(Hopefully) Useful Home Roasting Tips - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
Ken Fox (original poster)

#11: Post by Ken Fox (original poster) »

Fullsack wrote:<image>


To take this a step futher, pick the defects out before roasting. Insect damage, fungus damage and broken or chipped beans can give your roast a dirty, sour or moldy flavor. These little varmits were plucked from only 225 grams of a blend supplied by a well regarded purveyor of green beans for home roasters.

Advantage home roasters: we have the time to do this kind of thing.
Doug,

Those are some ugly looking beans! I've had some beans with a lot of defects, but the beans you photographed are worse than anything I can recall roasting, certainly within the last few years. Just on sight alone, and without regard to who was selling them, I'd make a point of not reordering any coffee that looked like THAT!

ken
What, me worry?

Alfred E. Neuman, 1955

Ken Fox (original poster)

#12: Post by Ken Fox (original poster) »

mrgnomer wrote:
I had an iRoast2 for about 3 years before the Hottop. The Hottop I've had for about a year now. I'm noticing there's a stage between about 370F to 390F depending on how steep the heating ramp is to that temp where there's a sweet smell that comes out.

I'd really like to preserve that sweet smell in a roast to bring it out in a good espresso extraction. My rest from 1st to 2nd has been very short; usually under 2 min. From your points it looks like backing off on the heat at the start of 1st crack should bring the chamber temperature down to extend the rest without stalling the roast in 1st crack. You think I could get sweetness to come out more with a longer rest to 2nd?
One man's "sweetness" is another man's (fill in the blank). I find it a little hard to extrapolate what I might smell during a roast with what I'll taste brewed from it later, even if Schomer has a cliché out there about wanting espresso to taste like coffee smells.

My experience is (at least with my roaster) that if the period between onset of 1st crack to beginning of 2nd crack is short, like 2.5 minutes, that the flavors become multidimensional and "flat." Almost anything that tastes really good will have a whole lot of different flavors that coalesce to make a very nice, harmonious, impression. This is true of any great wine (where this characteristic is called "complexity,") and of most any good dish in a fine restaurant (or even the local Thai place). When this complexity is lacking, things taste flat, and that is what I get from coffee roasted with too short an interval between onset 1st and onset 2nd.

In my post I avoided using absolute temperature numbers since these will differ depending on what type of roaster one uses and where the probe is situated. My temperature probe seems to be located in an especially hot part of the drum and reads about 14 degrees F higher than it should judging by bean appearance at any given point in the roast. Because this reading is constantly high, it is easy to correct for it and to become used to the numbers which are not correct in an "absolute" sense but remain quite useful for controlling a roast.

The key point is to try to use thermometry if at all possible and to learn, by experience, what the numbers mean in the context of one's specific roaster. Once you have this, you can tinker around with your roast profile and then taste your results. If the results are good you can then easily repeat the roast parameters later because you will have real time data you can then impact by adjusting the heat source so that you get the same profile again at a later time.

ken


ken
What, me worry?

Alfred E. Neuman, 1955

Abdon

#13: Post by Abdon »

I think (therefore I could be horribly wrong) that messing with the temperature before a good roaring 1st crack is dicey at best. All through half-way 1st crack, beans are for the most part soaking up heat; drop the heat and they will cool off rapidly. Depending on your roasting method, keeping up a target temperature around this point in time is tricky and opens the door to inconsistency. At a point into 1st crack beans expand and begin to radiate heat. Slowing down the roasting on this stage is fairly easy because the beans will be working with you, not against you.

If you take first and second crack as milestones in the roasting process, that point after 1st where the beans suddenly begin to gain heat at a faster pace is another milestone that is just as important. This is where is the easiest to consistently slow down your roast between first and second.

For me there are two kinds of coffees, those that like to ease their way to the finish line, and those that improve by a slower roast with a sharp up turn at the end. They may both end up at the same roast level and even the same time, but will taste different.

Ken Fox (original poster)

#14: Post by Ken Fox (original poster) »

Abdon wrote:I think (therefore I could be horribly wrong) that messing with the temperature before a good roaring 1st crack is dicey at best. All through half-way 1st crack, beans are for the most part soaking up heat; drop the heat and they will cool off rapidly. Depending on your roasting method, keeping up a target temperature around this point in time is tricky and opens the door to inconsistency. At a point into 1st crack beans expand and begin to radiate heat. Slowing down the roasting on this stage is fairly easy because the beans will be working with you, not against you.
This is an example of something that is going to vary depending upon the sort of roaster one uses. There are roasters that are "underpowered," which struggle to reach first crack before 10, 12, or even 15 minutes. My roaster was like that when I first received it, as the supplier (in spite of my making this issue crystal clear before purchase) failed to put a burner in the roaster that could supply enough heat at altitude. I live at almost 6000 feet/~1850 meters, and there are serious combustion issues when one lives appreciably above sea level. As originally configured, my roaster could hit first crack at 9 minute only if I had the heat on full bore and it was a warm summer day with ambient temps above 70F. Since I have to roast in cooler temperatures than that, and since I want to have control over the process, I was successful (with Barry Jarrett's help) in finding a replacement burner that more than doubled the available heat.

Roasting with my sample roaster is a totally manual process; I decide how much heat to supply so there is no issue with "messing with the temperature," rather I have to decide how much heat is applied for each and every second of my roasts, both before and after first crack. Each and every part of the roast profile can be controlled if you have control of the heat input (and/ or the airflow).

In a situation where one does not have control over this factor, either due to an inadequate heat source or lack of manual control, then this is an area that will demand compromises.
Abdon wrote:If you take first and second crack as milestones in the roasting process, that point after 1st where the beans suddenly begin to gain heat at a faster pace is another milestone that is just as important. This is where is the easiest to consistently slow down your roast between first and second.
My experience in a totally manual setup is different. My impression is that the beans rapidly gain heat because the heat source has finally gotten cranked up to full power, and it is easy to have a bit too much heat being introduced into the process and in that way to "get ahead of one's self." With my drum this happens because I've had to crank up the heat to hit first crack by 8 or 8.5 minutes (my typical roast parameter), and in doing so I am applying quite a bit of heat just beforehand, which translates into retained heat in the massive drum. Air roasters will act differently and can be adjusted more rapidly. I deal with this by anticipating what is going to happen next, e.g. I back off the heat in the minute or so before the onset of 1st so that this doesn't happen.

There IS a point in the roast where the beans become "exothermic," i.e. one can turn off the heat source and the beans will keep rising in temperature without additional added heat. With my roaster this occurs during the last degree or two or maybe 3 (F) before I end the roast, and it might actually be more that the drum is continuing to transfer heat to the beans, heat that was added beforehand. With an air roaster, if one left the blower on but killed the heat, you would probably not observe this behavior because then the blower would start to actually cool off the beans and work against this process.
Abdon wrote: For me there are two kinds of coffees, those that like to ease their way to the finish line, and those that improve by a slower roast with a sharp up turn at the end. They may both end up at the same roast level and even the same time, but will taste different.
I haven't observed this but then we might well roast different coffees, and to different roast levels.

ken
What, me worry?

Alfred E. Neuman, 1955

Abdon

#15: Post by Abdon »

Ken Fox wrote:

This is an example of something that is going to vary depending upon the sort of roaster one uses...
Indeed. When I moved overseas I found out that the electric grid is woefully underpowered (rated 100v@50hz, fluctuating up and down from there) so I went back to a stove top cast iron chamber. I'm still in the process of building a crank agitator with a mechanical advantage of 7:1, but the current setup uses a custom made wisk that is shaped the same as the sides of the chamber, and is half the width of the chamber. This setup has a fitted high domed lid with a hole that is also half the width of the chamber. When the wisk is moved around, it can touch the inner walls of the chamber as well as move about the beans on the middle. Following suggestions found on this very forum I drilled holes on the bottom and it improved positive air flow (hot air from the gas grill, as opposed to cold air from the top) quite significantly. The ideal capacity is around one pound. Monitoring heat is accomplished with an infrared thermometer that takes just half a second to tell me the surface temperature of the beans.

Ken Fox wrote: Roasting with my sample roaster is a totally manual process; I decide how much heat to supply so there is no issue with "messing with the temperature," rather I have to decide how much heat is applied for each and every second of my roasts, both before and after first crack. Each and every part of the roast profile can be controlled if you have control of the heat input (and/ or the airflow).
When I said 'messing with the temperature' I meant it in the sense of it being best to leave it alone at that particular juncture.
Ken Fox wrote:

My experience in a totally manual setup is different. My impression is that the beans rapidly gain heat because the heat source has finally gotten cranked up to full power, and it is easy to have a bit too much heat being introduced into the process and in that way to "get ahead of one's self." With my drum this happens because I've had to crank up the heat to hit first crack by 8 or 8.5 minutes (my typical roast parameter), and in doing so I am applying quite a bit of heat just beforehand, which translates into retained heat in the massive drum. Air roasters will act differently and can be adjusted more rapidly. I deal with this by anticipating what is going to happen next, e.g. I back off the heat in the minute or so before the onset of 1st so that this doesn't happen.

There IS a point in the roast where the beans become "exothermic," i.e. one can turn off the heat source and the beans will keep rising in temperature without additional added heat. With my roaster this occurs during the last degree or two or maybe 3 (F) before I end the roast, and it might actually be more that the drum is continuing to transfer heat to the beans, heat that was added beforehand. With an air roaster, if one left the blower on but killed the heat, you would probably not observe this behavior because then the blower would start to actually cool off the beans and work against this process.
It is hard to compare apples to apples (roasting methods to roasting methods) and even if that was the case, observable events are open to interpretation. Thank God we can compare notes and share what we have seen :D

My setup does not enjoy the thermal mass of yours, which means that if I screw with things at the worst possible time, I can taste the fruits of my mislabors. My observation has been that as long as the beans have humidity to shed, that they have the means to self cool. The energy released as water vapor quickly raises away from your roaster. Once humidity is mostly gone, they begin to radiate heat (the endothermic to exothermic thingie). This heat does not travel as far, and for the most part just gets trapped on the roast chamber.

Messing (altering) the temperature while the beans are endothermic is tricky; it is easy for the beans to shed some heat while you are lowering the temperature and become baked. Messing with the temperature while the beans are in radiating mode is more consistent, as they self regulate better.
Ken Fox wrote:

I haven't observed this but then we might well roast different coffees, and to different roast levels.
I have found (or have myself deluded into believing to have found) different nuances on coffees that can be roasted very dark. The most recent coffee I have been roasting like this is a Ethiopian Harrar lot #14-something from Sweet Marias. One way, there are roasted caramelly flavors with a hint of tobacco. The other less caramel with very strong dry tobacco flavors. You have a more consistent setup; could you run two batches, one with a steady march towards the end, the other with a slower gain, ramped up to speed in the last 30 seconds or so?

BradS

#16: Post by BradS »

Excellent subject and content, Ken & others. I have been playing with the very issue(s) you mention concerning time between 1st & 2nd, and in addition; cooling time. Both had been relatively short in my roasts, as I was usually getting about 60-90 seconds between 1st & 2nd, and, in my ignorance, originally tried to cool the beans (and remove the chaff) asap at the end of roasting. I'm hoping you'll take the time to critique the roast profile shown in the information below. This was roasted Saturday and I sampled the first shot this morning which seemed to have a lot more mellowness & personality than my previous roasts (this was also the first roast with a variac which I used to slow down the sprint from 1st to 2nd).



The shallower decreasing slope at the end of the roast was where I turned off the heat and left the fan running with the variac back at full (130VAC) to see if cooling could be done in situ with any degree of success. You can see - I got impatient and opened the roaster and dumped the beans! There is some more information on the roasting label below, mainly that I decreased the voltage from 110V to 105V to slow down the roast from 1st to 2nd... with fairly good results. I also seem to have a higher-than-normal offset on my temp reading as my temps seem about 40 degrees high compared to visual/audible cues.



I think that, based on the taste of this roast (much less sharp with more body and, well, taste) that I'm on the right track, but It's always nice to have an honest critique. I'd also like to ask other SC/TO users what their best success is with roasting repeatably. I think the variac will help me immensely, as I roast either on the back patio whenever possible or in the garage when necessary due to weather. I get much faster roasts in the garage for whatever reason, maybe either line voltage or ambient conditions, I don't know yet as I haven't used the variac in both places.

In any case, thanks again for all the information you share here.

Cheers,

Brad

Ken Fox (original poster)

#17: Post by Ken Fox (original poster) »

Abdon wrote:I have found (or have myself deluded into believing to have found) different nuances on coffees that can be roasted very dark. The most recent coffee I have been roasting like this is a Ethiopian Harrar lot #14-something from Sweet Marias. One way, there are roasted caramelly flavors with a hint of tobacco. The other less caramel with very strong dry tobacco flavors. You have a more consistent setup; could you run two batches, one with a steady march towards the end, the other with a slower gain, ramped up to speed in the last 30 seconds or so?
Roasting on my roaster is somewhat akin to maneuvering an oil tanker; it responds much more predictably and well to moves made in advance of when you want them to happen. I already go very slowly from the onset of first crack to when I terminate my roasts, generally a few seconds before 2nd would start. Since I'm striving for 3.5 to 4 minutes after the onset of 1st to the end of the roast, I'm not at all sure that I could even test your second profile without stalling out the roast. This may be an unchangeable behavior of drum roasters which have significant thermal mass in comparison to the bean charge. It is easy with my setup to go faster than I go now during this time period, but relatively difficult to go slowly.

ken
What, me worry?

Alfred E. Neuman, 1955

coffee_monkey

#18: Post by coffee_monkey »

Abdon wrote:Messing (altering) the temperature while the beans are endothermic is tricky; it is easy for the beans to shed some heat while you are lowering the temperature and become baked. Messing with the temperature while the beans are in radiating mode is more consistent, as they self regulate better.
There are only two period where beans become exothermic - 2nd half of 1st crack and 2nd crack. How can you profile roasting if you don't "mess with the temperature' outside of those two periods? Do you just put on full flame and let it rip?


Ben
Ben Chen

Ken Fox (original poster)

#19: Post by Ken Fox (original poster) »

BradS wrote:Excellent subject and content, Ken & others. I have been playing with the very issue(s) you mention concerning time between 1st & 2nd, and in addition; cooling time. Both had been relatively short in my roasts, as I was usually getting about 60-90 seconds between 1st & 2nd, and, in my ignorance, originally tried to cool the beans (and remove the chaff) asap at the end of roasting. I'm hoping you'll take the time to critique the roast profile shown in the information below. This was roasted Saturday and I sampled the first shot this morning which seemed to have a lot more mellowness & personality than my previous roasts (this was also the first roast with a variac which I used to slow down the sprint from 1st to 2nd).
One aspect of my roaster did not make it into my original post; e.g., cooling. The cooling tray on my roaster is if anything over-ventilated, and as a result, the beans cool down to room temperature very very fast. I typically leave the beans on the cooling tray for 2 minutes, by which time their temperature is no more than 10 or 20F degrees above (and often equal to) room temperature. They then go into a wire mesh basket and are taken outside for vigorous dechaffing by a vertical floor fan. The result is that they are COOL less than 3 minutes after the roast ends. My personal opinion is that rapid cooling is a generally good thing, as it allows you to accurately choose the roast level without the roast level advancing when the beans are supposed to be cooling down.
BradS wrote:
The shallower decreasing slope at the end of the roast was where I turned off the heat and left the fan running with the variac back at full (130VAC) to see if cooling could be done in situ with any degree of success. You can see - I got impatient and opened the roaster and dumped the beans! There is some more information on the roasting label below, mainly that I decreased the voltage from 110V to 105V to slow down the roast from 1st to 2nd... with fairly good results. I also seem to have a higher-than-normal offset on my temp reading as my temps seem about 40 degrees high compared to visual/audible cues.
It is hard for me to give any useful feedback regarding a roast I have not tasted, and being entirely honest there are a number of other HB regulars who probably could give you better tasting feedback on a roast than I could. I'm not really knowledgeable about SC roast parameters, and hopefully someone else can give you some meaningful feedback.

ken
What, me worry?

Alfred E. Neuman, 1955

Abdon

#20: Post by Abdon »

coffee_monkey wrote:

There are only two period where beans become exothermic - 2nd half of 1st crack and 2nd crack. How can you profile roasting if you don't "mess with the temperature' outside of those two periods? Do you just put on full flame and let it rip?
Ben
I was referring to the period before 1st crack, and in particular with the way/equipment I roast. Different ways of roasting will let you get away with different things. I wish my system had more thermal mass, but on the other hand the method I'm currently using allows for fine and controllable changes in temperature.

I roast on a cast iron chamber (pan, 27cm circumference) with small holes on the bottom, that has a fitted cast iron lid with a hole on the top. The aim for the setup is to build up internal chamber temperature as close as possible to the metal temperature. After a long warm up the bottom of the chamber is at 475 degrees Fahrenheit, the outside top of the lid at 220 degrees. I use an infrared thermometer so I don't know the mean chamber temperature.

My aim is for an 8 minutes to first crack.I would warm up to 475+ bottom of the chamber temperature, pull the heat a bit, and dump one pound of beans. After about a minute I would bring up the heat to cruising speed and monitor progress. If I were to bring the heat higher I would begin to get scorched beans, not a pretty sight. My goal is to consistently go from green to pale to browning and on to first crack without damaging (burning) the surface of the beans. Once I hit toasted bread smell I know whether I need to ramp up the temperature to achieve the +/- 8-minute first crack goal. Sub 8-minute first crack is fine if the roast looks even, way more than 8 minutes and it became an exercise in bean baking and not bean roasting :roll:

The 'messing with temperature' comment is more in line with my own roasting methods and mistakes. I used to fiddle with temperature on my way to first crack. For my method it gave very inconsistent results; my observation was that as long as the beans had the capacity to cool off via steam, lowering the temperature at this stage would destroy the balance between metal surface and chamber temperature, introducing inconsistency at best and baked beans at worst. From there I learned to hit the sweet spot temperature wise, and to fine tune it with agitation. Once the beans are somewhat dry, half way past first crack, they will let me get away with more fiddling of the temperature as they would not be able to take advantage of temperature drops.

Once first crack is underway I drop the temperature and monitor bean surface temperature via the infrared thermometer. The goal is for them to never drop temperature, just to gain temperature at a steady pace. Around four minutes to second crack works fine, either via slow buildup and a sharp up turn at the end via more flame, or a steady cruise.

I built my roasting chamber when I moved to Japan, as a expeditious way to get back into roasting my own beans. It worked so well that eventually I gave up on other means, whether home built or store bought. My most important goal was consistency, and this method allows me to accomplish that. I can see what the beans are doing at every stage, I can smell every step of the way, every time I ramp up the temperature after 1st crack I can feel the heat raising through the top hole, and adjust agitation accordingly. Through agitation alone I can adjust whether the beans gain 10 or 15 degrees in a given minute.