Advice on High heat & drop temp

[bamabeaner]

I am somewhat unsure of some roasting terminology and need some advice. I have often read that certain bean types require different heating profiles. When I hear "high initial heat" say for a Yirgacheffe, does it mean a higher drop temp or more gas during the initial phase of roasting? I would add the same question for "moderate heat throughout"? If I keep my drop temp the same and increase the gas, then I get to first crack too soon, and ultimately get to my finish temps too soon. I am of the opinion that I need to get to FC in the 9:30-10:30 range and finish temp about 3 minutes later. I would appreciate some feedback on this issue.

Also, when do you start the timer? Once the beans have all entered the drum or when you first start dropping them in from the hopper?

Thanks,

Bamabeaner

 

[Hankua]

Bam, you need to give some details like what kind of roaster, drop temp, 1c temp, 2c temp, and the @ times you get to drying, 1c, etc. so the other forum members can make suggestions.

 

[bamabeaner]

I am roasting on an Ambex YM-2. I have been varying my drop temp between 320-380*. I am reaching the turning point at 1:30 min at 150*. I then climb back to And reach FC beginning around 375-380* at 9:30-10:30 min and dropping at 12:30-13:30 min at 415-435*. I don't take it to 2C very often. I am wanting to understand if initial high heat should be accomplished from a higher drop temp or more gas through the drying phase.

 

[eldub]

I think going down to 150* might be dropping it too far down. Especially if you are finishing the roasts in 13 minutes. It sounds like you should maybe raise the drop temp, at least on your initial batch roasted for the day. I'd also consider giving it more gas during the drying process. You could also decrease the gas when you reach first crack to slow the process in that crucial phase.

I shoot for a 15 minute roast on our USRC unit.

 

[CoffeeJunky]

I think going down to 150* might be dropping it too far down. Especially if you are finishing the roasts in 13 minutes. It sounds like you should maybe raise the drop temp, at least on your initial batch roasted for the day. I'd also consider giving it more gas during the drying process. You could also decrease the gas when you reach first crack to slow the process in that crucial phase.

I shoot for a 15 minute roast on our USRC unit.

Very informative...

Thanks

 

[eldub]

Thanks, coffeejunky.

Also..... it appears you are raising your temps an average of 26.5*/min. On our machine we shoot for keeping it at 20*/minute or less. (That translates to a climb of 1*/three seconds.) As first crack begins, I like to slow the process down further.

 

[bamabeaner]

Thanks for the feedback Eldub. If I increase the gas and drop temp, isn't that going to get me to FC sooner? Then my time from FC to drop is going to be upwards of 6 minutes. Is that what I am looking for? Also, do you start your time clock as soon as the beans enter the drum or not until all are in the drum?

 

[expat]

Start timing when you open the chute to put the beans in the drum, or once they are all in. It really doesn't matter as that's just a few seconds when the beans are cold. The place where seconds count is at the end of the roast with a few seconds one way or another being able to make quite a difference in your roast results.

Our standard drop temperature is 175C (350F) and we're shooting for 17 to 22 minute roasts depending on batch size and bean type.

Also for us we do keep track of the time to FC, SC, etc., but The Lovely & Talented Roast Mistress is primarily roasting to taste and smell, with appearance coming next and the time a distant last. Each bean is different. Sumatra roasts (for us at least) lots longer than Ethiopian or Colombian. It is a harder bean and takes longer to cook. A 23 minute roast isn't unusual, dropping the finished beans just as second crack starts to take off. All roasters are different, we have a cast iron drum and it takes longer to heat than steel, so that's a factor but six minutes to first crack is (again, for us) way too fast. A 13 minute roast, unless we're roasting 3kg in our 10kg roaster is way too fast. So there are a lot of variables.

For instance you've got a 2 kilo roaster but are you roasting 2 kilos? If you're sample roasting say, 500g, then the roasting time will be a lot different than if you quadrupled the volume.

 

[Razzo]

Bamabeaner;

What amount in pounds of coffee are you dropping? This will have a large impact on your roast profile. I roast on a YM-2 and typically drop 4.5 pounds with the burners at 100%. I reach 300F in about 7 minutes, throttle the gas back to about 50% at this time, 1st crack at 375F in 11 miuntes and typically finish the roast up between 14-16 minutes.

Razzo

 

[eldub]

Thanks for the feedback Eldub. If I increase the gas and drop temp, isn't that going to get me to FC sooner? Then my time from FC to drop is going to be upwards of 6 minutes. Is that what I am looking for? Also, do you start your time clock as soon as the beans enter the drum or not until all are in the drum?

I'm saying you should consider raising the drop temps/gas to insure your bean temp goes down to around 230* instead of all the way down to 150*.

On the other hand, I think you are giving it too much gas during the roasting process if you are making it from 150* to finish in 12-13 minutes.

So my advice would be to bottom out at around 230* and then to raise the temps no more than 20*/minute until reaching first crack and then cut back on the gas from there to coast to finish.

Btw, Razzo's advice sounds spot on to me.

 

[HillofBeans]

Hi guys i just started commercial roasting in august. I have been adjusting gas to get ramp temps as follows

9lbs in a 5kilo machine
Drop temp 325*F gas set like at 80% to achieve
30 to 40 degrees per minute until 300F degree bean temp

lower gas to 50% (just before 300degrees F) to achieve
16 to 20 degrees per minute from 300F bean temp to First Crack

lower gas to a dribble during FC (like 372F to 395F approx.)

Then raise gas to 20% to achieve

8 degrees per minute until Final Drop at between 412F to 420F- which is at about 15- 16 minutes
i read this somewhere love my coffee and am afraid to change too much from there.
One thing id like to try is lowering the heat a lot more at the drying stage. But that would change the whole profile so much i get queazy thinking about it
Any thoughts- opinions -criticisms?

 

[eldub]

Hill: Are you seeing any pitting of the surface of the beans post roast?

To me, your drop temp is too low. If you increase the drop temp you could slow the rise in temps during the drying process.

Btw, how far down are you allowing the temps to drop after charging the barrel with beans? (I shoot for 230* or so.)

 

[HillofBeans]

Thanks for the reply Your right that was a typo i load the Beans at 425F read from the watlo i set it for 450m let it warm up click on and off and load when the gas is cycled on -the environment thermometer reads like 38-390F

Im at like 80% because at full gas my beans seem scortched (spots of real dark color on the beans and kinda burnt smell)

I dont understand this Question
Btw, how far down are you allowing the temps to drop after charging the barrel with beans? (I shoot for 230* or so.)

 

[eldub]

When you add the beans to the barrel at the beginning of the roast, how far down does the bean temp drop to before heading back up?

 

[HillofBeans]

spoke to Paul from Ambex he suggested not letting my drum get to hot to try less time warming up before roasting and if i still see scorching I should lower the burners so they are not so close to the drum- I do like my coffee but always looking for more flexibility and control- I'm told I should be able to start my roast with full gas pressure