RoR

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Postby dhubertus » Thu Apr 16, 2015 12:56 pm

Newbie here. May as well declare such as some things become self evident in short order. I'm looking for opinions on Rates Of Rise for the different phases and please correct me if I have mis-stated the phase temps:

1.) RoR for "Drying" phase (bean turn around 175F to end of drying around 290F?) i.e. if turn @ 1:30 and dry @ 5:00 the RoR is a non-linear 115F/3.5 min = 32d/m or 16d/30 sec.
2.) RoR for "Middle" phase (290F to FC/380F)
3.) RoR for "Development" phase (FC to drop)

I'm trying to lay out a realistic curve and realizing it transitions from slower to faster to slower and would appreciate thoughts as to "approximate" average degrees/30 second increments within a phase. I also understand the charge temp, quantity and drop temp all need to be factored in but trying to get a handle on how fast the different phases are in relation to the overall roast.

Apologize in advance if this is a novice question and truly appreciate your feedback.
Dave
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Postby etanlawok » Fri Jun 12, 2015 7:28 am

I'd love to be able to post a response but I am new as well. I feel like I could speak to it in some way but don't want to distribute misinformation.
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Postby dhubertus » Sat Jun 13, 2015 11:53 am

We're purchasing an existing roaster and he appears to roast everything to the same profile which doesn't make sense. Just finished Rob Hoos book on manipulating the flavor profile in the different roasting phases and found it a great read. My only disappointment is it's only 58 pages and because he was explaining things in a way that made so much sense, I was left wanting more! What kind fo roaster do you use? Ours is a Diedrich IR-7 so because of the nature of the beast, I find the need to anticipate ramping up a minute ahead. Also finding charge temps may need to be higher than the 350-375 range for 10 lb. batches. That being said, I do love the process.
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Postby Jamestooill » Sat Jul 18, 2015 12:57 pm

Dave,

We use RoR quite a lot. Luckily Cropster does all the math for us.

All numbers in degrees farenheit per 30 seconds.

In a typical profile we will see the RoR peak at around 18-22 with softer coffees at the lower end and harder on the higher.
That will fall constantly after the peak at around 3:15, falling faster at first and then gradually decreasing in ascent until the end of the roast. At first crack it will not speed up at all and is likely to be between 12 and 8 degrees(higher numbers for harder seeds) and by the end of the roast it's approaching 3 degrees every 30 seconds.

Hope that helps.
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Postby dhubertus » Sat Jul 18, 2015 2:24 pm

Thanks James. When I plot that on a Yirgacheffe we charge at 380, has a 90 second TP at 170, and we drop at 402, it looks aggressive compared to what we're currently playing with resulting in a little over a 13 minute roast. What area would you concentrate on to give more body? Or, conversely if we wanted to accentuate the citrus/blueberry notes?

Thanks for your comments, they are appreciated.

Dave
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Postby Jamestooill » Sun Jul 19, 2015 5:33 am

Dave,

You're right to notice that it's a little aggressive. Recipes like this for hard beans are closer to 10-10:45 total roast time. But that definitely depends on your roaster and batch-size/drum/fan speed.

For me, all the profile shaping (within reason) in the world won't have the same effect as just increasing or decreasing the level of roast. So any changes to the profile need to be in context of a determined roast degree (and if we're being humble, this roast degree is as much determined by our customers/co-workers and market expectations as by anything else).

That said here's my experience/dogmatic approach:

citric acidity is increased by higher RoR peak at beginning, conversely overly citric coffees can benefit from lower RoR peak that allow more perception of grapey/berry/apply types of acidity.
tinny acidity that falls flat when it cools is a delta point and a not RoR problem.
underdeveloped savoriness can decreased by a faster RoR into and a slower exit out of 1st
Any cereal-like qualities can be fixed by a slower RoR into 1st
Under-soluble grassy coffees with desired roast characteristic may need more sustained high RoR for first third of roast.
As for developing body, I just focus on balancing the coffee across the palate at set cupping parameters. If the customer wants the coffee to be heavier at that point I'd say just use more coffee when you brew.

Hope that helps.
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Postby dhubertus » Sun Jul 19, 2015 1:07 pm

Thanks for your explanation James. I see you've been at it far longer than I so pardon the questions.

"citric acidity is increased by higher RoR peak at beginning, conversely overly citric coffees can benefit from lower RoR peak that allow more perception of grapey/berry/apply types of acidity."
Higher RoR in the drying phase = shorter overall roast = accentuated acidity. Do you find large differences depending on where you peak the RoR prior to 1C?

"tinny acidity that falls flat when it cools is a delta point and a not RoR problem."
Sorry...please explain.

"underdeveloped savoriness can [be?] decreased by a faster RoR into and a slower exit out of 1st"
For instance RoR going into 1C might be around 8-10 per 30 seconds whereas between 1C and drop averages 6. Do you have a % of time of the overall roast you like to spend between 1C and drop?

Thanks for taking your time to explain, it is appreciated.
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Postby Jamestooill » Thu Jul 23, 2015 2:05 pm

Dave,
No need to apologize for being newer. Sometimes I think the longer you roast the harder it can be to learn new ways to think about roasting.

That equation is exactly what I'm saying. Though of course it's good to note that I'm not always trying to accentuate acidity, and sometimes I use this rule to actually lower the perceived acidity. And in my roaster it's very difficult to peak the rate of rise any where but towards the beginning of the roast. And as Rob Hoos points to in his book we do often find better caramelly flavors in roasts that do not speed from yellow to 1st crack too quickly.

"tinny' is probably an idiosyncratic way of saying this so I apologize. Sometimes when we cup the flavors in the hot cup will be more acidic than expected, with less supporting sweetness and depth. When these cups cool sometimes the acidity will be dramatically reduced and sweetness will be low. In this specific case with both higher than expected acidity when hot and lower than expected acidity and sweetness when cool than we will either lower the starting temperature or gas settings to make the bean temperature probe fall to a lower temperature before it starts rising.

Yes. Pretty much all of my roasts spend between 20% and 23% of their total roast time after first crack.

It may have been obvious, but it should be said that the Scott Rao book on roasting was very influential for me.
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Postby EdBourgeois » Sun Jul 26, 2015 9:11 am

The idea behind RoR gives the Roaster a tool to monitor and make rather small specific timely tweaks during a roast with then adequate data to compare to cupping results. This gives a roaster the opportunity to refine their own resulting cup preferences. You can use general thoughts of what happens with faster/slower RoR during various segments of the roast as well as environmental temps/maximum environmental, batch size considerations, effects of air flow with specific roaster design etc. But, you will do much better learning by systematic trial and error and good cupping for some time than starting out by seeking others profiles and trying to translate. Same as always, developing an understanding of your roaster and controlling it is super important too.
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