Scott Rao is the person who advocates the post-1Cs RoR crash as the "baked" roasting defect. To reliably detect this feature by computer aided software, one will need more than decent hardware and some fundamental knowledge of the data analysis process. He gives his advice for free, and he will be more than happy to become anyone's consultant for further inquiries.

I have followed many people's roasting tips for many years, including Rao's book and his blogs. My principal is that, I'll have to firstly learn to consistently roast according to those specified styles, and then I'd let the taste in the cup be the final judge. I won't comment on the blanket statement of taste here and will only share my method roasting to Rao's style.

There are multiple ways to mitigate the post-1Cs RoR crash. Charging hotter and applying higher heat at the early stage is one effective way. I often use this method to roast a Kenyan. For some of high moisture content beans, I'd need to push the Dry phase (room temperature to 300*F on my roaster) shorter (say less than 3:30) to prevent the post-1Cs crash. My machine is a commercial solid drum double-wall sample roaster, and it can store and transfer a lot of heat in the Dry phase without any ill effect.

Another trick is to closely follow Exhaust Temperature (ET). When I see Scott Rao's published roasting graph, I recognize it as isothermal roasting condition and the BT resembles a Power function defined by Newton's law of cooling (or "heating" in this case). My ET probe is located in the pipe leaving the drum. Since I know the temperature of 1Cs and the RoR, I can expect the remaining time to 1Cs (a handy tool in Artisan). I carefully control the heat/fan combination around 20 seconds prior to the 1Cs, so that the ET can be maintained at a constant value (e.g. isothermal roast; constant heat leaving the system) for about 1 minute. I only adjust gas about 40 seconds after the first crack start. In thinner drum roaster such as Huky and Quest M3s, I expect closely monitor/control the MET (the heat entering into the system) during this critical time period (pre- & post-1Cs) should have similar effect.

Before reading Rao's article, I took the time/temperature point of First Crack Start as the distinct segment point. I altered gas/fan combination at this point and in my mind linearly extent it to my planned time/temperature target. After Rao's article, I simply shift the adjustment time 20 seconds earlier and use a curve (a Cubic function) projecting to my time/temperature target. I can use this method to roast earthy beans to darker level while following all of Rao's parameters. Rao's curve doesn't conflict with Rob Hoos' time/temperature segments of flavor modulation, and Rao just points out one of his favorite curve. I don't always agree with his recommendations and explanations, but as I mention earlier in this post, as least I'll have to roast into his style and let my taste buds being the final judge.

It might not be just post 1C crash. Pardon the images, but I didn't save these profiles, just printed them so I can bring them along to the bar to taste. Both are my espresso roasts. Both taste very similar, almost identical. But the one with the steep dip after dry has a bit of the same "baked" aftertaste I found in my Sumatra with the dip & flick. Its not nearly as pronounced, but it is there. The reason for the dip was to stretch Maillard a bit.

The little flick around 10:10 on the 2nd roast did not affect the taste. There was no roastiness whatsoever.






And this roast from the other day is the best I've done on this coffee in 3 years. It was juicy and dynamic. Two regular customers and a new one went out of their way to comment on it.



So far nothing I have roasted has contradicted Scott's assertion that a steadily declining RoR with no "crash" yields the best result.

OldmatefromOZ wrote:Generally, I have found that increasing heat at FCS is not the answer.

This could be true in a drum roaster, where the added heat carried in the drum could be harder to cool before the flick phase.

On an air roaster, I can easily turn the heat up for 45s and then turn it down to prevent the flick. Easily might not be the right word. It is still tricky. But I am only starting to try this and should get better with every roast. The taste in the cup is well worth the attempt and any reduction of crash/flick has shown to be a significant improvement.

I just tried to duplicate the Goldilocks roast of my Colombia/Brazil blend from the other day. I started with a cold roaster so it took more to get it where I wanted, but other than the little flick at the end where I looked away for a minute, I think I nailed the RoR curve pretty well. Time to dry was a hair longer, 1C at almost the same time but a few degrees lower, total time 2s apart and final temp a few degrees apart.

This will be interesting tomorrow to compare these 2 roasts side by side.




And I just tried a 2nd and controlled the flick somewhat. I'll be brewing up all 3 of these tomorrow.

So I had a chance to tastes the past 3 profiles from above. The first (The Duke) is the goldilocks roast. Sweet, juicy and dynamic for a pedestrian Brazil/Colombia blend. A coffee most would be loath to add any sugar or milk.

In general, the second and third profile roasts tasted very much like the first. Customers could easily tell they were the same coffee. But all liked the first better. The second was less dynamic and sweet, with a hint of roastiness. The third was the same, but less roasty.

From these little experiments I've gleaned a few things. RoR dips of 8-9*/minute are noticeable and manifest as a flat, less lively cup with a lingering astringency on the tongue and upper palette. Flicks of the same degree add a roasty quality.

I know this is not news, and Scott has been touting this for a while, but this was my first attempt to taste it for myself by A/Bing several roasts along with the profiles to try and connect the dots.

I've come to believe that a steadily declining RoR, without significant BT swings is the path to a tasty roast. Manipulating the speed and benchmark time/temps can change the flavor profile, but not result in the significant roast defects generated by abrupt BT temp swings.

Last night I did a dark roast of the same coffee. I'm sitting at the bar with a cup as I'm typing. If I didn't know better, I'd swear someone snuck 1/2 a teaspoon of sugar in my cup. I couldn't ask for better in a dark roast. Not a hint of roastiness, sweet as can be with no astringent aftertaste whatsoever. This is now my roast template for this coffee:



Although I've learned, and Scott has confirmed, RoR consistency supersedes other "rules" like 20-25% RDT, this roast being a bit longer ticks all the boxes.

I'd still like to get it even smoother, but I am limited by my equipment and roast environment. Now that Artisan is set up to "see" better, I'm coming to believe I'm getting small power fluctuations that is making it difficult to maintain perfectly steady heat. I would love to have a real time wattage monitor to see the actual power that being applied. Maybe there is a way to read amperage across a shunt on the contractors? I also need a better control than a simple 500K pot and maybe a voltage regulator to help maintain a constant voltage coming in.

Almico wrote:RoR dips of 8-9*/minute are noticeable and manifest as a flat, less lively cup with a lingering astringency on the tongue and upper palette. Flicks of the same degree add a roasty quality.

Alan, thank you for that gem. It's a takeaway I'll bring to my next roasting sessions.

I'm not sure it's a gem yet. But I have not seen any scenario where it hasn't held true. Proceed with caution...

Almico wrote:I'm not sure it's a gem yet. But I have not seen anything yet that where it hasn't held true. Proceed with caution...

You don't get anywhere with this roasting thing unless you dare to brown some beans!

EddyQ wrote:Lot of good info here Al. Thanks for sharing your journey.
I haven't had a chance to work my roasting in this area for a few weeks, but it is on my list of things to do.

If any are in Seattle in April, Scott is having a class about this topic.

https://www.scottrao.com/blog/2018/3/17 ... s-seattle-

I just got pre-authorization from my wife for this one, flights from CLE are only $121 round trip!