Development time as a ratio of roast time by Scott Rao - Page 7

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
fu11c17y
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#61: Post by fu11c17y »

Clint Orchuk wrote:Isn't Marshall saying he's getting great results with his fluid bed roaster by applying the techniques?
He is, with the development ratio. But he is not, with the decreasing RoR in one of Rao's "commandments".

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endlesscycles
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#62: Post by endlesscycles »

I had been applying straight line roasts with 13% development ratio, and getting good coffee. That was before trying a slew of Rao inspired roasts. With these, I'm using a decreasing ROR with 20% development ratio. In tandem, these methods are working well and directly address shortcomings in the cup I had experienced with my previous approach. I prefer the Rao inspired cups; they are fuller, cleaner, and more soluble.
-Marshall Hance
Asheville, NC

fu11c17y
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#63: Post by fu11c17y replying to endlesscycles »

Sorry Marshall for the misunderstanding. As much of a newbie as I am compared to some of the veterans on this forum, I have been roasting with the straight line approach all along, until a few months ago. Constant RoR by adding more and more heat, until a target ET is reached which, from then on, is held more or less constant until FC, then let roll downhill till drop. The developing time would more or less fall within the Rao range.

I began to immerse myself in the Boot (declining RoR) approach a few months ago and try to get great results with it, with the intention to cup side-by-side blindly with my earlier approach.

I still havent spent enough time on this approach to draw anything conclusive yet. But I think you can get great cups with either of these approaches for most beans, with a few exceptions... well, at least the sweet spot becomes much smaller with these beans when you use one approach over another. For example, I had problem with a few washed Yirga using the straight-line approach (but not with the washed Yirga from Roastmasters), and I had problem with an old batch of the Rwanda Karongi Gitesi using the Boot/Rao approach. It could just be me and/or my roaster though.

In any case I have to say that with the flatline RoR approach (Marshall should chime in on this too), there's this inherent, latent sweetness that is unmatched. This could be what James Hoffman once blogged (http://www.jimseven.com/2010/08/06/suga ... versation/) about a few years ago (sorry, I'm a big fan of his blog), in which he discussed with Deaton Pigot about conversion from complex long-chained carbohydrates to simple sugars in the roasting process. The flip side is I found that this approach gives you many more ways to fail. For example, if the RoR is too fast or too slow on the ramp, it would give you this off taste that's either earthy or slightly bitter. Shelf life is also compromised with a fast ramp.

On the other hand, with the declining RoR approach, it yields a coffee, relatively, with better aroma, body, integrated sweetness, overall a smoother cup, and I believe better shelf-life, when compared to the same bean roasted with the flatline approach. I also find this approach to be much easier to get a good cup. Just follow a few "rule of thumbs", and it would turn out at least pretty good, although this could be attributed with me being more experienced at this point with cupping and roasting, and in general knowing "what knobs to turn" to change certain characteristics in a cup. Again I have not had as much experience with this approach, but that's what I have observed so far.

fu11c17y
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#64: Post by fu11c17y »

It doesnt hurt to cite this reference. My Colombia was roasted with a flatline approach. Notice Ken Davids mentioned "bitter". While well balanced in this roast, it was one of the balancing act involved roasting with this approach, making sure there was not too much bitters in the cup.

http://www.coffeereview.com/home-roaste ... -skillets/

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boar_d_laze
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#65: Post by boar_d_laze »

Clint Orchuk wrote:Isn't Marshall saying he's getting great results with his fluid bed roaster by applying the techniques?
He did. But the outstanding thing about Marshall as an example is that for years he's reported great results NOT using the ratios Rao recommends. Just a week or so ago, Marshall suggested 3, 3, 1 (14.3% Development to Roast ratio) to someone looking to maximize acidity. We can assume that the profiles worked for Marshall in the past, and infer then that the Rao Rule is not necessary for good results in all circumstances.

I think it's great that we're discussing main-stream medium roasts in drum roasters, considering that's what I like to do, but it's important to bear in mind that Scott Rao neither invented nor popularized the Development to Roast ratio change he's suggesting. If I understand what he's reported to have written, he's noticed that they're how most successful roasters do the sorts of roasts Rao likes; which seem to fall somewhere in the medium range. For instance, I'd be willing to bet that over 90% of the roasts which Ken Davids rates at 90+ are roasted in Rao's preferred range.

Regarding declining RoR: It's not that easy to use any sort of reasonably quick Drying interval (whether or not "Drying" is the appropriate name) and increase the RoR through Ramp. So a flat or declining RoR is more or less an inevitable part of (ordinary) drum roasting. (Marshall's suggestion of a double derivative is a nice idea.)

Similarly a Development to Roast ratio which falls outside the norms Rao reports, is unusual in medium roasts (C/C+ - FC/FC+) because that's how much time it takes to put together a controlled Development + Ramp and a Development which goes to the desired finish, without overcranking the roaster. Chris Schooley mentioned controlling Drying and Development in his Stretchin' Out the Roast series of articles he wrote quite a few years ago (which may be accessed here). Note the ratios in Chris's roasts.

It's my impression that although it may not look like it, Jim Schulman is getting at the same sorts of things -- that is, (a) there's nothing new about this stuff and (b) there are ways around Rao's Rules -- in his technical posts.

Regarding a point brought up in another post: Well known, main-stream roasting theorists and commercial roasters like Willem Boot and Mike Perry may not have published "how to" books for home roasters, but their wisdom is available in their classes (including Boot's online class). Costs more, though.

Rich
Drop a nickel in the pot Joe. Takin' it slow. Waiter, waiter, percolator

fu11c17y
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#66: Post by fu11c17y »

boar_d_laze wrote:......Thom Owens mentioned controlling Drying and Development in his Stretchin' Out the Roast series of articles ......
I remember Chris Schooley writing those articles for SM, but I could be wrong, and definitely digressing... 8)

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boar_d_laze
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#67: Post by boar_d_laze »

fu11c17y wrote:I remember Chris Schooley writing those articles for SM
  • Credit where credit is due;
  • Good catch;
  • Thanks for the heads up; and
  • Corrected.
:)
Rich
Drop a nickel in the pot Joe. Takin' it slow. Waiter, waiter, percolator

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another_jim
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#68: Post by another_jim »

endlesscycles wrote:I had been applying straight line roasts with 13% development ratio, and getting good coffee. That was before trying a slew of Rao inspired roasts. With these, I'm using a decreasing ROR with 20% development ratio. In tandem, these methods are working well and directly address shortcomings in the cup I had experienced with my previous approach. I prefer the Rao inspired cups; they are fuller, cleaner, and more soluble.
Let's go back about twenty years, and take a look at what the coffee research journals, roasters like Staub or Boot, and roaster designers like Diedrichs and Sivetz called slow start/fast finish and fast start/slow finish profiles. It will make a refreshingly clear change for the terminologies of RORs and ratios which hide more than they reveal (although in the interests of politeness; I'll restrain myself from calling them obscurantist mystification).

So lets put up a diagram of a classic 8 minute fast start, slow finish Sivetz air roast profile , and a classic 16 minute slow start, fast finish Diedrich drum roast profile ending at the same temperature. For sake of some fun integral geometry, these roasts start at t-16 and t-8, and end at the same time ...



As you can see, the total heat input in these roasts, the areas under the curves, are about the same. The Diedrich's roast spends more time getting its heat at lower temperatures, and less time getting its heat at higher temperatures than the Sivetz roast.

In the current babble, the Diedrichs's roast has a non-declining rate of rise and spends roughly equal proportion of time at the different temperature ranges. In the current babble, the Sivetz roast has a declining rate of rise of and spends a proportionally more time at the high temperature range than the low. Given the unclarity of this verbiage, the relation of "rate of rise decline rates" and "roast proportions" may actually surprise you if you haven't read old school roasting instructions.

So which profile is best?

Again "rate of rise decline rates" and "roast proportions" is not going to tell you; whereas looking at the graph or simply saying slow start/fast finish and fast start/slow finish will. The straight line Diedrich's roast will spend more time in the Maillard browning range, and less it the caramelization and dry distillate phase of the roast. Its roast flavors will therefore be balanced towards savory. The Sivetz roast will have roast flavors balanced towards caramels and dry distillates. In both roasts, the origin flavors will be the same, and their strength, compared to those of the roast flavors, will depend on the absolute timing and degree of roast.

Which is better? Depends on how well the various savory, caramels and distillates in any particular coffee taste.

And now, after this brief moment of clarity, I return you to your regularly scheduled "rate of rise decline rates" and "roast proportions" infomercial and testimonial programming.
Jim Schulman

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#69: Post by bohemianroaster »

another_jim wrote: (although in the interests of politeness; I'll restrain myself from calling them obscurantist mystification).
Oh, tut tut! :mrgreen:

"Behold! Thy curve shall be determined by the nature of thy machine."

Currently I'm pushing the limits of what my Diedrich will do in terms of seriously restricting airflow until late in the roast, while starting with a high charge temp and finishing fairly fast - what I imagine a Probat might do . . . but my roaster ain't a Probat, and jacking the thing around any more than I do just gives me caca in the cuppa.
Jim, maybe what you're saying is: "Behold, there is nothing new under the sun" - Ecclesiastes
(This tidbit of wisdom brought to you by Jack Daniels) :oops:

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cimarronEric
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#70: Post by cimarronEric »

Just want to say, Jim, I bought Scott's book and it has given me concise, clear food for thought and hypotheses to test. I don't take anything on the forum, in any books, in seminars, in online classes etc... as doctrine but as nourishment for the process of honing a craft.

AND I would be first in line to buy if you were to put together a compilation of all your thoughts regarding roasting. Just saying there could be $50 (from me at least. I bet others on the forum would buy) in your pocket if you pull together an ebook. 8)
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