Why does my roast color look so uneven? Home coffee roasting issues
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- เผยแพร่เมื่อ 7 ก.พ. 2025
- This started as a simple conversation between Chris, Erik and myself, but turned into a 26 min video.
They had roasted the same dry process Ethiopian coffee, one on the Aillio Bullet, the other on the FreshRoast 800. They looked so different! One was very even in color, the other had lighter and darker beans.
We wanted to turn the conversation into a short video ... but as you pull apart the assumptions and issues with roasted coffee color appearance, it's quite a tangle! I ended up with a 26 min. video out of this, breaking out the influence of roast level (dark roasts always look more even), a focus on the variability of dry process aka natural coffees, the presence of chaff, and pretty much everything else. I end up looking at a fancy 90.4 scoring Gesha natural that was probably the most troublesome roast of the whole video (I scored it 87, but the defect cup from the light beans scored 82 for me!).
The process wasn't neat here. But it made me look at my assumptions. Is a roast with bean-to bean color variation a "bad roast?" Does uneven color mean uneven roasting? What does uneven roasting mean anyway? And shouldn't we evaluate coffee by taste in the end, not "eye-cupping" it (which sounds impossibly painful anyway. ) The chapter is not closed on all this....
#homeroasting #greencoffee #roastingcoffee #roastedcoffeecolor #quakercoffee #unripecoffeefruit #coffeedefects #coffeecupping
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Perfect timing!!! I’ve only recently gone down the rabbit hole of home roasting and there is so much to learn.
Moved to Colombia, Now find myself on a coffee farm with very old neglected coffee trees. Very tast though. Started home roasting with a small electric drum roaster. So nice... Thank you guys for your awesome videos. Will be planting Pink Bourbon next week, with many orher trees in a food forrest type setting. Can't wait... Cheers y'all!!!
Hello,
It sound like you fell into a blessing. Would you give me an update after 7 months now.
Have you had any mishaps? What beans are you working with now?
I just ordered 5kg of individual 1kg bags in a variety pack of speciality coffee.
I hope to hear from you. Thank you for the kind reply. 😊😊😊
Thank you for this conversation Tom! I always learn something valuable from you..
Now this is a godsent video that I need right now... Was just wondering why my first roasts looks SO uneven especially roasted light. I guess since I was working with a honey process Ethiopia it just makes sense... Guess I accidentally picked a harder start! I picked very obvious quakers, and the coffee in cup came out fine. Thanks for thses information!
Thank you for this video! Every time when I purchase from a new roaster I wonder in my amateur pourover minds if the beans are unevenly roasted or if it’s the bean itself.
One of the best videos on greens, very helpful. Thanks you very much for pretending to enjoy chewing all these quakers to help us understand. 😘
I learn something today, directly eating the beans to truly tasting the coffee bean, this helps to remove all other variables.😀
High in fiber?
Excellent. Thanks for taking the time to post kind sir.
Excellent. I have been thinking about this topic lately because I roast my coffee in a skillet and usually (but not always) produce uneven (but delicious) roasts.
This was a really interesting video to watch. Thanks for sharing all the photos.
Great conversation, much appreciated 👍
Love the detailed explanation! I've also noticed the drum vs air roaster difference in evenness (I have a Quest drum and Fresh Roast air among others). Even if I match total roast times and development phase its usually the drum that looks a bit more even. I've wondered if air roasters, being almost all high velocity convection, actually 'exposes' how well the green has been picked and sorted, where drums may slightly mask the variation with conduction on the surface of the bean.
I guess that's what I am wondering too. Certain drum roasts seem to produce this more even surface color and a pleasing appearance. But I am separating the issue of "even look" vs "even roast." What I found here, and since I have been focused on this, is the drum roast quakers and semiquakers are less apparent, but seem no less intense than in an air roast where they are easier to spot. -T
Eating the beans to look for differences with uneven roasts is a great idea! I have been working on a home roaster (based on Larry Cotton's designs), and am seeing some coffee come out rather uneven, and some come out looking pretty darn even. I have been wondering how much effect that has.
Wow what great info. I always wondered what was going on. Gave a Xmas gift of a batch that turned out very colorful if you coud call it that. Very festive appearance and they loved it and commented it was great compared to the other home roasted gift they received. 13 years of PopperyII FTW. My first order from SMs' a few days ago!
Very interesting video. I am about to roast and will be eating some Quakers and well-roasted beans to discern the qualities they bring to my cup...thanks!
it's a learning experience!
so if you're going for a more even roast and you're using an air roaster that gives you some control over the heat and fan speed like the SR 540, you could slow the roast down. Virtual Coffee Lab shoots for a 4 minute dry phase in the roast, so on the SR 540, I start out with fan 9 and heat 5, gradually increasing the heat so I end the dry phase at around 4 minutes.
Super interesting, thank you so much for posting!
"1. darker roasts look more even. 2. all the coffee does not ripen in unison. poorer cherry selection or strip picking for commercial coffee. 3. silver skin on naturals tends to darken 4. lack of homogeneity in green coffee, in size and shape can mean different heat transfer in roasting."
I have an alternate solution. I have a Sonofresco and when the chaff screen gets oil or fine chaff build-up after a number of roasts (that brushing does not clear off) then the airflow is significantly diminished and the beans sit on the bottom too long and the top beans don't circulate down as quickly as they normally would. I have observed that every time this occurs is when my roast becomes uneven. Replacing the screen or cleaning it with a solvent removes the build-up and the roaster flows air better and the roast becomes even again. Just pointing out that this issue could come down to something as simple as a thorough cleaning. Overloading the air roaster with too many beans can also produce a similar effect.
Definitely!
food for thought.... awesome
Learn so much even after roasting twenty years, I have an experiment that I do once in a while with surprising good results, just curious if you have tried this method, quite simple it's to do a long slow very low temp pre-heat before starting the actual cooking process at normal starting temps, i hold beans at like just over two hundred for seven minutes First then go into normal cooking process, I am not quite sure what this does? Maybe it soften the inside some? I am looking for technical information from you for what this is doing.
You can take the same coffee and do this method and the same coffee and not and come out with a different cup that is often better with the pre heat depending on the beans (maybe it has something to do with how the beans were processed) thanks great video
I am not sure how you are roasting, but preheating can be very good for even and repeatable results. In our drum sample roaster and 12 kg commercial roaster we always preheat, then roast one batch for "giveaway" coffee before starting our real roasts... -T
This is a very important issue. I also watched the differencies in my drum roasted and in an Aillio roasted beans, which were more evenly roasted. So I assumed ,that there was omething wrong with my roaster or its mixing qualities or the heat source or the drum itself. The greens were washed from Perus! So I think, roaster differences are also causing the phenomenon. Chewing samples is a good idea anyway!
Interesting. In your example of the two piles of ground coffee, one with chaff and the other without, if you used a color meter on those two piles like a lighttells CM 200 would the colors (Antron number) be different?
Yes I think chaff can throw off the roast color measurement numbers ... and is a variable from coffee-to-coffee that isn't always accounted for, just as it influences visuals by a human. You can average multiple readings with a device, and some have this built in as well I believe. We have an older Agtron that does not average, but reads a wide area so it tends to provide consistent readings.
I guess that extension tube could be very useful. It's my next planned upgrade. Also, maybe a phone spectrometer app that measures the bean color is being developed!
Thank you for the video. Love this kind of stuff. Any chance you guys will ever get Aged Sumatra again? I think I got some Aged Java from you guys years ago??? Cant remember but I know it wasnt Sumatra, I only got that once from SM. Unique stuff. anyway. Keep up the good work!
Thank you so much! We don't have any arriving in the next few weeks but we'll let everyone know when we do.
I was just wondering about this topic as I compared my roasts (Gene Cafe) against a local roaster, so this was super timely for me. Their roast looked much more even, but I actually preferred my coffee’s flavor (SM Kenya Kiambu AB - maybe my beans are better 😊). But I noticed the brewing process seemed more predictable on the local roaster’s beans - a very even drip that didn’t risk stalling on Chemex at the same grind setting (Ode grinder with v2 burrs used for both coffees). Can evenness of roast manifest in how the coffee grinds? Or again maybe it’s just the beans, but this held true for a couple of varietals from this roaster.
I’m definitely going to try the “eat the quaker” technique!
It makes sense that it would have an impact, but I wonder if it's one you could taste. A Gene cafe will roast more in the "air roast" vein meaning more bean expansion during roast. I think that could matter.
Thank you for sharing your knowledge! I am having the same issue with uneveness using a home air roaster. However, this uneveness is much less when I roast Indonesian Jambo Gayo beans. I wonder why that is? Much higher unevenness with Ethiopian, and other anaerobic processed beans when doing light roasts. Taste I think is still not bad but just don't know if it can be better.
Sumata vs Ethiopia might have very different moisture content. We measure some Indonesian at 11 to 11.5% and it's not uncommon to have some Ethiopia land at 9% moisture. Quite dry but cupping great. Moisture will impact heat transfer a lot.
@@SweetMariasCoffee thank you for your reply. Yes, most Indonesian beans are quite high in moisture. I had tried some that are 13.1%. Not sure if wet hulling also contributes to higher moisture content. The Jambo beans that I got has quite a low moisture content at 9.8% compared to other Indonesian beans and its natural processed which seems to be less common for Indonesia.
how did u remove chaff from the ground. beans? 🤩
A lot of the chaff will fall off naturally during roasting, but we also use external cooling trays which can help with chaff separation.
Is there a way to measure astrigency? If so then brew up a pot of all quakers and measure it, then count how many coffee seeds in your cup/pot of coffee.
I wish there was! It's a sensation, so I don't know of one.I bought a bag of powdered tannin (tannins like the bitterness in tea) and wow, that was the ultimate astringency. So you can reproduce the effect with compounds like that... -T
I found washed beans to be roasted evenly and aesthetically pleasing to look at. However, the flavor is not as complex as natural beans where when it gets roasted, it always looks uneven but flavor wise, it is more complex and has layers of nuances and depths! (ex natural organic Yirgacheffe). It’s 3 times more expensive than the washed Yirgacheffe!!!
In short: washed beans are more beautiful looking but tasted less complex and whereas the natural organic beans are roasted ugly but tasted extremely good with depths!
Would like to know what score you would give on a non-Quaker bean from that same roast after munching as you have done with the Quakers? I assume higher than the cupping score that likely included Quakers?
Yup, much higher.
In the epilog there I show a COE natural gesha that I scored 87.5 for the cup where I cupped out all the quakers, 85 for the semi-quaker dosed cup, and 83 for the cup the I weighted with the quakers. The good cup had the best clarity of sweetness, and quakers really muddy up the impression of clean sweetness... so that sort of shows the impact of quakers...
The guy cares more about his coffee than his hair. He got his priorities straight.
thanks? ha ha. My hair usually has saltwater in it so that's my excuse. surfing
"...which is a mixed bag."
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