Roaster School Online – Ep #2 – Drying/Yellowing


Roaster School Online – Ep #2 – Drying/Yellowing

Hello everybody Joe Marrocco here from Cafe Imports broadcasting from
Mill City Roasters in Minneapolis, Minnesota and as you can see I’m all
by myself today my co-host Dave Borton unfortunately is
at home. Fortunately with a new knee and
hopefully he’s got that knee propped up high with a nice beverage with a little
umbrella in it or something like –well maybe not because he’s probably on some pain medication so maybe stick to the ice ice coffee, Dave and we’ll see you next month but for now you all are stuck with just me so it may
get a little bit bipolar, I may start talking, you know asking myself some
questions and going back and forth we’ll see how this pans out. Today I have
a second part to the study that we’ve been going into on the profile on the
curve as you can see and I’ve already done some artistic rendering so i hope you
enjoy the art throughout today’s program. I’m starting to consider myself–oh
what’s his name? Nick, you might have to help me the
painter my happy little, my happy little, profile right hereBob Ross. I’m the Bob Ross of coffee so I
hope you all enjoy that. So today we’re going to talk about the
drying stage. Last month we talked about the
turnaround or turning point, as they like to call it in these parts of the world and so today we’re going to talk about what happens between this turning point and when the coffee actually starts to
change in color. We’re going to talk about not only what
is physically happening to the coffee itself, but also how you should respond
to its happening with the coffee and how you can decide whether or not what’s
happening with the coffee is correct or incorrect. And I do want to give that
disclaimer that on each roaster it’s going to be different, so
especially as you are getting deeper into the roast you may have a turning point that is
going to be similar from one roaster to another roaster. However, once you start moving past that point our roaster begins to
separate: one roaster will go one direction another roaster will go another direction. Ok. And I also want to say that we are
specifically talking generally on these shows about a drum roaster, not
necessarily your air roasters or fluid bed roasters although the science is
still the same as far as what is happening during yellow. So here you have the turning point, just
in review if you did not get to watch last month’s
maybe go ahead and pause this, watch last months and then come back to this. But
I’ll quickly review a couple of things. The turning point itself is actually a
myth. It’s a make-believe point of where we
see coffee go from hot to then moving back up because this is
actually not what’s actually happening. What’s
happening is coffee is down here, the drum is up here, and the probe has
been steadily reading the temperature of the drum and now we’ve added coffee so as coffee is pulling against what the
probe is reading it takes a little while for the drum in the coffee to reach a
point of equilibrium. And that’s really what this is showing–so the coffee is
not turning around, the coffee has been steadily increasing in its temperature
since the moment that we introduced it to the drum Ok. As coffee is absorbing heat, that heat,
which is energy, is going to start changing the state of the coffee. The first indication of change is color. When it comes to our eyes, visually we will see the color of the
coffee change, and we’ll also smell the aroma of the coffee changing. Now a lot
of people will start getting very carried away during this stage with
looking at instruments. You’ll look at that that temperature probe and you’ll get
drawn into that temperature probe and I want to tell you you’ve got to stay in
tune with the coffee. That doesn’t mean just sit there and
keep trying and trying and trying and trying that means that you need to balance
trying the coffee, smelling the aroma, looking at the color, look at the timer,
look at your temperature, and make sure that all of these indications are in
tune. Ok, so what’s happening with the coffee here? So we have a seed and that
seed has has a particular amount of compounds within it. Those compounds are drawing in heat. Now physicists tell us that things that are
dense absorb energy more quickly. Things that are less dense absorb energy more
slowly. So like for instance, right now I’m in a
room if I’m cold in this room I can put a heater in the room. If i put
the heater in the corner of the room, it’s going to take a long time for that
heat to move its way over to where I’m standing because this room is not very dense. Now
if i fill this room with water and I put a heater in the corner of the room that
heat is going to move more quickly through the water because water is far
more dense. Now, if this room–now of course i
couldn’t survive in this scenario–but, if this room were nothing but metal and I
put a heating element in the corner the heat would move through this room
very quickly because metal is a conductor. When you have something that
is dense it generally will conduct energy. Ok, so a very dense coffee wants to
conduct energy very quickly. Now you may be saying to yourself, “but
wait, I thought that you’ve always said that are more dense coffee needs more
time to absorb energy?” This is true. Since that dense coffee
wants to absorb energy very quickly, during that process the outside part of
that coffee will want to change due to energy being absorbed at a much more
quick pace than the interior of the coffee. So for a more dense coffee, we want to
have the time during this stage to kind of slow down. Ok, so let’s put on the board a coffee
seed. I’m going to get rid of some of this
stuff, ok. Here’s your coffee seed. All right. Now this coffee seed, let’s say
it’s very dense, has these very tightly packed cells. On a very dense coffee
energy will start to move in and what happens now is that moisture will start
to move out off of the coffee. And as that’s happening there is a cooling that
will start taking place on the surface of the coffee. During that initial stage
of heat being absorbed into the coffee you were still losing moisture through
the act of evaporation, and that evaporative movement will cool the
outside of the coffee and then you will protect the inside of the coffee from
that heat. Soeven though density will absorb heat
more quickly that reaction to that heat that it absorbs will also happen more
quickly so we want to space that out. Ok, so for more dense coffee as you come
around that that turning point, we want to make sure that that turning
point then results in a little bit of a slope to the curve, a little bit less
speed coming out of that turning point for more dense coffee. A less dense
coffee is not going to have the absorbent ability that a higher dense
coffee will have and so we have to enforce some more energy onto that
coffee in order to get it to start moving. So for a less dense coffee we can have a
tighter and sharper turn. Now, a lot of people want a very clear-cut answer as
to how fast their rate of rise should be from the time that you have turn around
until the time that you see yellow. There’s no cut and dry answer. I will say
I like to measure every 30 seconds. I like thirty-second increments because if you have a roast that’s only
10 minutes long and you’re only measuring every minute, from the time
that you reach yellow to the time that you’re done, you’re really only getting
about three to four, maybe five measurements. Whereas 30 seconds doubles that. So 30
second increment, I really like to see somewhere in the
neighborhood between 14 and 18 degrees per 30 seconds. But, again that is really going to depend
on your roaster, on your instrument, on your coffee and all of that. If you’re roasting in a sample roaster, a
very small roaster, you may see that that number is very
high or you may see that that number is very low. Usually on the smaller equipment we see
a larger divided on how their probes are reading. Ok, so what is happening physically to
that coffee right now is what we call an endothermic reaction. The ability for the coffee to absorb
energy, or the state of absorbing that energy. While the coffee is absorbing
that energy however there is still reactions that are taking place. The reactions that are taking place at
this point are not chemical reactions, where you have molecules that are
breaking down, they are more physical reaction that’s taking place. The physical moisture that is in the
coffee is beginning to leave that coffee. It’s beginning to be evaporated off the
coffee. Don’t be confused with boiling point of water, ok, because we’re still not quite going
to be at the boiling point of water. This is more of a drying action–so a lot
of people call this to drying phase or the drying stage and that is that endothermic reaction that is forcing the
water to evaporate out of the coffee and then getting the compounds that are in
the coffee ready for chemical reactions are what we would call XO thermic
reactions or the release of energy through change brought on by heat. Ok, I hope that is very clear. So as we
move it actually starts way down here with the coffee because, once again, this
does not exist. So, as you’re moving from the temperature
that you put the coffee into the drum at, room temperature let’s say 72 degrees, as
you’re moving through the coffee is actually doing this. When you get to that
stage where you see yellow, now you can know that that coffee
has dried to the point where it’s ready for chemical reactions to start taking
place. Ok, you’ll smell the difference in the
coffee. So, as you put the coffee in it will
smell like green coffee. If you want to know what green coffee smells like when
you open that green coffee bag and you smell that aroma that’s what I’m talking
about. It smells grassy, it smells kind of like
green peppers sometimes it has a muskiness to
it. That aroma will change to being more like hay or straw or oats, something of
that nature. Nowif you think about that in a botanical sense if you make a
correlation to other grains or grasses, which coffee is not a greener grass, given, but it responds just like one. If you make a correlation to that and
you smell grass and as grass gets cut, which were doing to the chlorophyll
that’s in that green coffee seed, as we begin to heat it, as it gets cut you
really start smelling that aroma. So as you get past turn around and start
heating that coffee, that green coffee aroma will in intensify and then we’ll
change. It will change to being like dried grass, which is your straw your hay
your oats your wheat things like that it’s just dried grass. Now you’re getting down to the
carbohydrates, then later you’re going to change as you move further through your
browning reactions. So this stage is all about preparation.
Ok, there’s been a lot of study that’s gone
into this stage and one of the coolest parts of the research that
I’ve seen is that for if you have one single seed and
you’re in a lab scenario to where you can inflict upon the seed a curve that you
want at any point, so for instance you could hold the
seated at a yellow for an hour and then all of a sudden jump that curve up
because you can inflict heat on it that way. Well, they found that the amount of time
that it takes from green to yellow has no determinable result on
flavor. It does not affect the flavor of the
coffee because at this stage you’re not going through any kind of
change as far as the chemistry of the coffee is concerned that will result in
a flavor change. However in our drum we are preparing that coffee for those
changes. So, as we nearer to those browning
reactions, if we’re moving into browning at a very fast speed then we can move
through browning without achieving all of the reactions that we want. If we move
through browning at a very slow speed, then we will not be able to break down
the coffee to have all of the reactions that we want. So we need to move into browning at a
speed that equivocates to a browning reaction that takes the amount of time
that we needed to take. So this is preparation–everything
leading up two yellow is preparing the coffee to move through the browning
stage. So you want to see that generally in
about four to six minutes on most drums if you’re moving much slower than that,
then as you approach browning you’re not going to have the energy to get those
reactions. If you move too quickly then you’re going to move through browning so
quickly that you’re going to have some singeing to the coffee, some scorching to
the coffee. Coffee scorching will also occur during this time. If you see little spots of darkening on
the outside of your coffee as it turns yellow, those spots are scorches. If
you’re seeing browning on the coffee during the endothermic stage, where that
browning is happening is no longer endothermic. Now it’s starting to have an
exothermic reaction on that spot. That exothermic reaction will then
continue as you move through the roast and it will over roast on that part of
the seed. Once you start seeing that you really
cannot reverse it. So at that point that coffee is going to, you know it’s going to have charry flavor to
it. I think that’s a good start to this conversation. Nick, do we have any questions?We had a question earlier that you started to touch on, I’m just gonna ask the question so that we get a nice sound bite for the new segment. What aromas should they be smelling from the start to the end of this phase?So,what aromas should you be smelling?
You should be smelling grassiness, green pepperness, those green chlorophyll-filled aromas to breadiness, the aromas of carbohydrates: pancake, waffles,
biscuits, wheat, those kinds of things.Joe, would you be interested in doing a larger
format Q&A session to let these guys just spew you stuff at you? At some point?Sure, I have the question
of would I be willing to do some kind of a Q&A. I’m absolutely willing to do a Q&A.And the next thing is, and I know the answer to this but I’m hoping you can expand on this a little bit more: Why can’t we fix someone’s roast when
they send us a profile?So the question is why can’t we fix someone’s roast when they send us a profile I would say that there are a lot of layers to that question. It’s kind of like, let me let me come up
with a good analogy for this. While my brain is working on the analogy,
I want to talk about the physical ability of our machines. So all of our machines are
different. Your probe is going to be different than somebody else’s probe,
even if you have the same probe, even if those probes are calibrated, the metal
around the drum is going to allow for a different amount of ambient temperature
to hit your probe, the beans going into your drum may be at a different ratio,
may be at a different temperature going into the drum. There are so many factors involved,
that’s why we have to go back to paying attention to the coffee. What is the physical coffee doing? And
then retro fixing your curve. Ok- to what the coffee is doing. So if your
probe is reading one number, like for instance if I tell you that
yellowing happens at six minutes at 300 degrees Fahrenheit, and you go to your
roaster and you get to 300 degrees Fahrenheit in six minutes and you’re at brown and you come to me and say your profile is wrong, I’ll say, “no, my profile is right, you
should have slowed down your roast. Your temperature is different than my
temperature. So we can’t really just look at the numbers and figure it out. I can’t teach somebody how to paint with
a color by number chart. The only way that I can teach somebody to paint–
well I can’t teach someone to paint it all– but the only way that I could teach somebody to paint is through helping them see how adding this color will cause the
effect of seeing how that color corresponds with another color in those
things coming together now start painting a portrait. And then you have to go and
actually practice. You actually have to have the the physical ability and the
interaction with the medium in order to adjust yourself to that medium and then
start to artistically express yourself. So, coffee is artistically expressing
yourself. Now we have science that we can go back on, but our tools for measuring
that science are going to be different. So, if you are able to send you know–
parts of your roast all the way through your roast along with the profile of
your roast then that could start narrowing in on how somebody may be able
to help you, because then they can smell and say, “oh wow, at yellow your
scorching,” even though you say this is 300 degrees at six minutes. It’s still
moved too quickly for this particular drum. We have to taste it and see it.Ding! Send some coffee with your profile. We’ll all appreciate it. Mike is wondering, if your aromas in
drying always follow the same order? That’s very sensory, that’s very
perspective of the individual roaster, and what he can smell out of it. Your experience? Do you find that the
different stages in drying of yellowing phase follow the same aroma kind of curve with the temperature?This is a really good question, and
interesting question: does the aroma of coffee always change in the same general
direction? Yes, yes it does. Once you have gotten all
of the chlorophyll out of the coffee, once you have achieved drying that
coffee, it will not then smell like grass. Once
you get past that wheaty stage, that really hay-like stage and start moving deeper
into bread, and then into baked bread, and then like darker baked bread,
and then into cookies, and other things we’ll talk about in the future, you won’t
go back to just smelling that straw. Ok, because what’s happening is that
molecule is now gone and now it’s different molecules, and then those
molecules are gone, and then they’re different molecules.
So you’re changing the coffee in a chain. So, the further you get down that chain,
the more you’re going to not be able to go back. Ok. The maillard reaction, carmelization, you cannot undo what you’ve already done. And, the same is true for the very initial
reaction. Even if you were to soak that coffee
in water, you’re not going to get chlorophyll back into that coffee. Ok–Cool. Any other questions for us?We have escaped from the guantlet of questions.Ok, so we have no other questions coming
in, I did want to make another point that i’m going to try to recall. One thing
that I was talking to Steve about, here at Mill City, is a lot of people are
calling in about their temperature probe profile, or their profile software has got a lot of noise
in it. You’ll see like a zigging line that’ll occur, especially you
know, it’ll be like really intensely seen on your rate of rise. And so people get
really caught up in looking at that crazy, you know, zigzag motion when really that’s again
why you need to go back to the coffee. Those lines are there to help you,
they’re there to go back to later and try to repeat a similar roast profile. But
just because you have a lot of noise through the electronic equipment doesn’t
mean that you’re ruining your roast, or that you’re going to be able to taste
that in your in your end product. All of these roasts are going to be kind
of on a bell curve like, i’ll say over and over, of acceptability and even
though your profile may have little zigzags, it’s still going to be in a
situation on that bell curve to where you’re not going to be able to taste the
difference if your rate of rise is you know a couple of degrees different on
this little zigzag pattern. Ok, so take yourself out of your
profile material and try to stay with the coffee as much as you can. When you
start getting with the coffee too much take yourself out of the coffee and put
yourself into the profile material. Until you can start using them in a really
natural way, to where you flow and you’re comfortable with them and then at that
point try a new coffee and just continue to
grow, continue to build, and continue to look for things that make your coffee
tastes good. If you are exchanging those profiles
with each other, there’s going to be a lot of
peer pressure for your profile to look polished. And while trying to polish your profile,
you’re going to lose sight of what you’re actually doing which is roasting
coffee. What you’re doing is cooking coffee,
you’re cooking coffee. Don’t try to dress your profile to
impress, try to dress your cook coffee in a way that actually tastes good to you, represents where the coffee came from,
etc. That’s not coming at you as a reprimand but as an encouragement, and
hopefully liberating you a little bit from worrying about that profile. Ok, another thing that I wanted to talk
to you about is once your coffee does begin to reach that boiling point, where
water is going to start boiling out, that is going to be where you’ll see that
coffee dry out. And the drying of that coffee is actually, and I’m gonna erase this
whole thing. Your coffee is going to start at about,
let’s say well– I don’t know the quality of coffee that you’re getting it could
be very different, so we’ll just say 9.5% moisture to 14% moisture somewhere in that range is
where coffee is. We really really really like to see coffee at 10.5%
moisture to 11.5% moisture. I’m going to go down a little bit of a
rabbit trail here in a moment, if we have time, as your drying that
coffee out this moisture drops, ok, this moisture drops to about 0.5%
moisture to 1.5% moisture. Ok, during the rest of the stages of
roasting your percentage of moisture is going to reside around this number. Generally closer to this number as you
get later into your roast. Ok, so this is about where coffee is going to be at its
final roasted product and the reason for this is as you start breaking those
molecular chains down, even though this 0.5% is still evacuating
your coffee you’re creating new moisture that’s
going to replace that by breaking down your molecules. They’ll break off H2O molecules off of larger
carbohydrates and other such molecules. Ok, so you’re you’re releasing moisture
but you’re also replacing that moisture and so you reach the status, this like– what’s the word I’m looking
for– homeostasis almost in the state of where
your moisture lies because every time you really some you’re creating more, so you get kind of a cycle there. Ok,
now this is my rabbit trail. Ok, are you ready? This number, this
initial number– and this is, you know, something that is
very controversial among a lot of roasters– this number does not matter this is not
discussing density. Ok, this number does not matter as to how
you apply heat to your coffee. Ok, if you’re reading 14%
don’t say, “well, then i need to roast it in this way.” If you’re reading 9.5% don’t say, “well, then i need to roast that in this way.” Ok, because those those things are
percentages of moisture in relationship to density of the coffee and the density
of the coffee’s what you really need to look at. The density of the coffee in
correspondence with the moisture of the coffee, and in correspondence with the
size of the coffee will tell you how your coffee seed is going to absorb
energy. Whether or not it’s going to absorb very quickly– too quickly or too
slowly and how you can apply energy from there. I hope that is clear, I know I harp on
that a lot. One of these days maybe I’ll write a
really good concise article on all of that we’ll see if I have the time.Somebody asked you to draw more beans, just thought you could show us all a quick–Oh yeah so my friend–It’s like a perfect math circle for coffee beans.My friend Ian Pico
down at Tulsa, at Topeka Coffee, drew this lovely coffee seed and I’ve
been practicing it ever since. It’s kind of something like that–that
looks more like a tongue or a butt–let me try that again. Ok, so he just kind of comes around and
then makes a little curve that–A wave?Yep, the little wave, the reverse wave. So I’ve adopted that into my repertoire of artistic abilities, thank you Ian. Any other questions?How is the density of a bean measured? Oh we have a video that.Mass over volume. Get
yourself a pipette, fill that pipette to a certain level with all of the
different coffees that you have–Not together.Not together, separately and
then weigh that out. If you fill it up to 200 milliliters and it weighs ‘x’ grams,
and then you fill another one up and it’s ‘x+1’ grams, then you know the ‘x+1’ is more dense than the ‘x’ grams.Do you remember which video that’s in?I don’t–Perfect.I’ll do something, actually let me–You want to draw it?I’m going to draw something, how much more time do we have?We have as much time as you want.Ok, lets get into this a little bit. This may be worth all all of your money
that you paid for the show. Ok, so give me a second i’m going to turn
my back to the camera and draw a couple things. You’re welcome. Ok. Ok, this way is…Steve’s probably at his desk watching us
right now just like, shaking his head.Ok, you have 2 pipettes. We are going to get hypothetical here
and say these pipettes are both 200 milligrams and they’re both filled
with coffee. To 200 milligrams. Ok, hopefully you are with me so far. This
pipette weighs 100 grams. Ok, this pipette weighs 125 grams. So, mass
over volume is going to give you your density. Density equals mass over volume. Ok, so I’ve done this so that it’s very
easy for you to see. Now, which one you– don’t have to answer
because I won’t hear you– of these is more dense? You’re right, this one. I heard you. This one is more dense than this one, ok?
Now let’s pretend together, shall we, that each one of these grams is actually
one seed. Ok, so if each one of these grams
represents one seed, which it would not in real life would be closer to seven to
ten, but if each one of these seeds
represents one gram, or each one of these grams represents one seed then
this pipette would be filled with 100 seeds. Following? That would mean that for the same amount
of space there would be 100 seeds filling this, but each seed would have to
weigh 1.25 grams. 1.25 grams, ok, so 25% more than the
sister seed over here. Now, what if I then took a moisture
measurement on these two coffees and both of these coffees read 10%. Let me put that in a different place. What if both of these are 10%
moisture? Now, if i measure of just moisture and I
go off of that then i’m going to assume that i’m going to need to roast both of
these coffees the same way. But, I don’t need to assume that because I’ve
measured the density of the coffee, ok, and the density of the coffee tells
me that these are different. Now, moisture can be a component of density. Ok, so i’m not saying that the moisture
within the coffee is irrelevant but i’m saying it’s only partly relevant. It’s
part of a whole picture and the whole picture can be seen much more clearly
when we have mass over volume, when we have that density reading. Ok, if you have a really nice density
meter generally there should be some kind of
component, if it has a volumetric component which a lot of them will have
a tube that comes with it, that volumetric component can be used to give
you a density reading which is usually bushels over pounds or something like
that so that you can start charting your density on your coffees as well as your
moisture in your coffee. So now, if this is 10% and this
says 10%, we know that this one by nature of being more dense, 10% of 125 is more than 10% of 100 grams. So I know that here I have 12.5 grams of water and here I have 10 grams of water. So even though my percentage is reading
the same, my percentage then I can use mathematically do some algebra and you
can look at exactly how much water you have in that particular coffee. Ok. So that’s why the percentage of
moisture can be very misleading. Ok. Furthermore, furthermore, as you are
going through yellow and this is where we’re coming back to reality here for
our drying stage. As you’re coming back through yellow, pretend like this is our
graph, remember it falsely has the turnaround, as you’re coming through
yellow whether or not you have 12.5 grams or 10 grams you’re going to drop down to about 0.5% to
1.5% moisture during that stage. You’re going to dry out enough, hopefully if you go through the stage correctly and then start moving through your browning
reactions correctly enough to where this moisture is going to be out of the
way. If this moisture is present you cannot have a browning reaction, ok?
Browning reactions, by definition, are dehydrating reactions. That is when your molecules are losing H20 components off of the molecule and your molecules are breaking down. So, if there is H20 present at that time
you cannot have the maillard reaction and you cannot have carmelization, ok? So that’s
why drying is so important. We need to get that moisture out of the way, use the moisture while it’s there to
pull energy into the seed. Once that energy is there we release the moisture,
we have more airflow, and we can move through the next reactions, which–come
back next month and we’ll talk about those. Any questions? I’m sure we’ve
sparked some more.Milliliters. Not milligrams.Milligrams…exactly, this should be milliliters. So sorry.That one’s for you, Rob. There ya go.And just a point of clarification:
milligrams and milliliters are virtually the same with water, but with coffee obviously coffee is a lot less dense than water so you’ll have a lot fewer grams per milliliter with something less dense than water. But yes, sorry about the milligrams. I don’t know what I’m thinking.We often don’t either, bud. Anybody else have anything else? Now we have to wait for the delay.It’s okay. We’re gonna hang out for a second and wait
for the delay. This is gonna be awkward because you will have already been
through the delay by the time you hear me talking about the delay. But it should
pay off in case we have any other questions.It’s only gonna be like another five seconds. Youtubes. What we give them 20 seconds to type?Yeah.It should be like right around now. And we’re calling it!All right–that’t it.Roaster’s School, Episode 2.Episode 2 of Roaster School is out.
Please hit us with your questions for Episode 3 which is going to be on your browning reactions, as we’re moving from yellow to first crack. I’m not quite sure where the first crack
is going to get its own episode or whether that’s going to be included in
next week we’ll just see how next week goes. Thank you, please come again. Get better,
Dave.Bye Dave!

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32 thoughts on “Roaster School Online – Ep #2 – Drying/Yellowing”

  1. Jorge Salazar says:

    The seasoning greens that you all recommend for practice, where do these greens fall into as far as density? Would scorching occur when the beans are left in the drum for 20 minutes during the seasoning phase. And can having the drum speed to slow cause scorching? Thanks.

  2. Paul Walden says:

    Just want to say thank you guys for all of the awesome information. We are very happy we stumbled across your videos, you are a blessing!

  3. Christopher Ptacek says:

    The Minnesota Metric System has me bewildered! However, I can't thank you enough for taking the time to make these videos.

    How important is it (opinion) for a small commercial roaster (like Mill City customers) to be tracking density/moisture in their roast process?

    What tools does one ideally procure for this, apart from scales and graduated cylinders? Thanks again! Happy Cafe Imports customer, btw!

  4. joshd says:

    Just for additional info for new watchers that might got confused with the first graph. He actually wrongly put the time and temperature on the graph, it should be switch. So you will get temperature for the vertical line and time for the horizontal line. Hope it helps!

  5. Benjamin Kruger says:

    Great videos! I was surprised to hear my local roaster mentioned. I absolutely love Topeca's "seed-to-cup" Ayutupeque, El Salvador.

  6. James Ward says:

    I agree with the comments below, these videos are so valuable to so many people for so many different reasons. Ive seen pretty much every video on this channel and it has helped me so much to better the finish on all of my roasts. Thanks again for everything. I and rarely ever leave comments, so that alone tells you how much I am thankful for these videos. Keep it up.

  7. andres padilla says:

    thanks for the videos, very useful!
    just one thing, milligrams is a measure of mass not volume, maybe Joe was thinking on milliliters

  8. Yousg27 says:

    thanks man. really nice

  9. aldy antonius says:

    Hi i would to ask about if the denser beans have 12,5 gram water so it's mean we have use a higher gas while drying ? Than the lower dense ?


  10. roberto muhammad says:

    hi Mr john morocco and all north roaster expert . is all these stages and standards important to apply it in AL kind of coffee or just espresso or American coffee ( is it important for Turkish coffee roasting too ) ? and whats the starter flame ( burner ) level i should select if i am new roaster in order to reach yellow stage within 6 mins ?

  11. Alex Levitt says:

    joe says "the density of the coffee in correspondence with the moisture of the coffee and the size of the coffee will tell you how your coffee seed is going to absorb energy". i am a still confused on how this works…

    i'll try to pose my question using the example joe used in the video where you have two 200 mL graduated cylinders and you fill them to the brim with two different coffees with equal moisture content (10%). coffee A (ethiopian heirloom) has a total mass of 125 g and coffee B (marogogipe) has a total mass of 100g, such that the density of ethiopian heirloom is 600 g/L and the density of maragogipe is 500 g/L. coffee A consists of ethiopian heirloom varietals so its graduated cylinder contains 200 beans. coffee B is a maragogipe, which is larger in size, so its graduated cylinder only contains 100 beans. this means that ethiopian heirlooms weigh (on average) 0.625 g/bean whereas maragogipe beans weigh (on average) 1 g/bean.

    to me, this means that you'd have to apply more energy to to take the moisture content down from 10% -> 1% for maragogipe bean (10% of 1 g / bean = 0.1g water/ bean -> 0.01g water/bean = 0.09g water loss) and less energy for each ethiopian heirloom bean (10% of 0.625 g /bean = 0.0625 g water / bean-> 0.00625 g = 0.05625 g water loss).

    HOWEVER, I would think you'd need to apply the same amount of energy to take the moisture content down from 10% -> 1% for 50 g of marogogipe beans as well as 50 g of ethiopian heirloom beans (10% of 50 g = 5 g -> 0.5 g = 4.5 g water loss). [I've only roasted 50g samples with an Ikawa roaster.]

    Does it matter that this 4.5 g water loss would be taking place in 50 marogogipe beans ( 0.09 g water loss / bean) versus 80 ethiopian heirloom beans ( 0.5625 g water loss / bean)?

    How does the density measurement factor into any of this?

  12. Rudel Balatbat says:

    Hi Joe do you use PVC pipe as way to measure density? May I ask how reliable is the result I get from it?

  13. Ricardo Mesquita de Abeci says:

    Guys, great work you are doing!!!
    Thanks for sharing!

  14. Awak Coffee says:

    We learn so much about roasting from your videos. Thank you so much Joe & David, salute from Medan, Indonesia

  15. Sam Rasmussen says:

    Does anybody have information concerning the sources he references at 13:39 ish?

  16. vyapada says:

    Water is still present in roasted coffee – it doesn't disappear during "drying" and weight loss is consistent throughout the entire roast…

  17. Zeris Coffee says:

    14-18ºF de progresion? Grados Cº???

  18. risdiansah21 says:

    Hi Joe, just watched you video… its very awesome. I have a question. You said the amount of time from green to yellow doesnt effect the flavour…and the range you said generally between 4-6 minutes, my questions is after we reach yellowing point in that range of time, should we increase the heat or lower the heat or make it the same till we hear first crack? Thanks! 🙂

  19. sitaram napit says:

    hi sir this is sitaram from dubai I love all of this training video this all are so good for learning. I have still confused in what should be rate of heat once we dump the green bean in the roaster and how we can analysis it. would you please help me in this topic

  20. James Patton says:

    You should switch the time and …oh never-mind I see this comment

  21. Will Stevens says:

    So when you use a graduated cylinder to measure volume of a solid, you have a problem of the air gaps between the beans. This is dependent on size/shape/packing of the beans. Would it be better to measure the mass of a sample and then submerge the sample in alcohol or low density fluid and measure volume by difference?

  22. Marc Bell says:

    Thank you for dumbing the lessons down. You are a good teacher mate.

  23. Akshay vaidyanathan says:

    Thanks for this hugely informative video! I m a home roaster roasting in a convection oven with a drum attachment. Roasts are 16-17mind long on average using the principles you mention (slowing the drying for dense beans) is that too long a roast time?

  24. Ke Wei says:

    The best way to measure density is with the displacement method in a graduated cylinder. Weigh out a 100.0g sample of your green coffee. Fill you graduated cylinder with enough water that when you put in the 100g of coffee the water will cover it completely. Measure the volume of water in the cylinder and write it down as "initial volume". Put the green coffee in the graduated cylinder with the water. Record the new volume reading as "final volume". The difference between the final volume and initial volume of the water is the volume of the 100.0g sample of coffee. Divide 100.0g by that volume to get a reading in units of g/mL (water = 1.0).

  25. JGMDSN 66 says:

    A LIKE just for the "…that looks like more of a tongue or a butt…" lol

    Okay, actually gave a like before that, but I do like the TONGUE in CHEEK humor…

    Sorry to all for that…(hoping that coffee roasters have a silly sense of humor… 🙂

  26. Kyle Rutherford says:

    Why would you use a pipette? I think you mean a beaker, perhaps?

  27. Mayur Karanth says:

    Seriously, I can't thank k you guys enough for this video. Keep em coming.

    -coffee planter from India.

  28. Lars Györvari says:

    Fantastic content. Thank you!!

  29. ElkEars says:

    re: pipette drawing. mg is weight, not volume.

  30. James Adams says:

    When the beans are turning yellow and have burnt spots, is there anything that should be done to keep the burnt bean taste from happening or is this just something that comes with roasting?

  31. James Adams says:

    When the beans are turning yellow and have burnt spots, is there anything that should be done to keep the burnt bean taste from happening or is this just something that comes with roasting?

  32. Márcio Costa says:

    Tks for the videos, guys, I've just began to watch these 2, and will keep watching the others. Regrets from Brazil!!

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