Getting craters on roasted beans and coffee with no body - please help

[coffeem]

i hav 5 5kilo roaster US Roaster (stainless steel drum) and have started doing sample roasts (1 to 2 lbs). The charge temp i have been using is 340 degrees and roasts for 13.5 minutes. I am getting a lot of craters and coffee body is weak.

i also have run 6 lbs @ a charge temp of 380 degrees with a 14 min roast. coffee taste good but no body at all.

can anyone let me know what i might be doing wrong?

PS - samples were run using colombian excelso.

thanks!

 

[sae]

"craters" tells me you're hitting second crack hard and no body tells me that you're roasting very dark. Some more info and maybe some pictures might help.

 

[eldub]

What were your final bean temps?

How far did the temps drop after charging the barrel with beans?

How hot did the air temps get in the roaster?

It sounds like you brought the temp of the beans up too quickly. As for the lack of body, I really don't understand what that means. Over roasted beans are sometimes described as being thin and lacking body.

 

[coffeem]

lets adrees the 1 - 2 lb test 1st then address the 6 lb load afterwards

1) for 1 - 2 lb roast temp dropped to about 245 to 246 after charging barrel with beans
2) air temp is well over 400 even getting to 500
3) FC was reached 348 to 357 degrees
4) i have been following this rule of thumb as far as controlling the gas knob: after 250 degrees temp should rise 10 deg every 30 sec up until 1s crack then it should be 10 degrees every 1 min.

am not roasting the beans dark. drop temp ranges b/w 403 and 408 degrees.

 

[eldub]

Your roaster's air temp should never have to rise above 425*. Even when I roast dark, (final bean temp of 465*) the roaster's air temps never go above 425*.

You are raising the bean temp way too quickly, imo. A ten degree rise/minute is a good rate to shoot for until first crack. Then you want to slow down the process to around 15*/minute or less. (One degree per four seconds.) You should be aiming for a 15 minute roast.

403-408* is much lower than our lightest roast. I'm taking our Colombian beans to 445*. Our Yirgecheffe goes to 425*.

Btw, I have to question the accuracy of your roaster's bean temp gauge. First crack never happens in our roaster until around 380*. The only other thing I can think of to make the crack happen that soon would maybe be due to the fact that your roaster is getting up around 500* air temps.

 

[coffeem]

thanks for your quick responses. any idea of what could be causing the air temp to rise to the levels that it is rising to? could it be an airflow issue? i am told that the damper is in open position when the handle (with knob at end) is pointing back to exhaust fan (parallel to me if i was facing the roaster standing at the controls).

yes and i too was concerned thast FC was happening so early in the roast.

 

[coffeem]

i just roasted a 1 pound batch (costa rican) using 10* increments every one minut and then 15* every one minute at 1st crack. still was only able to get to 380* and over 15 minutes to get to that point (so I dumped the beans). i did charge the beans into the drum at 300*.

meanwhile air temp showed close to 500 and bean temp 380 (and they were not dark at all.
didnt get any craters...but brewed a sample pot and as you can imagine it was awful. dont really know what to do at this point. i am pretty frustrated.

 

[eldub]

Relax. You will be fine.

The air flow is at full open when the lever is pointed toward the back of the machine, as you explained above.

You should concentrate more on the final temp of the bean mass and less on the time to get there. The finishing temp is the most important aspect, imo. Btw, we take our costa rican to 432*.

How much gas are you applying during the process?

Here's a general guide to follow....

Roast smaller batches before larger. The first batch of the day will allow the most control over a small batch size because the roaster is still relatively cool. Little batches are the most difficult to control, imo. They want to go fast when your roaster is really warmed up.

Charge the roaster and look to bottom out in the 190-220* range. (Bean mass temp.) On my roaster this usually takes between 2:00 and 2:45. The bean mass temp will usually start to rise when the air temps reach about 300*. On my roaster, I apply about 2" of gas at this point. My goal is to get the air temps up to 350* by the time the bean mass reaches 300*. When the beans reach 300* I apply a little more gas and attempt to get the air temp up to 400* just about when the bean mass reaches 350*. When your roaster air temps get to 410* you can start cutting back on the gas. Keep lowering the gas until air temp stops climbing. (But don't let the air temp fall below 400*.) Your bean temps should rise a bit slower at this point. If I'm roasting a light batch, I like to gain control/slow the rise in bean mass temps BEFORE first crack is reached. With a very small batch, you might be applying close to no gas after first crack to keep the air temp at 400* and the bean temps climbing at a proper rate.

Time is less important than final bean temp. Some of my roasts take 13 minutes, some take 17. Shoot for 15.

 

[CoffeeJunky]

very interesting. Your bean temp has to be over 400 degree to be able to have develop the taste. Did you try asking the manufactures about the problem you are having? Eldub has the roaster that was made by the same company. Maybe it would be wise to get in touch with him directly.

 

[eldub]

One more thing before I head into work...

The next time you fire up your roaster, check out the flame level. (I assume the roaster is gas?) There is a little square door above the control panel that you can open to see the flame. You should be able to adjust the gas down to the point where every single jet is a tiny point of flame. If you increase the gas a bit the flame should rise and soon become a swirling mass of fire. The gas pressure is measured in inches on the gauge. At full open, my gas pressure reads about 2.75".

 

[coffeem]

yes i checked my gas pressur and when i turn mine up full blast the gauge reads 3.5".
still experimenting ..will let you know how thigs are turning out. btw i think i may have met you at SCAA in Boston at the US Roaster booth. Were you there?

my [email protected]

 

[eldub]

You have a lot more top end on the gas pressure than I do. I'm guessing you have been running close to full throttle to reach 500*. I doubt you would ever need to go more than 2.75" to get optimum results.

I'm guessing you met Dan and his nephew in Boston. I'm just a customer of theirs and don't get enough time off yet to attend those events.