Which do you go by?
I've spent most of the afternoon doing searches and reading post on different strategies and profiles for Guatemalan beans. It looks like TomC and has spent a lot of time playing with different Guatemalan roast and seems to be an advocate of slow in fast out. Like 9:45 to FC and 11:23 finish. This definitely is outside Rao's 75-80% magic window for FC.
I also respect TomC's and several others advice and inputs that that I feel know just a little bit (more like one hellavalot) more than I do about roasting a coffee bean. At the same time, you read and hear about all this stuff from Rao, who I guess is supposed to be one of the coffee gods, basically saying if it's not within that FC window, it's probably not great coffee.
So, I just received 10 pounds of Guatemalan beans I want to learn how to roast. Do you listen to those whom you respect their inputs and go for the slow in, fast out, or try to keep your profiles in that magical 75-80% window, and maybe try that little hot kiss right on the end.

Thank you for the compliment, but your focus should be on what works for you, not what I say or what anyone else says. I don't stick to any hard and fast methodology for roasting other than doing what I feel tastes best for a given batch. More chefs in the kitchen is fine, but it doesn't mean its going to taste any better. I like playing around with methods and approaches that others advocate and seeing how I perceive them in the cup where it matters.

I'd suggest picking one approach and following it until you can consistently execute it's profile, then tweak things and see what happens. Whether it's Rao or anyone else, go with whatever tastes best to you. It will be entirely dependent on what type of gear you're using and thermocouple placement etc.

TomC wrote:...but your focus should be on what works for you,...

Agreed. When I get a new coffee in, I like to do my first profile. Cup. Tweek for roast 2. Cup. Tweek for roast 3. Cup and determine what has worked best and go from there.

I wouldn't worry about whos methodology your following, as long as you dont get stuck in the "this is always true" for coffee you will be set. For Guatemalas id try a long stretch to crack (like 5-5-130 to 230). And then the complete opposite as well, with something like 4 - 4- 330. Then adjust to taste. Why limit your self to only one type of roasting?

I've been noodling around the difference between development time and development temperature, while still keeping within Rao's guidelines.

In other words 3 minute development time at 420* drop vs. 1-1/2 minute development time at 440*. I still want to keep a declining RoR, but I want to know the difference between more and less convex curves.

I drew up this target curve in Artisan designer:



and just did this roast of last years Hacienda La Minita:



429* is my normal drop temp for a 12 minute roast, 3 minute development and 10* RoR average after 1C. This roast maintained a post 1C RoR of almost 25* and a ramp RoR of over 40*. 2 minutes to 212*, almost 20% development.

I just brewed a quick Aeropress right off the roast and it is not underdeveloped in the least. I'll try it again tomorrow and in a few days to see where it goes.

Next time I want to go shorter development and hotter finish.

Thanks for the reply. With this modern computer age and a TC4 PID, creating and repeating profiles is not a problem. The problem is, the profile is no better than the persons knowledge of the best way to roast the bean they are using, and that's were I suck. I have two serious limitations and still trying to figure out to get around them. My first, I'm using an air roaster that's noisy enough, my hearing has gotten so bad at upper frequencies, I can no longer hear the first cracks. I've even ordered a high gain, directional mic to try and that didn't help. I'm gather materials to make a roast chamber I'm just going to feed off my flow bench I can remote away from the motor noise and see how that works (you recon 12ea 100 cfm vacuum motors will deliver enough air). So, for now I'm just assuming the first cracks are at the same points they were back when I could hear them. The second is some really dumbass taste buds. Even though I've roasting for 15 years, I've never really liked black coffee and have always drank it with sugar and milk, and always judged it by how it tasted then. Now, I've started doing at least two six ounce cups, cupping style a day (black) trying to learn how to taste the different flavors that are supposed to be in there.

That's why for starters, with these beans, I have been reading and trying to learn which is the better strategy. If the slow start, fast finish produces the most flavors, the why mess with Rao's theory. I just didn't want to do a dozen roast tweaking different parts of the curve, just to find out, I should have been doing it different and start from scratch again. I just made one roast about noon time today and just to get and idea, I tried it about 7pm, and it dang sure wasn't anything to brag about. 398F (I used for FC) was at 09:00 and 418 finish @ 11:15

I use Roast Logger, with the TC4 PID and just redid how I've doing it so maybe tomorrow, I can get a good roast and see if I can figure out how to post it for pointers.

If your air roaster is causing the ror to increase around fc that is likely NOT meeting raos guidelines despite hitting the percentages. To improve tasting I would highly recommend buying from a good roaster. Too many variables to do it all at once I think-roast would potentially obliterate everything, grind and brew might e slightly off, then how could you possibly refine your palate?

Do you mind if I ask what air roaster you are using. I have spent many hours with my sr700 and have finally started nailing rao percentages and declining profiles spot on (using the beta software) I think most home air roasters are NOT capable of this based on the features I have read being available to control heat.

Also, where are you getting your green and how d is it. I just discovered I had a small stash of green from about 8 months ago I hadn't finished, my wife "put it away" for me. It would have one or two snaps at fc, then even when the temperature went up it failed continue audibly snapping, despite clearly roasting to temp. Seems that they had dried out already and we're basically stale. Maybe you have older green contributing to the hearing problem?

Not sure what you would even consider buying in an air roaster that roast 120-200 grams of beans that might even come close to matching the performance of mine, but you can bet your sweet ars that SR-700 won't come close. You can't "buy" a production air roaster the size of mine that gives the capabilities it has.
As for what kind is it, if you saw it just sitting on the bench, you would think it's just an old iRoast2 that has seen it's better days and just a piece of scrap sitting there. However, is like the old bootleggers car, looks can be deceiving, it ain't made to look fancy, it's made to go, and it will do that.

I'm going to try and get a roast in today and post a graph from RoastLogger if I can figure out how. I don't have one after redoing my process. The one I just roasted, I forgot to turn the auto heat control on the PID on for the first 1 1/2 minutes so it had a funky roller coaster right in the beginning, and was too cold in the garaged for my to do another, plus I was wanting to do more research on profiles for Guatemalan beans.

As to profiles specifically for Guatemalans, take heart in knowing that they're extremely forgiving coffees in general, that taste great across a wide spectrum of roast developments with nice clean structure/acidity, good sweetness and soft chocolates mostly. They're kinda hard to do badly IMO.

Almico, that profile is similar to what I have been doing in the past but a little faster. A 30 RoR from 280 to 380 and then start slowing it down in steps to 405 and then a 10 RoR to finish for my pour over coffees. I would usually try to keep mine around 8:30 for 428 degree finish and 9:30-10:00 for a 440-445 degree roast.
I've always stayed away from lighter roast until about a month ago because I'm not a fan of acidic coffees. Then it seems the more I read and learn, a lot of people are ending roast in the middle and right at the end of the first crack by slowing down the drying phase, speed through the middle and slow the finish, or slowing the whole thing down and speed through the finish and roasting a lot longer, more like 11:30 to 410-415 degrees. So I ordered me a bunch of Brazilian since it's a low acid coffee I like that gives pretty good balance with lighter roast and have been experimenting and gotten some pretty good coffee using that slow, fast, slow profile. Friends and neighbors are loving it also. There is no way I could ever drink all the coffee I've been roasting the past month so I've been giving away a lot of fresh roasted coffee. One neighbor is liking it so much, he's trying to get me to set up a coffee shop and he would fund it.
Now I've decided to step it up a notch with beans on the acidity level with a couple different Guatemalans and see if I can start getting those off the wall flavors I keep reading about in the cupping notes people keep describing. Which is going to be hard for me because I've never even heard of a lot of the flavors some describe, much less tasted them, and definitely not in a cup of coffee.