Who is here? 1 guest(s)
 Print Thread
Roasting 101 Basics
allenb
Roasting Basics

The following 'basics' primer on coffee roasting was compiled from previous posts from Seedlings


Good article covering some of the basic progressions of a roast

Heating the green coffee should bring the beans to "First Crack" also known by "1C" or "FC" in 8 to 12 minutes. Sufficiently heating coffee beans changes the internal chemical composition in a similar manner as popcorn, and as the woody material (cellulose) of the bean heats up, the moisture will be released. This produces an audible "pop" similar to popcorn, but not as loud. Each bean will crack. Like popcorn this will start with a pop or two, then steadily progress to a "rolling crack" or a persistent popping, then taper off to a pop or two until first crack has finished. The conclusion of the first crack leaves a very light roast of coffee ready for grinding and brewing. This is commonly known as a "City" roast in roasting circles. Of course the coffee can be roasted darker if desired.

If a darker roast is sought after, keep roasting, watching, listening and smelling. At the onset of 1C the aroma turns from grainy, grassy, cereal smells and wispy smoke begins to develop. By the end of 1C, smoke will grow steadily stronger as will the aromas, until "Second Crack" begins. Yes, coffee cracks once, then cracks again as the roast progresses! The onset of 2C will bring continuous and darkening smoke, a sweeter, more intense aroma, and snap-crackling. 2C sounds less like the popcorn pop, and more like the crackle of snapping toothpicks or the sound of "Rice Crispies" cereal in milk. It is quieter than 1C. 2C will begin with a snap or two as 1C did and progress to a full crackling, then if roasting continues, fade out. This second crack marks the early stages of darker roasts. Oils in the coffee will be pulled to the surface of the bean. If the roast is stopped just prior to 2C, the roast is called "Full City" and can have a few oil droplets visible on the beans. Stopping the roast further into rolling second crack will yield a "Vienna" roast and the beans should be nearly covered with shiny oil. Stopping at the end of 2C is a French Roasted, very dark coffee. Once second crack has begun, the flavor characteristics that give the coffee bean its fruitiness or acidity, or delicate floral, or sweet chocolate will be caramelized and many of them lost. The resulting dark roast will be marked more by the degree it is roasted than by the distinctness the bean was given on the tree.

----------end article

The following general guidelines are a place to start and intended to assist persons new to roasting.

Preheat your roaster

For all roaster types except fluidbeds, preheat your roaster before charging. Coffee likes to move quickly during the first few seconds of a roast. Start with enough energy to allow reaching a bean temperature of 200F or 94C in 2 minutes. Preheat to an environment temperature anywhere from 300F or 150C up to 400F or 204C. For fluidbeds, begin the roast with a hot air temperature between 300F or 150C and 350F or 175C.

To 300-310F or 150-155C (yellow) is drying phase:
Try to hit yellow somewhere between 3 1/2 and 5 minutes. Too fast brings 'grassiness' in most coffees and 'ashyness' in some low altitude beans such as Brazils, Kona etc. Too slow will flatten or mute the flavors.

Yellow to first crack:
Too fast brings higher perceived sharp acidity, slower brings nuttiness, too slow brings 'baked' flavor

First crack to finish:
Too fast tastes underdeveloped, flat. Too slow through this stage can also bring about a baked flavor.

From 300F or 150C on, the beans should NEVER drop in temperature, always increasing.

The following basic profile is a good place to start for anyone not already familiar with roasting:

-4 to 5 minutes to yellow for drum roasters, small fluidbeds and convection-only roasters can get away with less.

-4 to 5 more minutes to start of first crack 380-410F or 193-210C same as above with small fluidbeds and convection-only roasters, less time is usually allowed.

-1 to 3 additional minutes to end of roast depending on degree of roast level)**

These temperatures are typical for the three major stages of roasting but depending on your sensor type, placement and type of roaster (drum, radiant, convection only), this can vary by several degrees +/-

**For light roasts where there may only be between 15 or 20 degrees from onset of first crack to finish, one should try and allow at a minimum 1+ minutes for proper development.
Edited by allenb on 09/08/2022 11:22 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
addertooth
Those are excellent guidelines. For other new readers, they need to know that some roasters take a bit longer to hit these benchmarks (like full yellow) with roasters such as the Gene Cafe. They can still make rather excellent coffee. They can reduce the time (to yellow) by preheating the empty drum, and rapidly pulling it, filling it with the beans, and restarting.

Be sure to keep roasting logs, and be prepared to pay attention to the details, and learn from the outcomes.
 
allenb
Thanks for mentioning the time constraints of the Gene getting to yellow. I'm sure there are other roaster types that also take a little longer to get to end-of-dry (yellow) but will still produce excellent coffee.

Please feel free to post within this thread, any additional roaster specific tips for the Gene related to hitting good profile benchmarks as well as any other roaster types.

Cheers,
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
zupanjack
Hi, I am new to this forum and new to coffee roasting. This thread seems like a good place for me to start asking questions. I have done about eight roasts so far using different beans each time and so far I am not satisfied with my results. I have a Gene Cafe and prefer fairly dark, thick coffee that I mostly brew as espresso using a super automatic. The directions that came with the machine specified 482 degrees F for 18 minutes to Italian roast. I didn't preheat this first batch. When I got to about 17 minutes the beans turned black and a lot of smoke started to pour out of the machine ( It set off the smoke alarm in the next room). When I brewed my first cup of espresso, the coffee didn't taste burnt, in fact it didn't taste like anything much except for warm water. Subsequent roasts were done backing off of the time and preheating the container. Most have been roasted too light and were pretty acidic. I did one batch to the point of nearly black beans that have a lot of oil on the surface but they don't taste very good either. Is there a very narrow line you have to find to get to the sweet spot?

Reading the directions above do you set the machine to 300 degrees F and hold during the drying phase? Do you boost temperature after drying to get to first crack? Do you keep the temperature rising?

First crack is hard to hear in the Gene Cafe and I haven't always been able to pick it up.

I followed several YouTube videos using the Gene Cafe. In one case they held temp to 420 degrees F for drying and then pushed up to 480 degrees F to finish. Mostly of my roasts so far have been in the 13 - 15 minute range with the temp set to 480 degrees F.

I feel like I am missing something but I am not sure what.
 
HarryDog
Hi Zupanjack, what did you drink before? This might help us point you to some beans. Now when roasting dark, maybe you also want a very bold tasting bean like Sumatra, Indonesian,Costa Rica or Robusta beans, I do enjoy blending in some Robusta for espresso?
 
zupanjack
I use mostly Italian bean coffee. I do a lot of Lavazza and Kimbo. I think it's decent coffee at a good price.

In roasting so far I have used a different bean for each roast. I got 6 lbs free with the roaster and bought a few more different types in one pound lots.
 
renatoa
Welcome !

Sorry if I disappoint you, but the home roasting raising is closely related to the third wave of coffee movement started in the early 2000, as an alternative way to second wave, generally credited to Peet's Coffee, started in the 60s. Today Italian coffee style is paert of second wave, and a lot of us want to forget about them smile
Frankly, I don't know personally any roaster, home or professional, in the specialty realm, who would like today to roast Italian style.
The typical roasters, in the bubble where I am, all search for anything else. Not oily beans as the first commandment Grin
In our local forum, which is very big, 198.816 posts in 8.745 threads, 11.315 members, there is only one, a single thread of those looking for Italian coffees.
All they do is buy and comment about various brands. And complain why nobody local don't want or is able to roast Italian style. Grin

Not the last, @HarryDog is right, Italian coffees is mostly about blends using more or less Robusta, using secret recipes.
One more reason about the difficulty to reproduce them.
 
HarryDog

Quote

zupanjack wrote:
I use mostly Italian bean coffee. I do a lot of Lavazza and Kimbo. I think it's decent coffee at a good price.


Exactly what I was thinking "Kimbo" this coffee is a mystery for me as I have never tasted it. I think you can recreate Lavazza.

You want to get to second crack with your roaster and I read this might be a stretch for the Gene. I'm no help with that. maybe pre-heat as much as possible? Maybe a smaller batch?

Now not knowing the level of darkness you want, I would use Brazil, Indian Monsooned Malabar and Robusta in a blend.
Start with 60% Brazil, 15% Indian Monsooned Malabar and 25% Robusta all second crack. This should get you into the Lavazza range?

I should add you blend these after they have been roasted separately as they will be different sizes of beans.
Edited by HarryDog on 09/24/2024 8:17 AM
 
renatoa
Yes, Gene is a machine that needs a lot of preheating, at least 400F, because a lot of heat is lost when charging.
Would be nice if someone design an alternate roast chamber lid, allowing charge without removing the glass from the machine, as is in the bigger CBR 1200 model, check attached.

The other problem with roasting dark is the lack of info about how to handle the longer development phase, beyond the first crack ending period.
We have a lot of readings about how to prepare the first crack approach, about the first minute in the development phase, but nothing about what to do with the heat at the end of first crack, when the steam released by the beans is gone and the beans temperature resume the rise with an even higher rate than before FC. It's easy to derail at that point and gone straight into SC phase, squeezing the oils from the beans.
renatoa attached the following image:
image_2024-09-24_163524624.png
 
zupanjack
Thanks for the input. I thought from the reading I've done that there has been a trend to lighter roasts to pick up various flavor notes. Descriptions such as chocolate, raspberry etc. are lost on me. I have drunk a lot of coffee in my life and those words have never crossed my mind.

I never considered blending and I would like to try that. I think I should get a few more batches under my belt before I get to that point. I have roasted a couple more 230 g batches since I posted and I haven't tasted them yet. I think I am under-roasting up to this point. The color gets dark pretty fast and I don't know how much development phase I am getting. I burned a couple of batches so maybe I am a little gun shy. One problem I am having is picking up first crack on the Gene Cafe. I tried using my wife's stethoscope on the exit side of the machine but it didn't help.
 
renatoa
To detect FC without any hearing help, a rate of rise meter is required.
Unfortunately, such device can't be bought, as any ubiquitous thermometer.
However, is not difficult to build one DIY, using an Arduino board.
Measuring rate of rise of the exhaust air you can detect a bump near the FC start, followed by a crash, then followed by a recovery, that marks end of first crack, and the transition to second crack.
More detailed reading here: https://oilslickc...ick-crash/ or any other resources you can find about "flick and crash" related to coffee roasting.
 
zupanjack
Thanks for this. This is all new to me so I need to let it incubate for a while. The electronics seems a mystery since I have never done much of that.
I just made another batch this afternoon. I put a piece of grill mat over half of the glass chamber and I could hear 1C distinctly. I ran about a minute past 1C and will see what I've got. The beans still are not dark but I lost 1% more water than the previous batch.

I also put a thermocouple in the exhaust vent to measure exhaust temp. I charged the beans 5 minutes after the exhaust temp was stable.

Anyhow I think I am making progress and learning a lot. I love being on the steep side of a learning curve!
 
renatoa
1 minute past FC is minimal for a medium roast, for espresso you want more.

With a bare temperature measurement you can have an idea of the rate of change counting how many seconds do they go from one degree to another.
This assume you have a thermometer capable to display the degree decimal.
Would not work for a meter that has only units of degrees, without decimals.

Let's get as reference the 6C per minute rate of rise, which equates to 10 seconds for a degree.
When you approach the temperature where you expect FC happen, start a timer on the smarthone, and press lap lap lap... at each grade change.
This is the reason you need decimals, to see very precise the transition from a degree to another.
When you see the lap time decreasing, under 10 seconds, this means FC started. Next, the lap time will increase, this means rate of change crash happens, you are in the middle of first crack... and finally when you see a decrease in lap time again, this signals end of first crack.

At that moment you should decrease temperature trying to maintain the laps around 12 seconds, i.e. rate of rise around 5C/minute... until you reach the desired darkness of the beans.

Not sure how this will be reflected in exhaust temp dynamics, though... all the above is the theory for measurements done inside roast chamber...
 
HarryDog
This video from some sales people give temps and times. Not sure how valid it might be?
Worth a watch to see if it can help you get to a roast level you like quicker.
https://www.youtu...SPoE2qL1ss
 
zupanjack
I wanted to wait until I tried this last batch to respond. I brewed some of this batch and it is pretty good. It still has a bit to go for my tastes but it is the best batch to date. The coffee is a little thin but you can start to pick up some of the heavier flavors of a darker roast.

Regarding temperature I am not sure if measuring the exhaust temp is helpful but it did go up consistently. I know the chamber temp oscillates plus or minus 10 degrees F in a sinusoidal pattern, as the unit works off/on at the heating element. I will continue to monitor to see if any pattern emerges.

I plan to roast my next batch tomorrow and I will stay with the same profile but take to beans further past the first crack. I'm thinking 2-3 minutes if I don't get too nervous as the beans darken.

HarryDog, Thanks for the video. I watched it before and re-watched it. Those times seem too long to me. The times that came with the roaster suggested 18 minutes to 21 minutes at 482 degrees. Somewhere around 17-18 minutes the beans gave off a huge billow of smoke and were oily and black. The coffee had no taste so I threw the batch out. This next batch will push to 14-15 minutes and I'll see how it goes.

Thanks you guys for holding my hand.

Jack
 
renatoa
I am afraid temperature oscillates a lot more, about 40C, almost on-off, at least at heater chamber output, where measured 320-360C.
The cylinder could damp a bit this variation though, especially at the exit.
But the major sedating factor of temperature variations, comes from Gene electronics processing and averaging. And from here a lot of delay in displayed values...
Just measure the sensor itself with an ohm-meter, to see how different it shows compared to the display.

An useful mod would be to mount a LED (12V capable) on the back board relay command wires. Circled in red, see attached...
Will clearly tell you when heater power is on/off... and nothing changes on the temperature display. Useful to draw some conclusions.
...
renatoa attached the following image:
image_2024-10-05_180634761.png

Edited by renatoa on 10/05/2024 10:08 AM
 
renatoa
Sign of the times... in roasting "for traditional espresso"
https://perfectda...ty-coffee/
 
Yasu
renatoa acid
Thank you for the interesting article.
My mornings also start with Long Black, which I put in SIMONELLI MUSICA.
Of course, with my favorite medium roast coffee beans that I roast myself.

Long Black has a richer aroma and stronger flavor than Americano. The secret of this difference lies in which is poured into the cup first. Americano is made by adding boiling water to the espresso, whereas Long Black is made by pouring boiling water into the cup first and then adding the espresso.


Translated with DeepL.com (free version)
 
zupanjack
That was a very interesting article. There is a coffee shop near me that opened about a year or so ago. I think they may roast their own beans. Anyway I had an espresso and it was really astringent, today I might say acid based on my recent reading about the trend to lighter roasts. Anyway he pulled a second shot and it was about the same. Until I bought my Gene Cafe and learned about the trend to lighter roasts and flavor notes, I didn't understand why that coffee tasted the way it did. Seems the trend is shifting back.
 
Jump to Forum: