Development time as a ratio of roast time by Scott Rao

#1: Post by **farmroast** » May 27th, 2014, 9:12 am

A new function guest added to Cropster roaster software by Scott Rao. Considering development time as a percentage of total roast time. Obviously you don't need to be running Cropster to consider this. Here is the blogpost with the mention by Scott. development-time-ratio

#2: Post by **TomC** » May 27th, 2014, 4:02 pm

Great article, as with all of Cropster's articles. The only thing I think he's overstated is the point on the development time lowering sweetness in almost all roasts. I agree with the fundamental point, so I'm likely unnecessarily splitting hairs, but I wouldn't say that for every single roast. Some coffees need to be roasted slightly slower and slightly longer on the development in order to let the sweetness express itself fully, and yes, that is often due to taming acidity. Our recent Bolivian coffee from May's RLT comes to mind. It wasn't my fastest roast, but I took it to just past cinnamon in color and 1C was still finishing as it hit the cooling tray. It was loaded with snappy sugary sweetness and cinnamon sugar cookie notes.

I might toy around with Cropster down the road to see how it works versus Artisan. My custom probes should be here any day and I'm chomping at the bit to get my new system up and running. I know basic science can't be patented

maybe this is a feature buried in Artisan already, I don't know, but if not, I'm pretty sure it can be added. (Other than the color graphs and percentages of each stage at the top of the profile) but that might be the majority of it right there.

Thank you for highlighting this article.

#3: Post by **endlesscycles** » May 27th, 2014, 5:20 pm

Any increase of sweetness from longer development times is definitely perception relative to acidity. Assuming enough of a crack occurred to liberate sweetness. There's obviously a bell curve with a steep left side.

I think the ratio concept is a good guideline, but he withheld the reasoning which would permit better understanding.

#4: Post by **yakster** » May 27th, 2014, 5:24 pm

What I got from the article was that this was a statistical observation, that the best roasts fell within this development time ratio, and that there's no developed theory of why this is except for the analysis of the roasts.

I found the article interesting, but I've been thinking about roast development both before and after first crack, and this ratio takes into account only roast development after first crack without regard to the type of profile leading up to first crack. I guess I'm thinking that there might be more to it, but I'm also thinking it would be interesting to test this out myself.

#5: Post by **TomC** » May 27th, 2014, 5:39 pm

I just think Scott Rao likes to use blanket statements, usually that stretch a bit too far. But there's pretty much always a foundational truth they're built on.

#6: Post by **boar_d_laze** » May 27th, 2014, 5:43 pm

What I got from the article was that this was a statistical observation, that the best roasts fell within this development time ratio, and that there's no developed theory of why this is except for the analysis of the roasts.

"Empirical," maybe. Not "statistical."

I just think Scott Rao likes to use blanket statements, usually that stretch a bit too far. But there's pretty much always a foundational truth they're built on.

+1.

I think he's on to something, but that reality is more complex than the projection. For instance, you can get "baked" or damn close to it with a Development interval within Rao's prescription if Drying proceeds too slowly. For instance (and for my sins):

Rich

#7: Post by **bohemianroaster** » May 27th, 2014, 5:50 pm

My best roasts fit his paradigm perfectly. Cosmic significance?

#8: Post by **bohemianroaster** » May 27th, 2014, 5:56 pm

And who's gonna need Cropster or Artisan anymore after this:

http://dailycoffeenews.com/2014/05/26/a ... -roasting/

#9: Post by **another_jim** » May 27th, 2014, 6:38 pm

boar_d_laze wrote: For instance, you can get "baked" or damn close to it with a Development interval within Rao's prescription if Drying proceeds too slowly.

Hooray! One person actually knows what a ratio is. The conversion of sugars into caramels, and hence the loss of absolute sweetness is a function of the actual roast time above 395F, not the ratio of that time. Hence the entire statement is mostly BS. The portion that is real is that the actual roast time depends on the heat transfer rate, and low convection roast processes have inherently longer times that high convection processes. So the ratio observation may have same observational validity as cockcrows causing sunrises.

TomC wrote:I just think Scott Rao likes to use blanket statements, usually that stretch a bit too far. But there's pretty much always a foundational truth they're built on.

The decrease of chlorogenic acids also happens roughly above 390F; and decreasing these is vital to getting roasts that don't taste raw, rough, acidic and bitter. If one could know the precise rate of decay of sugars and chlorogenic acids as one gets into the 1st crack, one could stall the roast at temperatures where the decay of chlorogenic acids is fastest, and speed up where the decay of sugars is fastest. This would be the most scientific way of getting the most perceptually sweet light roasts.

I've roasted a long time, and have no sense of how these sugar versus chlorogenic decay rates respond to temperature. It would take precise and long winded experimentation to work out.

#10: Post by **Almico** » May 27th, 2014, 6:42 pm

So...by this assumption, my 31 minute roast, where FCs was 27:00, was underdeveloped.