Posted by Jimmy Evans

This video is the first part of our Roasting at Home Series where we are going to show you how to roast coffee at home. We will be looking into what you can use to roast your beans with from simple devices like breadmakers and popcorn machines up to more expensive options. Also, we will be teaching you many of the other intricacies and science involved in roasting coffee.

In this particular video we are roasting coffee on a modified breadmaker and we are going to show you how we track our progress throughout the roast process. We will be tracking the time as well as our temperature to create a graph and something we call a 'roast profile'. We use our roast profiles to either replicate roasts we are happy with or to make adjustments to improve on previous efforts.

We hope you enjoy the first video in this series and it helps you with your own roasting at home.

 

Video Transcript

Today we are talking about coffee roasting and particularly how you roast
your beans at home and how you can record the data so you can improve it or
repeat that process next time. In the commercial environment we have our laptops connected to our roaster and we get all this data that comes through
from the multiple different sensors that are in the roast and that's what we use
to either repeat a really great recipe or start to analyze the different sections of a
roast. If you don't have that information you're really just guessing.
So today you can see we've got a home roasting set up here. It's a bread maker
with a heat gun that's been converted to a roaster. We've got some green bean, we've got a multimeter which is going to measure just the temperature of those beans. We've got our trusty phone for a stopwatch and our cool Artisti roast
tracking graph. So i'll tell you how to get that one at the end of the video.
So what we're going to do is we're going to start and fill this out and take you
through the whole process.
All right so we're going to fill out our form to start with our green bean origin.
So this is a Colombian bean that we're using today and the farm estate, it's actually just a Popayan regional coffee and the process it's actually a washed. The crop year is 2021.
So it's good to have data of what you're actually doing so you can compare  these year in year out. Now the density of this bean we measured earlier which  is 723 grams. So density there's another video on that one which talks about how you can do it but how many grams per liter of water or volume essentially. Our charge weight is the amount of green bean that we're starting with when we pop in a roast. So we're using 300 grams inside the bread maker today and our
drop in temp is going to be an aim of 200 degrees. So i'm going to start this
onto dough mode and basically that means that the little propellers inside there are moving around the green bean. Just going to get some heat into there.
I'm going to aim for 200 degrees so when it gets to about 220 we'll pull the lid
off pop in the beans and we're going to have to start our timer and then we're going to record every minute from there, what the temperature reads
on this graph and there's a couple of different stages we're going to keep an eye on to then make sure we get the critical parts of the roast recorded to be able to analyze it at the end.
Okay so we're at 215 degrees. So 220 I'm going to start my timer. I'm going to drop in these beans. There we go so we need to record our drop in temperature and i've got that written in a space down here at the bottom. So 200 degrees and we're going to mark it on our graph as well at our zero point. Now we're keeping an eye on what happens with this temperature. We're waiting for those beans to take up the heat that has either been preheated or not being sucked in from the heat we're forcing on it now.
So it's going to be the lowest temperature that we're going to come up with so we've dropped down to down 99.1, 98, 97. It's starting to come down so this is where we're going to have a positive impact on the beans. Basically they're sucking up all the extra heat that's there. So we're down to 92, 93 and I'm coming up to a minute so i want to actually record that. So at 91.6, there he
goes right on it.  91.6 at one minute was our turning point.
So now we're going to keep an eye on how quickly these beans are actually heating up and if it starts to go up too quick we can start to reduce the heat. In the first part of the roast we're starting to dry that roast so generally you have a bit more heat and as you get towards the end of the roast you start to taper it off. But if it happens too quickly we want to reduce it.
So i'm just looking at this and within a minute we're going up quite quickly we're nearly going to be around the 20 odd, 25 seconds at a degrees per minute at the moment so i know that's already cranking along. So, i'm going to bring that right back to number two heat setting on the heat gun. So we're coming up to two minutes and our temp is 129.
There we go so let's put little dots on the graph and you can see even straight
away we had a lot of heat that that got onto those beans really quickly. I'm
just going to keep looking at this all the way through. So i want to slow that
down a little bit. That was definitely a very quick recovery. So next time I wouldn't leave it on three, i'd come back to two.
So right now those beans are moving around. We're getting not only some conductive heat from the actual metal on the actual base of the bread maker they're getting the convection from the blowed  fan forced heat from the heat gun too. You can see a little bit of smoke starting to come out there as well. It's still going pretty quick. So i'm going to go down to setting one on the heat gun there. 
I want to slow it right down a bit. So now we're sitting at 144. Just about to come up to three minutes. There we go three minutes 145 degrees. There we go,
so you can see now we definitely halved the rate of rise that we had from our
turning point up to our first minute. So now hopefully we're going to get a rate
of rise, I'm looking for around 10 to 11. If i can achieve it on here up to what we call the yellowing point or which is about 165 degrees normally on our  commercial roasts and that's where we have our end of dry. 
So basically we're just trying to take the moisture out of the beans. Up to this point, do it reasonably gradually. We don't want to go as quick as I was doing before because we want to maintain. Well I'm just having a quick look here
It's actually going down now so I'm  going to chuck a bit of extra heat in there to try and come back up. So that actually dropped back down to 140. 140 on the dot now and it's probably going to come back up, hopefully with extra heat.
So this is where you've got to make sure your heat is increasing and it's actually getting penetrated into those beans. They've sucked that up really quickly so
i'm just going to get a bit more heat in there.
Okay so now we're going back up again. So those beans just sucked up all that heat and that's basically the cell structure and the moisture coming out of the bean and that's what's basically absorbing all the heat. There we go so we're kicking back up again.
I missed the four minute mark there with a little challenge but let's say it
dropped down to I think 135 and at minute five we're coming up to 154.
There you go there's a bit of an example of exactly why we track it. The heat went up, dropped right down, we had to increase the heat again so not as scientific as the roaster behind us but hey it's a bit of fun. It's going to give us a better quality roast when you've got something at home.
So, coming up to five and a half minutes. It's at 168 so that's at five and a half minutes. That is our turning point um, that is our end dry. So just writing that 5.5 minutes. Now basically that's the end of the dry which is the starting point of our
mailiard and sort of development of caramelizing sugars and reducing our acids in the coffee roast. So this time right up to first crack is the malliard reaction  that's going to happen.
So we'll wait and see how much we can stretch that out. I want to try and slow
that down a little bit. It's definitely pumping along. Six minutes just went by there while i was yakking away but we've missed it. So at 6 minutes 30 we're 194 degrees. So we're cranking along really fast at the moment. I'm going to reduce that heat right back and try and taper it off. This is going to be quite a quick fast roast for 300 grammer in this little bread maker. 
There we go I'm actually starting to hear a bit of a bit of a crack starting on a couple of those beans so it's 196 degrees. It's actually losing a bit of heat at
the moment tapering right off. So i do need to add more heat there. So you get the first crack when one or two beans start to actually pop but you want a rolling crack where it's really constantly starting to to crack away on a lot of those beans in the batch. So when those first cracks happen that's actually absorbed a lot of heat, like so much heat. Seven and a half, it's actually down to 189
coming into the eight minute mark. We're at 188 so we're actually reducing
temperature a lot there. So if you weren't monitoring the heat gun right now you wouldn't know that these temperatures are going up and down and the beans are getting heat and then they're not getting heat. That's basically how you're changing the caramelisation and the acids in the sugars so you want to be very constant and be able to control that. 
So as much these figures are all over the place right now it's good that we know what's happening otherwise we just think it's going perfect and it was roasting  nice. So we are getting a nice solid crack coming through now you might be able to pick that up in the in the audio. We're coming right back up now to 200 degrees. Se're at nine minutes and i would say that's first crack right now for sure at 202. This first crack and you can really hear that pumping along a bit of smoke coming out now as well. i'm going to reduce the heat off because I really want to slow this right down and just coast it along from here. 
So we're now into the development stage of the roast. So this is how dark you're
going to make your coffee. Is it going to be a light filter roast a cinnamon or
a full city perhaps? That's what we roast a lot of our blends at. We're just at 216 degrees and it's really starting to get that rate of rise. Really slow ideally if we can be around three to five degrees rate of rise per minute right here it would be ideal.
So we're coming up to 10 minutes. it's right now at 218. Yep great so 218
at 10 minutes which is great. You can't see the beans, quick little sneak peek their. They're looking really good i don't want to go too dark on here. I'm going to go another one minute. I don't want to burn the beans and i think that's going to be perfect for us. So how do you deal with these,a bin lid or if you had a colander or something like that. Get yourself a fan as well. This part's a little bit messy i'll be honest. So 222 at 10 40 for us is going to be my mark. 223 awesome! So i'm going to remove the heat, take off the lid, turn it off, pull out our heat probe. There we go. Turn on our fan.
There you have it some roasted beans. You've got to cool these down as quick as you can. Now i don't have a colander but that's definitely a better way to do it. These are still cooking away so the quicker you can get this cool the better it's going to be. Now if you come in close you can have a look at how awesome this roast is. There you go from a bread maker that is pretty damn awesome!
There you go so i'm gonna let that cool away. Now we probably won't drink these but we'll let them cool. I might spread them out just a little bit. There's still
plenty of heat left in there. I'm going to come back and have a look at our chart. So we've now got to the stage where we can really analyze what has happened.
So at our end time, I believe was about 11 minutes 40 i think it was. 
So i want to make a note of that that which is our total roast time. Now we can draw on here our graph but there are a couple of key points. So we've got our end roast. We've got our drying point at 165 degrees and we noted down at 202
being our first crack. So this is our 202 here. That is our first crack. That's our
our dry. So we've got a little spot down the bottom here where we can do a few calculations. Now i'm just going to draw this in a line so you can sort of see what
happened with our roast. So we started up nice and high, we got down to our turning point. That's when we had a positive impact on the beans. I started to lose track of what was happening with the roast and they absorbed a lot of heat. It went sharply down. We had a huge loss in rate of rise really quickly but then i put the heat back on and you can see it just started to climb nicely and then around just before crack we lost heat. So the beans really absorbed any of that latent heat or basically the energy we had that was rolling along we lost that so it did drop down just before first crack and then we recovered back up to first crack at 202 degrees. So they that is the other section in time that we are going to measure and from there right up to when we finished our roast. So down the bottom here you can see that we've got our dry, our time, our percent of the mailiard phase, the time percent development and the time and the percent. 
So what we're going to do is we're going to use our 11 minutes 40. We're going  to grab ourselves our calculator here and we're just going to work out how much time is from each segment the three different stages of the roast. So we've said at 165 degrees it's 5 minutes 50. So for our dry our time is 5 minutes 50 and 5.5 divide that back into 11.4 is 48.2 percent of the roast is our drying stage.
Then from our dry stage to our first crack in time. Our first crack happened it looked like uh nine, just over nine minutes. Probably nine let's call it 9.20. I  missed that one on there i'm sorry so if we go 9.20 that is. So you go yeah
um 11.4 minus, minus your 5.5. No sorry 9.20. Get the math right here Luke! Minus 5.5 equals 3.7. So we've got three minutes 3.7 minutes and then you divide that back into your 11.4 which gives us 32.4 percent of the roast is our mailiard phase which is the caramelizing sugars and getting rid of the acids. That's a key part of flavor that you really want to concentrate on.
So then we have the balance up to 11.4. So if we go our total roast time 11.4
minus our 9.2 we're at 2.2 minutes and if we take 2.2 and divide that back
into our 11.4 we're at 19.29 percent of roast development.
So there you go guys they are the three phases. I hope that maths is right. I'm
pretty sure i'm right with the calculator there. Tell me if i was wrong but that now gives us a guideline to see what stages of the roast we want to change. We've got a bit of an issue there which happened in the dry. We went really high then we lost some heat. That happened  just before first crack as well and the development at the end was probably a bit too quick. We basically developed the coffee in two minutes. Now you could go back and analyze these at every
individual minute and have the difference between the temperatures from the start of a minute to an end of a minute and that is how you get your rate of rise.
So I hope that's helped you guys. This is going to be a downloadable pdf which we'll chuck a link down the bottom for you there and i hope that's going to help you assess how you roast coffee at home. I'd love to hear your feedback, tell us
how you're going. Tell us your successes, tell us your failures, it'd be awesome to know what you're doing different at home.
Thanks very much for watching guys I hope you've enjoyed this and it's going
to help you roast we'll catch you next time cheers.

 

 

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