Ep #1 – Turning Point

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<Dave> Hi, I’m Dave Borton Welcome to…Roaster School! I’m Dave Borton, Mill City Roasters, along with…

<Joe> Joe Morocco from Cafe Imports.

<Dave> Joe, what’s your position over there?

<Joe> I am one of the senior sales representatives and also the director of education and you may see me at Roasters Guild events as well. I’m on the Executive Council of the Roaster’s Guild.

<Dave> Very good. Like we said: welcome to Roaster School.We took a look at your feedback, we took a look at our own videos,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 on roasting segments. We want to give you the science, the principles, and the application behind roasting with your coffee roaster.Joe is going to be telling us items that are going to help you with whatever manufacturer and the roaster that you’re working with so whether you’re on the North or diedrich those principles and science and application will help us improve our coffees. Joe thought we’d start out today with turning point. Joe uses another term for it…

<Joe> Turn around sometimes is also used

<Dave> Yeah, so they’re both applicable but with that that’s the low point after you charge your roaster and those greens drop down on their migration north so without any further ado, Joe, how about it?

<Joe> Sounds good! Yes, as they said you know, our old format we spend time roasting a coffee and you had the opportunity to buy into that coffee if you would like however we found that a lot of times i would get distracted by roasting or distracted by a question  or trying to explain

<Dave> Or distracted by Dave.

<Joe> Or distracted by Dave.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 only one thing; and that is teaching you about the turn around.So the turning point is that point in which when you drop the coffee into your drum you see your temperature if you’re graphing a temperature stop and turn around so this point right here. I feel like there 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 and then in our consecutive classes that we’ll have together we’re going to move along the chain of how the roast develops.

<Dave> Joe, does the supplied every drum roaster out there?

<Joe> This will apply not only to every drum roaster but generally every roaster that is out there if you have the ability to collect your temperature data.If you’re collecting your temperature data I guess this is the first step, you want to have some kind of chart system.Whether it’s an actual graph that you are charting out on paper or whether it is a system of boxes where you’ll have your chart like this and then you have your temperature change and you have your time  and you can just write each one into each graph line.Can you see how wonderful I draw?

<Dave> We have a lot to look forward to.

<Joe> So then you can take every 30 seconds or every minute whatever you want to do- and you can collect your data of what time is it and what temperature is it and then you can write that on a graph so this would be your temperature and this would be your time.

<Dave> Going this way?

<Joe> That’s right. So time ever marches forward, but your  temperature is going to find a particular place along that graph.So whenever you put your coffee into the drum,what is happening is: your drum is at a certain temperature. Generally on most drums, you’re somewhere in the range between 375° and 425°, okay?It depends on your probes, it depends on what size drum, and it depends on how hot you want that drum. Okay?So let’s just pretend this is 400,°because that is a general range – okay?At some point, when you add in the coffee you’re going to see the coffee is then going to pull against this temperature and it’s going to pull it down and then they’re going to reach an equilibrium but I don’t want you to think about it and being like your coffee is 400°and then it drops in temperature and comes back up. This – all of this information right here -All of this is actually noise – it’s not real.Okay?  What is really happening is your drum 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 you put it into the drum.Okay. Unless you do something and it happens 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. Now Your relationships matter, okay?In life and in coffee.Your relationship between the temperature of your drum, the temperature of your coffee as you put the coffee into the drum, the size of your batch -so how much does that batch weigh? – and the density of your coffee, ok?So if I have a drum that has the capacity for – just for our sake let’s say…well what size drum you want to work with?

<Dave> 1k

<Joe> One kilo drum, ok.

<Dave> Explain density.

<Joe> If I have a one-kilo drum – and i’ll explain that density here in just a moment a little bit more in depth.So here is a about eighty percent capacity, which capacity this equals 2.2 046 pounds,so let’s say we’re going to shoot for eighty percent. Let’s just say we’re doing – let’s just say .8 kilos.Okay, and then you can divide that number out 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 room temperature -let’s just say 75 degrees, all right? If Your drum has been sitting at 400 degrees for 20 minutes, 10 minutes – if it’s stably at 400 degrees – then your turn around on that coffee at .8 kilos if all of these things are the same, that turnaround 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 gas is in the same position, if it’s the same coffee, if it’s the same temperature of your 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 get to this temperature far too quickly,because they think that they need to drop 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 drum hasn’t fully absorbed all of that heat and held that heat at that temperature.So even though your probe may be showing you that you’re at 400 degrees,the drum is still on its way of catching up with that. That 400 degrees is only at that site where you have your temperature probe, and the rest of the drums still needs to get hot, okay?Now, this is where it starts to get a little complicated, is when you change which coffee you’re dropping this amount.What I Recommend for you if you are new to roasting is use your full charge, which is generally .8 or eighty percent of what the roaster manufacturer says the roast is, because this gives you a lot of leeway to turn your gas up and not flatten it out. If you start with a full load and you get behind, you don’t really have the momentum to get that forward for where you need to go. So I do recommend starting at about eighty percent capacity, and then I recommend with all of your coffees try to keep that same charge until you really understand the fundamentals of your roaster.So then if I take another coffee, and that 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 less coffee. 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. The First thing is, in your drum..This is your drum. Your drum has these things that fly off of it that toss coffee about, right?As your drum is rotating, let’s say it’s rotating this way,your coffee is collecting, and your coffee will start collecting actually collection right up here.Okay? But it’s also tossing about, tossing about, tossing about. If I have less coffee in that drum, the mass of that coffee is going to be more diffuse in that space, so the dense coffee is going to come in contact with metal and other coffee seeds less often.Okay. That also means that my coffee seed is going to dry out a little bit more quickly on the outside, because it’s exposed to more air that’s taking that moisture off of the coffee.So what ends up happening also along with that, where my probe is, wherever that probe is in that drum it’s getting hit by less coffee, so it’s showing that my coffee is actually having a smaller effect on this number, okay?So if it’s having a smaller effect, that means that it’s going to change the way that that temperature is corresponding to my turnaround, okay?So it it may show you that you are turning around more quickly or most slowly depending on the density of the coffee that you’re putting in there, because the mass of .8 kilos could be any number of beans. It could be two million beans, it could be 1.5 million beans. It just all depends on your roaster.So you want to think about on how these things correspond together. So if you are changing your coffee,it is very important for you to understand where your turnaround needs to be for that particular coffee. And I Can’t tell you you need to be at a hundred and seventy-five degrees Fahrenheit on your drum for this particular coffee, because every coffee is going to have its own turnaround temperature. So let’s simplify this. To simplify this and not get caught up in the weeds of all of this,it’s very important that you keep track of your roasts, okay,that you pay attention to your start temp, that you pay attention to your bean’s temperature,your coffee’s temperature, that you try to keep track of a very thoughtful and consistent batch size for whatever coffees that you’re using, and then pay attention to where that coffee naturally wants to turn around at a general drop temperature.So instead of messing with your coffee and saying, “Well, I’m going to do, I’m going to do sixty percent batch today, and I think that I need to then lower my charge down to 395 and then try to find out where my turn around temperature was whenever I had a point,you know, or an eighty percent match at that’s all out the window. Even though you’re turning around at the same temperature, by pulling all those pulleys and levers and making that happen,that doesn’t necessarily mean that a minute, two minutes, three minutes down the road you’re going to be on the same path. Okay, so keep these things as consistent as you can until you fully understand how each coffee is turning around, okay?If your coffee is turning around more quickly, than your coffee is probably a little bit less dense.It’s going to take on the heat more quickly, and it’s going to move through the roast a lot more quickly. If your coffee is turning around a little bit later, then your coffee is probably a little bit more dense. It’s not taking on the heat as quickly, and that’s okay.A lower density coffee needs a little bit more time to absorb that heat, both because of the structure of the coffee and because of the nature of how that coffee is in the drum, okay?So you’re more dense coffee is going to pull harder against this, and it’s going to drop down further away.This distance is not going to be very significant, but it still matters.And why does it matter? Well, if first crack happens at a particular temperature,which it does, then if this is five degrees lower, then it’s going to take you that amount of time to get to first crack.It’s going to be a longer roast automatically, and you want to make sure that you’re not rushing it as you’re getting it out of your turn around. So the way that I look at this, and you’ve heard this analogy probably before,is this is kind of like a launching pad to the speed that your roast is then going to move forward. And so if your coffee is coming down on this launching pad on too hard, then it’s not going to be able to pull up out of that turn around.If your coffee is coming down and getting stopped before that launching pad,it’s going to just blast off, and it’s going to take off very quickly.Okay, any questions?  

<Dave> Just a quick summary We can’t emphasize enough please be consistent until you learn your roaster. Time after time after time,use that same charge size. Joe’s talked about most of the roasters out there -sweet spot about 75 to 80 percent. For those of you that are on North your full charge size should be one kilo.It’s not down in the eighty percent range. It is a full kilo or full 500 grams.That’s one thing. Joe, would you define density? And you say one has low density and one has high density,what does the density of a coffee mean?

<Joe> It’s your mass over volume. So you can think about it as being if you have two balloons, and they’re both the exact same size, that is your mass. If one of them is filled with water that’s your destiny.It’s a lot more dense. There’s a lot less space in the balloon between molecules, okay?

<Dave> And in the coffee cell what creates that density?  

<Joe> The coffee cell should be more dense based on all of the compounds that that coffee has stored into itself.So it’s not water, so – I know i used the balloon analogy with water – but in a coffee, you could have a coffee that is eleven percent moisture, they could be the exact same seed size, but one may weigh more than the other because it has more densely compact carbohydrates,you know, all of the other sugars, all the other things that go into that coffee seed that you’re going to turn into flavor. The moisture is kind of insignificant as it pertains to the density of the coffee. Moisture is kind of the actual compounds that you’re going to be converting into flavor are what build up the density of the coffee.

<Dave>And if i remember correctly what you said, denser beans, where that cell structure is tighter, are going to turnaround at a lower point than coffee with a lower density.

<Joe> That’s right.

<Dave> Okay.

<Joe> if you think about that in terms of that coffee starting at your roaster has to do more work to get that dense coffee to move forward in it through its heating process. And again that’s because it’s more diffuse in that space and because those denser seeds need more energy in order to get to the same place.If you think about this in terms of movement, if you have a car that weighs a lot and another car that doesn’t weigh a lot,and they have the exact same engine and the same amount of fuel moving them, that very heavy car will take will move much more slowly with 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 to move it forward. Now automatically that makes me think from like a physics standpoint, then that means I should be at 410. Or that means I should be hitting my my throttle harder.Instead of being at four inches of gas i need to be a 5 inches of gas to get that moving.Well if you do that, you’re going to scorch your denser coffee. It’s going to burn the outside without that heat getting 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 that coffee,try to start with a consistent temperature here, a consistent temperature here, and a consistent weight.And it may be the case that eventually you get to a place where instead of using a weight n, you’re using a mass n.So like a particular size on a graduated cylinder of some sort – that could be the case, but the geekier you get with all of these things, and the more you start going down rabbit holes,the more likely you are going to miss the forest for the trees, and you’re going to get into the weeds, and if you just pull back and keep this stuff as simple as possible and then see how your coffee roaster responds, and then you respond to that information in a clear level-headed way, you’re going to get a much better result out of your roaster.

<Dave> Joe, you’ve got a data here,data point here and turning point. How do you use that?Okay, it’s a piece of information. Now that I have that piece of information,what do I do with it?

<Joe> So all of the data that you’re collecting should result in one piece of data that is the most important data.Okay, and that is…does it taste good? Does it make you happy? At the end of the roast is it an aesthetically pleasing roast? So all of this stuff is pointing to this. And how do you know whether or not all of this stuff matters, is by tasting it,by sharing it with friends, by sharing it with coworkers if you’re in a professional setting.Taste, taste, taste, okay? So then when you’re starting with all of this and as we’re going through the next segment of our classes 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 more like this, then you can go back down the chart and you can find exactly the point where something went wrong. But if I’ve Changed this, if I’ve changed this, if I’ve changed this, if I changed air flow if, I’ve changed as if, I’ve made all of these adjustments, then how do I know where exactly I need to make a change to fix anything?I don’t. So you have to start with something that’s very cut and dry, very simplistic, and even though this looks very simplistic starting in this way, this is actually very complex, and it’s setting you up for success.It’s just like you’re building a house, and if you look at a blueprint for building a house,the basements of all of these different houses look very simplistic, but they’re simplistic because they’re tried and true, and we know that the structure that we can build on top of that can diversify all different ways. But if their foundation, which is the beginning part of that roast and the turn around, if that is in place, then we can move forward and start getting a little bit more creative with the roast a little further on.

<Dave> Very good. Nick, questions that have come in from the audience?

<Nick> Oh, absolutely. Yeah, let’s do this. Brian had a question that he rephrased for us.he’s saying if you’re targeting a specific drying temp regardless of turnaround temp, sorry,targeting a specific time phase, is the idea that a lower turnaround temp is now going to result in later milestones okay,or is that something to avoid? I Think you touched on this a little bit – I think just a clearer answer…

<Joe> Okay, so I want to tell you that everything is okay if it results in this.Okay?If it helps your coffee tastes good,then you can feel free to break a rule.Starting with a clear foundation will help you get to that point more consistently. If you have a coffee that’s an odd duck, that for whatever reason within this system you know that your roaster is heated and stable, you know that your ambient temperature in the room is stable,you know that you’re roasting the same amount of coffee, but for whatever reason it’s dropping well outside of a reasonable limit, then treat that coffee as that coffee is responding within that system, okay?If you go and make an over adjust for that coffee being outside of spec,and try to get it inside of spec, then you’re double forcing that coffee. That Coffee is telling you that it’s different.There’s something different about it that you have not experienced before.And so then by nature of that, that should tell you “I don’t know this coffee.”But if you respond to that by saying “but I’m going to treat it like every other coffee,get it to file and rank,” then you are automatically mistreating that coffee. Soif it starts falling out of rank, then you need to set your parameters different. If that coffee doesn’t crack on 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, by making your adjustments according to where your turnaround temperature was,and then make all of the consecutive adjustments to follow that to where it normally it takes four minutes after turn around for yellow but turn around happens at two minutes instead of a minute and a half, then go ahead and make an adjustment and say “Now I want to have yellow or my coffee fully dried at four and a half minutes instead of four, and then I’m going to push my first crack accordingly.”And then get to where you can taste it, and taste it in the same way that you taste it every other time.Make sure that all of those things, all of your variables, are consistent so that then you can go back and you can say, “You Know what? That tasted really great. I’m Happy with that roast, and it’s fine. I had to break the rules.”

<Dave> Joe, as I listen to you, you sound more principles-bound than rules-bound when you roast.

<Joe> Yes.

<Dave> So it’s about staying fluid, open to what the coffee presents rather, than coming at the coffee with a set of rules that you’re going to govern for that roast.

<Joe> That’s right. In starting with a very clear-cut set of rules will actually allow you to be freer later on for the coffee to kind of play within that set, because you’ll know that it’s the coffee that’s making the change,whereas if you don’t start with this,you don’t know if it’s the roaster, the coffee, or you that’s messing with the system up. So If you can eliminate variables as much as possible and get to the coffee itself, then that coffee is going to show you where it kind of needs to go.

<Dave> Very good. Nick,any other questions there?

<Nick> Yes, sir. Let me scroll. Here at Mill City,in the videos that we do, Dave talks a lot about cutting gas at the first minute, first minute and a half until you hit turning point.Harrison Boyd is wondering, is that part of this thought process, does that play in?And to that same point, just to jump onto another question,how do you react to gas and airflow throughout this turning point?

<Dave> I can take it from Mill City. I use a minute.I do not use turning point. Turning Point varies for me – 55 seconds to a minute and ten with full capacity. And That’s just a data point. I file that away mentally and say, “Ooh, this is denser than I thought.” I leave the burners off for that first minute in that I want that bean soaking in every bit of heat,because I’m trying to drive two things:that core temperature to the same temperature as the outside, and I want to activate the water. So I want that bean just taking in the heat, so I use a minute with burners off. Joe roasts differently,and again we’re talking about roaster’s preference.So turning point doesn’t govern mere igniting the burners – time does.

<Joe> And I Would agree with Dave, actually on this.

<Dave> There’s a first.

<Joe> When I am profiling a coffee or I’m Roasting a coffee for the very first time, I will react to how the coffee is turning around with the way that I turn on the gas, and that’s what you’ve seen me do here, because every coffee that I’ve roasted here has been the first time with the coffee and the first time on that machine with that coffee.

<Dave> Right.

<Joe> And many times on the first roast that I’ve done on that machine period. But if I’m in a situation where I have already drawn up a profile,I’ll backtrack that up and get to the point where I’m turning on my gas at the same point every time. But I’ve made I make an adjustment as to how high I Turn on my gas based on the first few times that I roasted, seeing where that turnaround is naturally occurring.

<Dave> Absolutely. And How much gas you’re administration coming out of that turn.

<Joe> Yep. And if I have a sharp turnaround, then I know that the coffee is reacting to the heat in a very fast way,and so that sharp turnaround will tell me that I need less gas whenever I charge my roast. However, if I See a sagging turn around, then that tells me generally that I need a little bit more gas.Another question?

<Nick> Any changes for electric drum roasters for what we’ve talked about today?

<Joe> Electric, light, so you can get a halogen bulb that can drive the roast, air, gas -these are all methods of heating coffee.So, whether it’s electric or whether it’s gas, it’s still energy coming from heat,so the basic principles of this should apply, regardless of what kind of heat source that you have. The electric burner is heating the metal, and the metal is heating the coffee. The electric burner is heating the air, and the air is heating the coffee.So it’s just all a matter of that particular system seeing how the coffee reacts within that system. And if you have electric, or if you have gas, or if you’re roasting on an air roaster,it’s about setting base parameters to start, with your batch size, temperature of your equipment, and the temperature of the coffee going in,and then how much gas or how many amps you’re going to apply to that coffee after that.

<Dave> Very good.Nick, anything else?

<Nick> I think we touched on this – Jeff is wondering moisture content of the bean or humidity -how much does that affect your initial charge temp or your turnaround point?

<Dave> Joe, every day up here particularly, humidity will shift on us. It Will go from a very humid day to all ofa sudden it’s dry.What kind of change do you see in the same bean that you’ve roasted on a Tuesday Versus a Wednesday.

<Joe> So this is a very difficult question to address.There is the humidity of the coffee itself – which I don’t know if that’s the exact question. I think that’s what the question’s applying to?

<Nick> That was the question, but i like both of them.

<Joe> Okay. And then there’s the humidity of the air that we are in, or the environment.In my opinion,humidity is not what is making any kind of an effect on any of this. In my opinion, it is the density of the coffee and the density of the air. The density of the air is kind of affected by humidity.The density of the coffee is also kind of affected by the humidity of the coffee.However, we can measure both through the density check on the coffee and barometric pressure within our environment.So, if you’re roasting on a small roaster like this,barometric pressure is going to be kind of a non-issue, and I think that it’s something that we really shouldn’t be focusing on. If you’re roasting in a very large roaster, the pressure pushing down on that roast is going to have a major change to how that roaster will roast. And so that in a large roast setting will affect the way that you play with airflow, okay?But I don’t think that that applies to 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 the moisture in the air,I would recommend looking at some other triangulating data to make sure that you’re not making a corollary judgment as opposed to an actual sound judgment.I think that baristas do this all the time. 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.” That Is a correlation,that’s not a causation. We know now that that is not true.

<Dave> So when you were a barista, you never said that?

<Joe> I did say that! And I said the samething about humidity and coffee and the same thing about humidity in the air but now I know better.

<Dave> Super!

<Joe> Now that I have tried like check your barometric pressure, check humidity,check the temperature, check the temperature of the drum, make sure that there’s not some other thing that is also off. And I’ll venture to bet that there is – that there’s something else that you can draw conclusions from.

<Dave>Good questions, Nick. Are there any others out there?

<Nick> No, we’re just all talking now about how you guys are amazing.

<Dave? Well, that’s good. That’s good. Good Session. Nick, I think we’re about at a wrap-up time. We’ve billed these as 25 to

<Nick> 34:00.

<Dave> Okay, what I’d like to do then is see if I can wrap it up –

<Joe? Do it.

<Dave> – with some…

<Joe> Are you going to actually rap?

<Dave> I’d like to… let’s see if we can summarize some of the things Joe Emphasized. Stay consistent on your charge size as you’re beginning to learn that roaster. Do the same charge size time after time after time. A lot of roasters,With the North roasters,do your full charge size.

<Joe> And make sure that that charge size is on the high end.Like we don’t wanna, if you’re on a one-kilo machine you say, “Well I’m doing the same charge size every time,” and you’re doing a hundred grams,that doesn’t count to us. Okay? You’re Too small, and the variables involved there are throwing you way off.Sorry to interrupt.

<Dave> No, I will permit that interruption a thousand times! The emails and the calls I get about that.What Joe discussed today, he was talking and using software profiling.Everything we talked about,if you’ve got a five by eight card with time and temperature and are tracking and plotting at that way, everything applies. Turning point is a variable that’s dependent on the bean, on your starting charge temp,and the ambient temperature in your atmosphere or whatever your bean temp is.Try to keep these consistent until you’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 a foot on the pedal. So pay attention to the sharp turning points.What else did you want to emphasize that I talked about today?

<Joe> The most important thing is, is it making you happy?Are you enjoying the coffee? That is the most important thing. Enjoying the process is great. It’s geeky,it’s fun, we can get down a lot of rabbit holes.But at the end of the day, taste your coffee, and if there’s something wrong,and you’ve done your homework to where you have managed everything,then you should be able to find that variable that was off. And if you don’t,that means that there are probably a lot of other variables that you don’t know about,so tune in to future events from us, and hopefully we’ll go over some of that.

<Dave> We look forward to that.

<Joe> Keep asking questions.

<Dave> Nick?

<Nick> I got two things for you, Dave.

<Dave> Yes?

<Nick> We need to see your tattoo.And I need you to drop this. Right in there. Made you a little paddock thing.Hold it up for the camera. Show them your tattoo.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…

<Dave> It’s a wrap.

<Nick> Peace!

<Joe> Dropping the mic!





Addicted to coffee at a young age, Nick has turned his caffeinated attention towards coffee roasting education. Behind the scenes, Nick produces, directs, and edits all video series for Mill City Roasters.