. it's going to burn the outside without that heatgetting a chance to penetrate. that's why i say no matter the density,while you're learning the process of learning your machine and learning thatcoffee, try to start with a consistenttemperature here, a consistent temperature here, and a consistent weight.and it may be the case that eventually you get to a place where instead ofusing a weight n, you're using a mass n. so like a particular size ona graduated cylinder of some sort - that could be the case, but the geekier youget with all of these things, and the
more you start going down rabbit holes, the more likely you are going to missthe forest for the trees, and you're going to get into the weeds, and if youjust pull back and keep this stuff as simple as possible and then see howyour coffee roaster responds, and then you respond to that information in a clear level-headed way, you're goingto get a much better result out of your roaster.
what do i do with it?
going through the next segment of ourclasses over the coming months, and we're covering more and more of this chart,then when you get to this and unfortunately it's a little bit morelike this, then you can go back down the chart and you can find exactly the pointwhere something went wrong. but if i've changed this, if i've changed this, if i've changedthis, if i changed air flow if, i've changed gas if, i've made all of theseadjustments, then how do i know where exactly i need to make a change to fixanything? i don't. so you have to start withsomething that's very cut and dry, very simplistic, and even though this looksvery simplistic
starting in this way, this isactually very complex, and it's setting you up for success. it's just like you're building ahouse, and if you look at a blueprint for building a house, the basements of all of these differenthouses look very simplistic, but they're simplistic because they're tried andtrue, and we know that the structure that we can build on top of that candiversify all different ways. but if their foundation, which is the beginningpart of that roast and the turn around, if that is in place, then we can moveforward and start getting a little bit
more creative with the roast a littlefurther on.
starting with a clear foundation willhelp you get to that point more consistently. if you have a coffee that'san odd duck, that for whatever reason within this system you know that your roaster is heated andstable, you know that your ambient temperature in the room is stable, you know that you're roasting the sameamount of coffee, but for whatever reason it's dropping well outside of a reasonable limit, thentreat that coffee as that coffee is responding within that system, okay?
if you go and make an overadjustfor that coffee being outside of spec, and try to get it inside of spec, thenyou're double forcing that coffee. that coffee is telling you that it'sdifferent. there's something different about itthat you have not experienced before. and so then by nature of that, thatshould tell you "i don't know this coffee." but if you respond to that by saying "buti'm going to treat it like every other coffee, get it to file and rank," then you areautomatically mistreating that coffee. so if it starts falling out of rank, thenyou need to set your parameters different. if that coffee doesn't crackon time, if it cracks at 10 minutes as
opposed to eight and a half minutes, it's okay. get to the end of that roast by following that coffee's lead, bymaking your adjustments according to where your turn around temperature was,and then make all of the consecutive adjustments to follow that to where ifnormally it takes four minutes after turn around for yellow but turn aroundhappens at two minutes instead of a minute and a half, then go ahead and makean adjustment and say "now i want to have yellow or my coffee fully dried at fourand a half minutes instead of four, and then i'm going to push my first crackaccordingly."
and then get to where you can tasteit, and taste it in the same way that you taste it every other time. make sure that all of those things, allof your variables, are consistent so that then you can go back and you can say, "youknow what? that tasted really great. i'm happy with that roast, and it's fine. i hadto break the rules."
cutting gas at the first minute, first minute and a half until you hit turning point. harrison boyd is wondering, is that part ofthis thought process, does that play in? and to that same point, just to jump on to another question, how do you react to gas and airflow throughout this turning point?
because i'm trying to drive two things:that core temperature to the same temperature as the outside, and i want toactivate the water. so i want that bean just taking in the heat, so i use a minutewith burners off. joe roasts differently, and again we're talking about roaster'spreference. so turning point doesn't govern mereigniting the burners - time does.
i've roasted here has been the firsttime with the coffee and the first time on that machine with that coffee.
coming out of that turn.
so, whether it's electric or whether it'sgas, it's still energy coming from heat, so the basic principles of this shouldapply, regardless of what kind of heat source that you have. the electricburner is heating the metal, and the metal is heating the coffee. the electricburner is heating the air, and the air is heating the coffee. so it's just all a matter of thatparticular system seeing how the coffee reacts within thatsystem. and if you have electric, or if you have gas, or if you're roasting on anair roaster, it's about setting base parameters tostart, with your batch size, temperature
of your equipment, and the temperatureof the coffee going in, and then how much gas or how many amps you're going to apply to that coffee after that.
there is the humidity of the coffeeitself - which i don't know if that's the exact question. i think that's what thequestion's applying to?
however, we can measure both through thedensity check on the coffee and barometric pressure within ourenvironment. so, if you're roasting on a small roasterlike this, barometric pressure is going to be kindof a non-issue, and i think that it's something that we really shouldn't befocusing on. if you're roasting in a very large roaster, the pressure pushing downon that roast is going to have a major change to how that roaster will roast. andso that in a large roast setting will affect the way that you play with airflow, okay? but i don't think that that appliesto anything above, say a 70 kilo drum or beyond.
if you are seeing changes in the coffee due to the moisture in the coffee or themoisture in the air, i would recommend looking at some othertriangulating data to make sure that you're not making a corollary judgmentas opposed to an actual sound judgment. i think that baristas do this all thetime. they see that their coffee shop dries out all of a sudden, and they say"oh the you know humidity in the room changed, so it put my grind off." thatis a correlation, that's not a causation. we know now thatthat is not true.
thing about humidity and coffee and thesame thing about humidity in the air but now i know better. that doesn't count to us. okay? you'retoo small, and the variables involved there are throwing you way off.sorry to interrupt. try to keep these consistent untilyou're learning that roaster. the lower the turning point, the denser the bean, the tighter that cell is within that bean. if you get a really sharp spike coming at a turning point, you may have too much gas. too heavy of afoot on the pedal. so pay attention to the sharp turning points. what else did you want to emphasize thati talked about today? but at the end of the day, tasteyour coffee, and if there's something wrong, and you've done your homework to whereyou have managed everything, then you should be able to find thatvariable that was off. and if you don't, that means that there are probably a lotof other variables that you don't know about, so tune in to future events from us, andhopefully we'll go over some of that. look at that - it's a beautiful bear with the twin cities skyline. his wife hates it,you all love it. perfect. hold up the mic for the camera. three, two...
