Coffee is super bitter

Hi guys,
i just received my bullet yesterday and already got a few roast on it.

Here are 2 examples:
https://roast.world/@stefan.duemmlingugoe/roasts/xTbOfHdb8TGHFxuvwdpDB
https://roast.world/@stefan.duemmlingugoe/roasts/hMyNqef-5LpofFSQk5MGZ

I cupped those, and they taste disgustingly bitter, harsh bitterness - really bad. The ones from yesterday do so too.

Anyone having some tips or suggestions to get rid of the bitterness?

Thanks in advance,

Stefan

Hopefully you are referring to roasts that are post-seasoning of the drum.

Yeah, i seasoned the drum with 6kg´s

Just venturing a guess here…I’m still a relative newbie on the Bullet (@bradm and @bab and a couple others might have better suggestions), but my guess is you’re venturing into or at 2C thus the bitterness. Personally I find 2C to be bitter no matter which bean.

Stefan I am in similar position, how long did you allow between seasoning and drinkable roasts?

I’ve never roasted Monsooned Malabar so take my comments with a grain of salt! Just a couple things that come to mind-

Looking at the chart I see the beans were ejected at about DT = 413°F (the IBTS) which is well short of 2C. I expect 2C to start somewhere above about 440-445°F. In fact this roast is probably short of completion of 1C. So there’s a chance the roast didn’t hit the minimum time for a completed roast (anytime after completion of 1C for a light/City roast). It’s a shame too as the chart otherwise looks great.

The 2nd thing that comes to mind is bitterness from over extraction during brewing. That can happen a couple ways depending on brew method but the one that’s easiest to do is to grind too fine. Any chance the grinder was set too fine? or a filter system set to a low flow rate? or a Clever Coffee Dripper left closed too long?

If you’re convinced the roast finished 1C then there could be a calibration error in IBTS caused by a dirty lens on the IR sensor of the IBTS. It takes several passes with something like a Q-Tip wetted with alcohol to clean first the view port of the sensor (the black rubber portion; angled up at about 45°) and then second the lens of the sensor. It may take several passes to get the lens clean because whatever it is that gets in the way doesn’t want to come off. To make it more of a challenge, the contaminant does not show up on the cotton of the swab so you can’t judge progress.

To be honest the temperature difference between BT and DT (IBTS) in your roast is great enough in the early stages of the roast (just before yellow point) that I wouldn’t suspect a dirty sensor lens. If I see > 40 F° difference I am inclined to think the sensor is still ok.

Bruce

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@bab Thanks 4 the answere! In fact

The 2nd thing that comes to mind is bitterness from over extraction during brewing. That can happen a couple ways depending on brew method but the one that’s easiest to do is to grind too fine. Any chance the grinder was set too fine? or a filter system set to a low flow rate? or a Clever Coffee Dripper left closed too long?

Adjusting the grind kind of made it better a bit. Still there is a bitterness remaining in both these rosts i never tasted before. My last guess is that the beans kind of need some more time to rest - and i am simply not able to brew a good cup of coffee with coffee this fresh :wink: . Brewing is kind of a sparkeling event cause of all the CO2 trapped inside.

Looking at the chart I see the beans were ejected at about DT = 413°F (the IBTS) which is well short of 2C. I expect 2C to start somewhere above about 440-445°F. In fact this roast is probably short of completion of 1C. So there’s a chance the roast didn’t hit the minimum time for a completed roast (anytime after completion of 1C for a light/City roast). It’s a shame too as the chart otherwise looks great.

The thing is, the coffee should taste in this case more acidic, vegetable, unripped fruits, grassy etc. and thats not the case. I wish you could taste a cup :slight_smile: .

@Snidely_Whiplash I didnt w8 at all. Straight after seasoning i started roasting. But its clearly not drinkable (yet).

@blacklabs Thanks for the answere! I think its not the 2cond crack bitterness though. Its really hard to describe. Just imagine you drink a cup and you feel like eating a centershock. Just bad.

I think i just w8 two or three days and try again and keep you guys informed.

Thanks for your time and your tips!

Stefan

:blush: I should have looked carefully at your temps! Of course @bab is correct you were barely at 1C. I roasted the Monsoon once at a Probat roasting workshop years ago and I pulled out my notes. Your temps and numbers are similar to what we did for that roast so I’m not sure why yours is bitter because I can recall the instructor telling us that we did a really good job with the Monsoon when he cupped it the day after and bagged it for us to take home.

@bab, @blacklabs the Honduras was underdevelopement 4 sure. Streching out the time span between yellow and FC aswell as spending out the timespan of developement time sealed the deal.

Thanks again to all the answeres!

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Those both look like reasonable roasts, so my first guess would also be needs more rest. Hopefully they’ll smooth out dramatically about a week post-roast. I like to keep 'em in a closed container with 1-way valve during that time, resisting the urge to open it and let in oxygen. I’d also second @bab idea about grinding more coarsely, if you’re brewing not pulling shots.

No experience with the Malabar, but others mention preferring dark roasts into SC.

If the bitterness is smoky or ashy, more airflow late in the roast might help too. I’ve been a big fan of using F2 and F3 for 325g batches, but in my limited experience recently the larger 500g+ batches are MUCH more smoky and seem to need quite a bit more fan (and ventilation, sorry @blacklabs for not seeing that one coming) to avoid smoky ashy flavors.

Looks like you did a few more Honduras roasts with varying profiles, including more fan. Please post how those end up tasting in comparison.

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@bradm Thanks for the answere.

Looks like you did a few more Honduras roasts with varying profiles, including more fan. Please post how those end up tasting in comparison.

Low fan settings are a good point - thanks for the hint.

It is tasting far better. I just ignored nice curves and stuff and tryed to hit the right color and length of the phases. I aimed for a longer maillard phase for more body and longer developement and darker color to support the chocolate style of the coffee itself. Anyways, i think i took it to far for #5 and especially #6.

Honduras # 5 is the best so far. The cup got a little sweetness and acidity left, but its not much. Today i am gonna do one more roast with the Honduras with a little less color and developement time. I am aiming at 5.30 yellow, 9:15 - 9:30 FC, Drop after 2:45 - 3:00 Dev-Time at around 212 C. My goal is to get a bit of sweetness and acidity back, since the cup is pretty dull.

This is good experimenting especially since you’re using the same beans for all of these then you can compare them.

Your #5 you took it to F7 and dropped down to P4 when you hit 2C. I suspect that may be what’s getting you the little sweetness still even for a 2C roast. You might consider a similar profile and adjust when you start to drop temp and increase air.

As for dull cup, I also find giving the beans a rest for a week seems to give me a better cup experience (definitely true with Yemen beans).

@bradm - I haven’t set off the smoke alarm since the super dark seasoning roasts and haven’t had to hit the highest settings on my vent hood … so far so good :wink:

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@blacklabs , @bradm, @bab, @Snidely_Whiplash

Roast #7 is really good now. Balanced Cup. Thanks again for your efforts - you really helped me!

Greetings,

Stefan

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Nice! @stefan.duemmlingugoe the thing that jumped out at me most with #7 is you have a lower charge temp than your other ones. I’ve not roasted more than 500g so I was thinking you went higher because of larger batch size, but maybe that was also contributing to the char/bitter because it was too hot. I’ve mostly stuck with 392F as charge temp, but I may go to 400F (or whatever is next up from 392F) next time so that my 500g roasts don’t take so long. If I venture into the 666g batches I may use your #7 profile as a reference :slight_smile: @bradm’s profiles at 325g is what I started with for both my roasting at that 325g batch size and 500g size. FWIW - when I looked back to my notes from the Probat workshop our charge temps were consistent at 400-410F for the 6kg batch in a 12kg gas roaster.

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Ok, I have progressed as well but note I am doing lighter roasts, (following std recipe from the Manual mostly, to build on) dropping just after FC, going nowhere near 2C. Using a Brazil Monte Cristo, 350g batches and 13-16 C ambient temp.

My R2 was particularly bitter in first tasting but has mellowed a bit after being in the bag a few days.
R7 was a very tasty cold brew last night after roasting yesterday, so interested to see how it shapes up with a few more days in the bag.
Any feedback welcome.
R3
R7

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Hi @stefan.duemmlingugoe

I see you’ve done a lot of roasting since you started this thread. How has the coffee been cupping? What kind of brew methods are you using when serving? I’m really keen on hearing some of your results, flavour and aroma notes and comparing them to the roast profile.

Cheers!

@david.nash.aushr2

Sorry for the late reply. Most of my roasts tasted somewhat okay - little to none of them are great. I think i found out the reason today.

I serve my coffee most of the time with a portafilter mixed with milk. The rest is served with chemex or aeropress. I have and especially had a problem with proper development of the inner bean resulting in sour espressos (extraction checked with refractometer). Roasting darker is masking the problem, especially when you drink it with milk. Grassy and bad developed filter coffee is served to the bin.

Anyways, todays roasts are just fine. Right now i think there are two possible reasons i didnt have had the problem today.

  1. Give the Roast more time to develop pre crack (i am aiming for 10 minutes, didn´t achieve it yet :wink: )
  2. Reducing the momentum to enter FC

I will roast a few more tomorrow and keep you guys informed.

Cheers

@david.nash.aushr2 Slowing things down and the momentum change to enter FC (round about 6 ROR) changed things by a mile. My filter roasts now taste really delicious. I switched to Artisan to get rid of the noisy ROR curves in RoasTime - so you sadly cant check curves. This video helped me out a lot for my light roast. Today i am gonna approach Espresso Roasts.