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JackH
OfflineAdmin
· 08/06/2020 3:33 PM
Allenb, how are you doing?

Oneal
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· 08/05/2020 1:08 PM
Is anyone roasting on a Coffee Tech FZ 94? Using Artisan. Need help. thumbdown

mtbizzle
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· 08/03/2020 11:26 AM
There is (or was? Grin ) a gesha at sweet marias...

snwcmpr
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· 07/25/2020 12:31 PM
I ran out of Ethiopian Gesha.

snwcmpr
Offline
· 07/25/2020 12:31 PM
it is ok. I do not remember. I think it was a callout to the spam shout.

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Cast Iron Wok roasting - triage
ToastyRoast
I've been experimenting with roasting in a cast iron wok (using a wok shovel) with some mixed results. The beans grind to a surprisingly light brown relative to the skin. Additionally the grind seems more fibrous and inconsistent (from an Encore) than what I'm accustomed to from local roasters and is clogging paper filters even on more coarse grinds.

Both a Sumatra and Ethiopia from Sweet Maria's turned out this way. I'm fairly certain I under roasted the Ethiopia (15 minute roast, 1/2 lb, issues with it clogging the grinder after settling for a week). Both at a glance seemed to under extract when brewing but had surprisingly noteworthy cocoa and no strong grassiness I'd expect with under roasted coffee.

I'll include other details on the roasts below, please let me know if there are stand out issues.

Ethiopia:
Preheated wok to 500°F. Added 1/2 lb of beans. Roasted 15:08min, pulled when nutty aroma gave way smokey (prior to 2nd crack).

Sumatra:
Preheated wok to 500°F. Added 1lb of beans. Roasted 25:07min. Didn't hear 1st or 2nd crack, stopped when beans had browned and buldged with apparent cracking at tips. Ended with a peanut butter cookie aroma.

Not sure the final temperature on either as I couldn't find a suggested final temperature.
 
renatoa
Welcome

How was the agitation of beans done ?
Is the most important factor in coffee roasting, "keep beans moving" is the mantra that every roast method must obey the first.
 
pisanoal
Welcome to the forum!

I would suspect the uniformity of the roast was not all that great (both bean to bean, and inner and outer of individual beans). The inner development of the bean definitely did not match the outer as shown by this statement "The beans grind to a surprisingly light brown relative to the skin." Also, lighter roasted coffees can have more uneven grinds. You may not think you roasted light based on outer color and roast timing in regards to 1C and 2C, but with uneven roasts, its highly likely you had some pretty light beans in there as well as the inner bean. Improper roasting can also "dry out" a bean. ( I don't know if actually dries them out, but I've noticed on beans I've messed up, when i eat a roasted bean it leaves a dry, ashy feel vs when I've gotten good results it leaves more of a slight oily feel). Both of these can cause excess fines which will cause filters to blind over. I have noticed that Ethiopian coffees tend to do this more readily then others as well (some of that is due to tendency to roast lighter with ethiopians, but also its a harder bean in general).

Also, skillet roasting's main method of heat transfer is obviously conduction, and the surface of the beans is subjected to relatively large temperature gradients when compared to other roast methods. That's not to say other methods don't have similar roasting characteristics (drum roasters), but the relative amount of bean mass in contact with the hot surface is going to be higher in a skillet/wok roasting method then a drum. Another technical note, when inner bean development seems lacking compared to outer bean development, it can mean too high of a charge temperature and your roast progressed too fast at the beginning not allowing sufficient heat saturation into the inner bean. You may try reducing the heat at the beginning and then adding more heat a few minutes in.

Like renatoa said, sufficient agitation of beans is key. If you could agitate the beans enough so that they all heat uniformly, you could in theory get excellent results. Its just much harder to accomplish this in a skillet type roasting scenario.

I would also say based on roast times 1 lb was too much to try roasting that way. 1/2 lb seemed about right at 15 minutes.

I have only roasted that way a couple of times just for the heck of it. I'm not convinced on its merits as a method to roast anything other then mediocre coffee, but some of that I'm sure is bias. Hopefully others who skillet roast on a regular basis and get good results can chime in on more specifics.
 
renatoa
Check Hive roaster, to have an idea how should look a much better design of a machine done with this type of heat transfer in mind.
 
pisanoal

Quote

renatoa wrote:

Check Hive roaster, to have an idea how should look a much better design of a machine done with this type of heat transfer in mind.


Well that thing is super cool... Can't say id like "swirling" it for 10-15 minutes, but definitely a huge upgrade for not much $.

Excellent intro to home roasting.
 
ToastyRoast

Quote

renatoa wrote:

How was the agitation of beans done ?
Is the most important factor in coffee roasting, "keep beans moving" is the mantra that every roast method must obey the first.


Agitated with a wok shovel, https://imgur.com/kYD4dft for reference.. I kept at about that pace for the full roast.

Quote

pisanoal wrote:

I would suspect the uniformity of the roast was not all that great (both bean to bean, and inner and outer of individual beans). The inner development of the bean definitely did not match the outer as shown by this statement "The beans grind to a surprisingly light brown relative to the skin." Also, lighter roasted coffees can have more uneven grinds. You may not think you roasted light based on outer color and roast timing in regards to 1C and 2C, but with uneven roasts, its highly likely you had some pretty light beans in there as well as the inner bean.


I think the outer bean seems fairly uniform, but your description for the inner been being under developed sounds spot on. See image below...

i.imgur.com/NYntaeC.jpg


Quote

pisanoal wrote:

Improper roasting can also "dry out" a bean. ( I don't know if actually dries them out, but I've noticed on beans I've messed up, when i eat a roasted bean it leaves a dry, ashy feel vs when I've gotten good results it leaves more of a slight oily feel). Both of these can cause excess fines which will cause filters to blind over. I have noticed that Ethiopian coffees tend to do this more readily then others as well (some of that is due to tendency to roast lighter with ethiopians, but also its a harder bean in general).


I decided to bite the bean on this and found it more like a hard candy, compared to a known good roast which I would describe as similar to a thick cracker.


Quote

pisanoal wrote:

Also, skillet roasting's main method of heat transfer is obviously conduction, and the surface of the beans is subjected to relatively large temperature gradients when compared to other roast methods. That's not to say other methods don't have similar roasting characteristics (drum roasters), but the relative amount of bean mass in contact with the hot surface is going to be higher in a skillet/wok roasting method then a drum. Another technical note, when inner bean development seems lacking compared to outer bean development, it can mean too high of a charge temperature and your roast progressed too fast at the beginning not allowing sufficient heat saturation into the inner bean. You may try reducing the heat at the beginning and then adding more heat a few minutes in.


Are there any go to target bean temperature at different points in the roast? I wasn't able to find any before getting started and I think that would have helped know when things were going wrong.
 
pisanoal
In the picture you posted, the color of the grind is of course very light compared to the outer color. Also, looking closely at the beans themselves it looks like the majority of them have not undergone first crack. The beans, while darkish, look waxy and un-expanded. Notice the tops of the beans (where the split is) are very flat. There should be a slight concavity to them when roasted. The texture of the bean again is waxy looking instead of having a matte or satin type finish to them. All of these indicate underdevelopment even though color seems to be there. Check out the photos in this linkhttps://www.sweetmarias.com/roasting-...uideV2.php . Most of your beans look closer to the 393 F mark instead of the 426 F mark which is about the earliest most would consider pulling a roast (bean and person dependent). Disclaimer: Temperatures are very subjective to how and where you are taking the temperature as well as roast method (some methods are better for determining bean temperature then others). I would not consider these temperatures to be accurate reflections of what to shoot for at these stages, but you need to do some trial and error on your own "machine" to learn this. Most of my first cracks are between 380-395 and wrapping up 10 - 15 degrees after that.

I cropped your picture and circled beans that look more developed and potentially have cracked based on appearance in red (to the best i can tell from the picture). The ones that look underdeveloped and have not yet reached 1C are in blue. Excuse the sloppy circles, trackball mice are not good for drawing...

You mention when biting the beans they are more like hard candy. Typically the darker the roast, the "softer", more brittle, the bean gets, what you described as "thick cracker". Under-roasted beans would be harder as the cellulose structure hasn't really opened up yet. Another sign of approaching and going through 1C would be a rapid expansion in bean bed volume indicative of the individual beans expanding.

How are you checking temperature?

For your last question, the picture with temps is a decent guide. However, keep in mind temperatures vary widely based on what i said above. Certainly the temperature ranges between the stages are fairly applicable. For example, i would say for my roaster subtract between 10-20 degrees for my observed color stages.



Hope this all helps! Other's please feel free to critique my understanding.
pisanoal attached the following image:
picture_of_roast.jpg
 
Mathew
The Hiveroaster is very easy to agitate, the action is like riding a bicycle. The design provides very very even roasts, and the convection action combined with the hot surface of the hive roast with the same or similar results to a commercial roaster. Any profile can be achieved, from very light and bright 7 minute roasts, to full dark at 14.
 
renatoa
How hard would be to adapt a kitchenaid mixer to do the agitation while you are watching ... Grin
I seen even a baby bed rocker done this way, lol
 
JackH
It looks interesting. Too bad it only has a 6oz capacity.
---Jack

KKTO Roaster.
 
ToastyRoast

Quote

pisanoal wrote:

How are you checking temperature.


Infrared thermometer, checking the cast iron wok at different locations.

In the last couple roasts I wasn't paying close attention to the bean temperature and instead opt to measure the cast iron wok and roast duration. I didn't take notes on the beans but I'm fairly certain they never went over 400F so that would explain the underdevelopment.
 
pisanoal

Quote

ToastyRoast wrote:

Quote

pisanoal wrote:

How are you checking temperature.


Infrared thermometer, checking the cast iron wok at different locations.

In the last couple roasts I wasn't paying close attention to the bean temperature and instead opt to measure the cast iron wok and roast duration. I didn't take notes on the beans but I'm fairly certain they never went over 400F so that would explain the underdevelopment.


That's what I assumed you were using but wanted to check.

I would say that measuring the wok temp isn't going to tell you anything about how the roast is proceeding. I'm assuming that you are using that measurement just to make sure your wok doesn't get too hot?

It may be interesting to check bean temperature, but honestly i think your best bet in this case is to use your senses to pick up on roast development. Look for color, bean expansion, visual signs of first crack. Listen for rolling 1c and start your "timer" as to how long you want to wait after 1C to pull the beans. Pay attention to how the roast smells. If it still smells green during roasting, it probably is (this is more an experience thing that you will have to learn). If you are pulling the beans sometime after start of 2C, obviously use that as your development mark to start timing. Even then it would be useful to get a time on end of 1c to beginning of 2c for batch to batch comparison.

For the same bean, you can also pick up on when it starts to blow its chaff compared to when 1C starts. This is different from different sources but its pretty reliable batch to batch within the same bean type. Some will start dropping chaff very early on. Some have a couple of phases where they drop chaff like crazy, some drop it right before or during 1C, it all depends, but watch out for it as another clue for how far along the roast is.

Have you roasted any more since your original post?
 
ToastyRoast

Quote

pisanoal wrote:

I would say that measuring the wok temp isn't going to tell you anything about how the roast is proceeding. I'm assuming that you are using that measurement just to make sure your wok doesn't get too hot?


Exactly that.

Quote

pisanoal wrote:

It may be interesting to check bean temperature, but honestly i think your best bet in this case is to use your senses to pick up on roast development. Look for color, bean expansion, visual signs of first crack. Listen for rolling 1c and start your "timer" as to how long you want to wait after 1C to pull the beans. Pay attention to how the roast smells. If it still smells green during roasting, it probably is (this is more an experience thing that you will have to learn). If you are pulling the beans sometime after start of 2C, obviously use that as your development mark to start timing. Even then it would be useful to get a time on end of 1c to beginning of 2c for batch to batch comparison.


I do remember pulling the beans because I thought the smell was transitioning from a peanut butter cookie into a burnt aroma, but I might be over sensitive to that due to over roasting (years ago on a whirley pop).

Quote

pisanoal wrote:

For the same bean, you can also pick up on when it starts to blow its chaff compared to when 1C starts. This is different from different sources but its pretty reliable batch to batch within the same bean type. Some will start dropping chaff very early on. Some have a couple of phases where they drop chaff like crazy, some drop it right before or during 1C, it all depends, but watch out for it as another clue for how far along the roast is.

Have you roasted any more since your original post?


Not yet, wanted to get a better understanding of what went wrong first (thanks for that!). I'll probably do so in the next 1-2 weeks.

Not expecting positive results but I'll double roast the beans I have, not much to loose at this point so might as well make it an experiment. After that I have 3lbs of green to continue with, so I'll keep this post updated as I go. :)
 
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