Very little CO2 released by home roasts

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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Mohammad
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#1: Post by Mohammad »

Hello, here's a weird one I've never read about before :)

I've suspected it for a while but only tested it recently. My home roasts degas very little compared to the US artisan roasts I was able to get my hands on and test.

To visualize the difference, in 3-4 days the artisan roasted beans would fill like a 32oz bottle with gas while the same amount of beans from my roasts would only fill a 4oz cup max. Testing was done with sealed food saver bags, not fully vacuumed.

All origins I tested (Brazil to FC+, Sidama to C+, Panama to FC, Sumatra to FC) exhibited the same behavior. I tried varying the drying time from 4:00 to 8:00 minutes with no perceivable change in the amount of gas released. I left some bags sealed for 8 days and got the same result of slowwwwwww degassing, no big bag puff in the foreseeable future. I have one still sealed.

My roasts tasted great, though they require a longer rest. All this done on fresh green beans from Sweet Maria's & GCBC, roasted on my modded Hottop, with profiles like drying 4:00-8:00/ramp 3:30-5:00/ finish 2:30-4:00. My ET never drops and my BT never stalls.

Why is this happening? Can any one crack this one?

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dustin360
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#2: Post by dustin360 »

Isn't this a positive thing? Like your roasts are aging slower than other ones? Or do you think there is actually less gas in your roasts?

Is there cracking at the tips of your beans?

(also why is it important to you that the et never falls?)

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saoye
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#3: Post by saoye »

Can also be a result of how you roast, the depth etc. I believe lighter roasts will tend to emit less CO2 in comparison to a much darker roast.

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Mohammad (original poster)
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#4: Post by Mohammad (original poster) »

Does my original post above need some clarification? If it is somewhat vague, someone please let me know.

dustin360 wrote:.. positive thing? .... cracking at the tips of your beans? ... why is it important et never falls?)
Pros/cons debatable, but now I just want to understand what's the reason my roasts are not like everybody else. I checked 6 roasts, no tip cracking except for the Sumatra. ET never falls because I understood that flattens a roast? You think it is relevant to the slow degassing?


saoye, please check my OP, I mention the beans and roast levels. So, no, it's not that.

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farmroast
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#5: Post by farmroast »

As Dustin touched on, try also monitoring the aging and oils coming to the surface. It might add more info. Surface treatment from heat application both type and amount are generally the biggest effect variables. Conduction as minimal as it is (from drum and from bean mass) even in a commercial roaster, I tend to think is still generally higher than many of the roasters we use.
LMWDP #167 "with coffee we create with wine we celebrate"

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Mohammad (original poster)
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#6: Post by Mohammad (original poster) »

Ed, my roasts tend to age extremely slowly. I have an earlier Sidama City+ roast that is now two weeks old and is still not rested enough for espresso. Even at a fine grind and high extraction temperature, it reeks of unrested gas, maybe in a week it will start to taste balanced. But it is roasted light and it is a Sidama. On the other side, I roasted a Brazil to FC/FC+ that was ready by day 8 and continued to pull beautifully on day 14 with no sign of age, except a lot of surface oil.

Oils on my roasts do come out depending on degree, origin and age. The darker roasts start showing an oil shine by around day 6. The lighter ones would go to week 2 before some very, very, few spots show up on the surface.

Does that say something useful?

On conduction, I totally agree but also have a comment. Yes the perforated drum and fan use will probably mean more IR and convection heating, but I don't see home roasters reporting rest days like mine although many use air roaster, Hottops, behmores.

Another thing I noticed with my roasts is they don't puff much, i.e. they don't go double in size after first crack. They do expand but not as much as I have seen from artisan roasters. But I can't be very exact about this and I would hate to misguide this thread by over stressing this point because I did not measure the sizes so I'm only guesstimating. One thing is for sure, going into 1st crack, i try to keep ET no more than 35 degrees Fahrenheit above BT to avoid ashiness, and I often manage to stay within a 25 degrees delta. I understand this affects bean expansion.

Anything else I missed?

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yakster
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#7: Post by yakster »

It would be interesting to measure the weight loss of the coffee before and after roasting, especially since you mentioned that your coffee is not increasing that much in size during the roasting process.
-Chris

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