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 Roaster 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 a Deidrich 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 1 kilo drum, and I'm going to put in

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

collects 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

turn around 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 400,"

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, then 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 your 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.