Hi,
I am running into some problems with my roast profile on my Diedrich IR-12. Below are two15# profile roasts that I have completed and am getting a coffee taste with a flat flavor. Any help from you all would be greatly appreciated.


15# Costa

Drop 415 f – gas @ 80%

After 1 min. drop gas to 50%

Bottom out – 167 f

240 f @ 3:75 – 4:00min

280f – 50/50 air

305f @ 6:00min

370f @ 10:30 – Full air

1st crack 382f @ 11:00

Finish temperature 432f – start of second crack (15:20 min)

Roast development 4:20 min.

Coffee is flat w/o flavor


15# Guat

Drop 415f – gas @ 80%

After 1 min drop gas to 50%

Bottom out – 163f

240f @ 4:00 min

280f @ 5.5 – 6:00 min

280f - 50/50 air

305f @ 7:00 min.

370f @ 10:05 min – Full air

1st crack 381f @ 11:00min

Finish temperature 431f – start of second crack (15:42 min)

Roast development 4.42 min

Coffee is flat w/o flavor


15# El Sal

Drop 415f – gas @ 80%

After 1 min drop gas to 50%

Bottom out – 163f

240f @ 4:00 – 4:30 min

280f @ 5.5 min

280f - 50/50 air

305f @ 6:30 - 7:00 min.

370f @ 10:05 min – Full air

1st crack 376f @ 11:00min

Finish temperature 432f – start of second crack – 15:00 min

Roast development 4:00 min.

Coffee is flat w/o flavor

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I am not an expert on Dietrich's, so hopefully someone who roasts on them regularly will chime in, but a couple of thoughts... 

When you say flat w/o flavor, my assumption is immediately that the perceived acids have been reduced too dramatically.  These acids are what make coffee come alive (think about how adding a teaspoon of wine vinegar to marinara before serving makes a boring sauce come alive, or a twist of lime or lemon on Mexican food, for example).  As a roast develops over time, these acids decrease, and seem to drop off very dramatically at the onset 2nd crack and beyond.

I assume you cupped these coffees at a lighter roast degree and found them not to be flat and without flavor, correct?  If not, that would be my first step to evaluate the potential of these coffees.  Next, I would personally try a higher charge temp and manipulate heat/flow in a way to see first crack onset around 10 minutes.  I think your Roast development time is acceptable, but perhaps try dropping 4-5 degrees sooner, just before the onset of 2nd.  Give it a taste and see if there is any marked improvement. 

Would love to hear what you come up with.

Keith

Venia Coffee

Hi Keith,

 

First of all I should let you know that I have been roasting on a small batch Coffee Tech roaster for the past 3 years and have recently purchased a Diedrich IR-12 coffee roaster.

Yes, the coffee lacks acidity and flavour.

 

When we did our cupping we were able to pull some nice floral and fruit tones, so I am not too worried about the quality of the green beans. Here are some of the changes I made to our new profile which allowed us to bring in some fruit tones and more acidity.

 

I lowered my charge temperature to 410f and used 70% gas for the first minute and then moved it to 50%. My thought was the temperature was too hot in the drum and it was possibly scotching my beans. However, I have noticed that people drop their beans at temperatures near or above 420f for SHB. What charge temperature do you use for 15# of coffee? We bottomed out between 159f – 162f.

 

As I moved towards 240f, I tried to keep the temperature rise between 30f - 40f. Once past the 240f mark I lowered the gas and tried to even out the temperature rise so that it was consistent until reaching 330f. It is my understanding that between 240f and 330f is the final drying stage and the temperature should be consistent so that the beans dry properly.

 

I brought 50/50 air in at 270f instead of 280f.

 

30 – 60 seconds before the first crack, I reduced the flame and let the exothermic heat finish off the roast. The new profiles had a 3 minute finish opposed to 4 minutes. Finish temperature was 424f – 427f with the Costa, Guat and El Sal beans.

 

1st crack was between 11:00 – 11:30 min. I know roasters like Probat and Giessen can have quick 1st cracks (ie 10:00 – 10:30 min.), which play well with acidity and the flavor of the coffee. Not sure if these roasters (Probat, Giessen) provide good coffee with a 11:00 - 11:30 1st crack.

 

I did get a much better roast from the Costa, Gaut and El Sal. I would like to try to get more acidity, so was wondering what you or others would suggest.

 

Do you agree that too high of a charge temperature (ie 420f) has an effect on the bean being scotched?

 

What is your average bottom temperature?

 

What roaster are you using?

 

What is an average time for 1st crack using a Diedrich IR-12? 11:11:30 seems long, but I am not sure.

 

I’m sure I will have more questions to follow.

 

Thanks

 

When people say "flat without flavor," it's usually an indication of 'baking' of the coffee, that generally comes from the roast stalling at some point.

Two spots in your last post are potential red flags: "It is my understanding that between 240f and 330f is the final drying stage and the temperature should be consistent so that the beans dry properly" and "30 – 60 seconds before the first crack, I reduced the flame and let the exothermic heat finish off the roast."

I'm not sure what you mean by "consistent." Do you mean flatten-out the temp curve, or keep the rise consistent? If it's the first, that's a mistake.

As for the exothermic stage, reducing the flame a bit is a good idea, but it makes me wonder (again) about what you mean by "finish off the roast." You may be reducing it there too much. You want a nice, healthy and hearty first crack.

FYI: I'm not a roaster... but I pretend a lot. Good luck!

The temperature climb between 240f - 330f is as follows:

  • 4:00 min - temperature 236f – 33f climb
  • 5:00 min - temperature 264 – 28f climb
  • 6:00 min - temperature 286 – 22f climb
  • 7:00 min - temperature 306 – 20f climb
  • 8:00 min - temperature 321 – 15f climb
  • 9:00 min - temperature 339 – 18f climb

 

From my perspective, it is a nice climb and doesn’t appear to be stalling.

 

I also found on my first profile when my coffee was flat, I flew through the first crack. It was my understanding that you want to go through the first crack slowly and continue to coast until you are at your finish temperature.

 

 

 

As you know, comparing roasters and roasting isn't always an apples to apples comparison, especially when comparing roasters with atmospheric burners to infrared burners.
Most Dietrichs are designed to have a constant air flow temperature (around 450f if I recall) no matter the air flow volume. Also, Dietrichs seem to be designed towards using the potential energy stored up in the drum to guide the roast, so quick temperature changes are hard to accomplish and the operatior needs to be thinking two steps ahead...sometimes making changes minutes earlier than atmospheric roasters I am more familiar with.  I wouldn't call either roaster type better, just different, and they each have their own learning curves to use their inherent qualities to produce a great product.

Also, speaking very generally, most florals seem to be volatile and are usually at there best soon after 1st has completed, so your degree of roast may be playing into the loss of florals to some extent.

One way to tell if your charge temp is too high is that you will see "tipping" on the beans.  Pull a handful after the roast is complete and look for more browning on the ends of the bean.  If you notice this, you likely are overheating the drum before dropping.  That said, I think your charge temp seems low, as well as your bottom temp after drop.

I would suggest just choosing one bean for now. Find the degree of roast you want (how dark, and if you are wanting a nice acidity don't go too dark).  Next run 3 different roasts where you drop at the roast degree you first determined.  Aim for 11, 13, and 15 minute roast time on each (for example) and cup them out to see if you find one is closer to the profile you want.  Also, keep records of all your roasts, as it seems you are doing.  Nothing like nailing it on one roast and then forgetting what you did.

Keith
Venia Coffee

Looks like you have an S shaped curve in the middle of the roast which is a "flattening" out of sorts.

From my perspective, the optimum temp rise through the middle of the roast is ~ 20. I think you could try a bit less gas on the front end and look for a more consistent rise throughout the roast.

Cutting gas towards the end of the roast is very common with Diedrich but I don't think you want to see the curve flatten out here either, but it's also easy to have a spike in the last minute if you keep full heat going.

I also alter the drop temp depending on the coffee type, batch size and profile.

Everyone I've talked to using IR-12 has found an optimum batch size for a particular coffee. For me, the max is 22 lb. and that's what all our production roasts are. I roast as little as 6 for special orders and have even gone down to 1 lb. just for fun.

Good luck.

N. Hewitt said:

The temperature climb between 240f - 330f is as follows:

  • 4:00 min - temperature 236f – 33f climb
  • 5:00 min - temperature 264 – 28f climb
  • 6:00 min - temperature 286 – 22f climb
  • 7:00 min - temperature 306 – 20f climb
  • 8:00 min - temperature 321 – 15f climb
  • 9:00 min - temperature 339 – 18f climb

 

From my perspective, it is a nice climb and doesn’t appear to be stalling.

 

I also found on my first profile when my coffee was flat, I flew through the first crack. It was my understanding that you want to go through the first crack slowly and continue to coast until you are at your finish temperature.

 

 

 

Some things to look at:

Bottom out should happen around 90 seconds.

Stay on your temp. after bottoming out instead of reducing temp. which will bring you to 1st crack sooner (around 10 min.)

I would try waiting until 1st crack before increasing airflow to drum.

Try reducing bean dev. time to around 3 to 3.5 min.

How long is it taking to cool down the roast after it hits the cooling bin. The quicker the better. make sure your cooling bin is doing a good job cooling beans down quickly so the roast doesnt have a chance to continue after you dump. just a thought..

 

good luck... please report back.

Nick

 

 

 

I roast on a Deidrich. How much coffee are you roasting per batch? Depending on what you are trying to achieve, you need to find your sweet spot as far as optimal batch size. If you are looking for high notes then your profile is incorrect. I would use your profile if my goal was to mute acidity and flavour.

Her batch size is 15#'s. could you give her an example of what you beleive would help her achieve the vibrancy I beleive she was looking for. of course she will have to tinker given the specific coffee she will be applying it to but at least she would have a starting point to apply the areas you beleive her profile needs adjustments.

thanks.

 

this is why I love this forum.

Hi Keith,

There does not appear to be any sign of tipping on my beans. Your correct in saying that you need to be thinking 2 min ahead.

I am dropping my coffee 3:00 min after the 1st crack starts. I also turn the gas down about 30 sec - 1 min prior to the 1st crack, so that I can have a longer RD (in this case 3:00 min).

Great suggestion on the roast degree!

Thanks

Keith Eckert said:

As you know, comparing roasters and roasting isn't always an apples to apples comparison, especially when comparing roasters with atmospheric burners to infrared burners.
Most Dietrichs are designed to have a constant air flow temperature (around 450f if I recall) no matter the air flow volume. Also, Dietrichs seem to be designed towards using the potential energy stored up in the drum to guide the roast, so quick temperature changes are hard to accomplish and the operatior needs to be thinking two steps ahead...sometimes making changes minutes earlier than atmospheric roasters I am more familiar with.  I wouldn't call either roaster type better, just different, and they each have their own learning curves to use their inherent qualities to produce a great product.

Also, speaking very generally, most florals seem to be volatile and are usually at there best soon after 1st has completed, so your degree of roast may be playing into the loss of florals to some extent.

One way to tell if your charge temp is too high is that you will see "tipping" on the beans.  Pull a handful after the roast is complete and look for more browning on the ends of the bean.  If you notice this, you likely are overheating the drum before dropping.  That said, I think your charge temp seems low, as well as your bottom temp after drop.

I would suggest just choosing one bean for now. Find the degree of roast you want (how dark, and if you are wanting a nice acidity don't go too dark).  Next run 3 different roasts where you drop at the roast degree you first determined.  Aim for 11, 13, and 15 minute roast time on each (for example) and cup them out to see if you find one is closer to the profile you want.  Also, keep records of all your roasts, as it seems you are doing.  Nothing like nailing it on one roast and then forgetting what you did.

Keith
Venia Coffee

Hi David,

Do you keep your gas at a steady pressure? Or, are you moving it up and down trying to keep a steady degree climb?

I find that when I start my climb, the degree in temperature climb is around 33-35f per min and then I need to lower my gas so that it slows down from 4:00 min - 9:00 min. The hard part I am finding is to get a steady climb in temperature through this period of time. Any suggestions?

Thanks



David Myers said:

Looks like you have an S shaped curve in the middle of the roast which is a "flattening" out of sorts.

From my perspective, the optimum temp rise through the middle of the roast is ~ 20. I think you could try a bit less gas on the front end and look for a more consistent rise throughout the roast.

Cutting gas towards the end of the roast is very common with Diedrich but I don't think you want to see the curve flatten out here either, but it's also easy to have a spike in the last minute if you keep full heat going.

I also alter the drop temp depending on the coffee type, batch size and profile.

Everyone I've talked to using IR-12 has found an optimum batch size for a particular coffee. For me, the max is 22 lb. and that's what all our production roasts are. I roast as little as 6 for special orders and have even gone down to 1 lb. just for fun.

Good luck.

N. Hewitt said:

The temperature climb between 240f - 330f is as follows:

  • 4:00 min - temperature 236f – 33f climb
  • 5:00 min - temperature 264 – 28f climb
  • 6:00 min - temperature 286 – 22f climb
  • 7:00 min - temperature 306 – 20f climb
  • 8:00 min - temperature 321 – 15f climb
  • 9:00 min - temperature 339 – 18f climb

 

From my perspective, it is a nice climb and doesn’t appear to be stalling.

 

I also found on my first profile when my coffee was flat, I flew through the first crack. It was my understanding that you want to go through the first crack slowly and continue to coast until you are at your finish temperature.

 

 

 

Hi Nick,

I do bottom out at 90 seconds @ around 163f.

My 1st crack is around 11:00min - 11:30min and then have a 3 min RD time.

It takes about a 2:00 to cool the beans to room temperature.

Thanks



nick placakis said:

Some things to look at:

Bottom out should happen around 90 seconds.

Stay on your temp. after bottoming out instead of reducing temp. which will bring you to 1st crack sooner (around 10 min.)

I would try waiting until 1st crack before increasing airflow to drum.

Try reducing bean dev. time to around 3 to 3.5 min.

How long is it taking to cool down the roast after it hits the cooling bin. The quicker the better. make sure your cooling bin is doing a good job cooling beans down quickly so the roast doesnt have a chance to continue after you dump. just a thought..

 

good luck... please report back.

Nick

 

 

 

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