Critisize my roast

[Adondo]

Hi guys! I've started working with a colombian bean with the quality expressed as "Washed Arabica Caturra and Typica, SHG screen 17/18, Supremo".

I've done the three following roasts.

Roast 1 - This was very flat and too bitter for this coffee.


Roast 2 - This was less flat, although too bitter.


Roast 3 - This was much closer how I wanted it to be, more bright and acidic than bitter. This was however on the edge of being too sharp.


With my current stove (not Mr.Li's) I feel like the lowest setting gives too much heat, hence the high ROR at the end of my roasts. Either it is "low" which in my meaning is high, or it is off. Turning of the fan is not something I want to do, specially at the end of the roast. I have turned it off with decent result in the end but it ended leveling off too much, as the temp was nearing plateau (hence roast 3's increase of ROR in the end). Furthermore I feel like the ROR is very hard to get to a desired rate, either it is too high or decreases too rapidly. This could be due to my stove but would be interesting to see if others have had similar issue.

Any advice for this phenomenon and adressing my profiles differently in order to achieve a pleasant acidity? Help is greatly appriciated.

[edtbjon]

First, "Hej och Välkommen"...

I take it that you're using a stovetop or something similar. It's up to you to decide on investing on a IR stove from Mr Li, which is very easy to regulate in the lower heat regions. I took the cost of that burner over any ordinary BBQ burner or a stovetop burner (which I didn't have anyhow). I've been looking around from here (in Sweden) for the last two years and havn't found anything coming close to the IR burner from Mr. Li in terms of a good burner for roasting with a "halvkilo rost". In my opinion good control of the heater is the first thing to look for (and the IR burner certainly has that...).
Apart from the heat control (or lack of it...) how do you control the air? A proper "Variac" may be overkill, but you can do with some kind of precise and repetitive controller. I.e. a simple dimlight control isn't good enough. (It's not very common in Sweden, but a "router control" ("kontroll till en överhandsfräs" som jag aldrig har sett på svenska) is what you're looking for. Personally I found a decently priced "Variac" style controller at TME.eu. (PM me for details...)

Now, about what matters, the roasts. It's always about what the roasts taste likes, not the graphs, but even though the second seems like a decent roast, from a "Scott Rao" perspective, it's probably too long which is why you experience bitterness. I'd say that it's a matter of finding a balance between roast 2 and 3.
Feel free to PM me to communicate in Swedish, which may be easier...

I edited for a few spelling errors...

[Adondo]

Ive been using a bbq side burner until now. I have however ordeted Mr.Li's stove the other day so Im waiting for the deluvery. Will use it with LPG or gasol in swedish.  When it comes to the fan control I havent looked much into it yet. I have adjusted it with the help of scott rao's suggestion to use a lightwr. Ill pm you regarding the controller, thanks!

Avsolutely, totally agree! Will try to find the balance! Thanks!

[edtbjon]

I guess that Mr. Li have these burners on the shelf, so that delivery will be quite quick. With just some luck it should be at your nearest delivery point within a week or so.
Again, good choice, it's very easy to control in a very precise manner.

[LTB]

edtbjon said it all !

In france, we call a quick and relativly clear (in terms of color) roast a "nordic roast"

Anyway, the two first seems a bit too long. Well, like I said, edtbjon said it already !

[nikosgi]

not just long, but too steep delta in development phase I would think?
The last one you managed to control the temp much better peaking at 5C lower and having a more horizontal profile. Adding to the quicker overall roast it seems to tie in w ur tasting experience.
Now try to repeat this!

[coffee_cat]

Charge temp variation latitude is might wide.

From my perspective, first two roasts don't inject enough heat into the roast at the outset, so delta BT is stalling and reversing. This is not desired.

Third roast, again subjectively from here, starts out in opposite fashion, putting too much heat into the system early. This causes the roast to run away and get out of control during the critical later phases.

In all three roasts, the drop off at 1cs seems too steep. Are we cutting the gas at 1c? Notice the upswing in #1 and #3, particularly. This is called "the flip" and pretty much kills the sugars.

The middle phase of the roast (what is often, erroneously according to Rao, called "development  phase" would ideally comprise around 30% of the total roast time.

For full disclosure purposes, a recent roast curve is attached. This to give perspective to my comments and allow others to criticize my comments as well.

[coffee_cat]

[coffee_cat]

Sorry for the image posting mis-steps. Working out image posting here. So, here's the curve mentioned in my comment above:

[Adondo]

I agree with your input, and the insufficient heat in the beginning I believe as well to be accounting for the reversed RoR trend after the onset of 1st crack. Judging by the profile your roast looks good, but 2 things that highens my eybrows are that you have a relatively high ET compared to BT (no idea if this was your intention or how to create this huge differentiation) and a pretty short total roast time. But I guess the latter is more dependant on the specific coffee and what flavours you want to enhance. Do you have a specific reason/flavour you want to enhace as an explaination to why you chose that short time of a roast?

I did this roast the day before yesterday and I'm very pleased with the results (by far my best roast yet). It has some very nice fruityness as well as an interesting acidity and not so bitter.

[coffee_cat]

Normally, after a 20 or 30 minute pre-heat, fan running @ 30% and drum spinning, the ET hits around 250°C (482°F) and stays pretty consisten throughout the roast. Variances refledct fan usage during the roast.

Without pre-heating, there's a significant period where nothing is happening but the roaster itself acting as a thermal sync and absorbing energy. This would take away from energy being applied to the beans.

Fan speed for the warmup and early part of the roast was set by using a lighter near the trier hole and adjusting the fran until the flame leans toward the hole, but does not go out (per Scott Rao's suggestion in "The Roaster's Companion").

[LTB]

Well, seems to me that it's actually no ET but MET probes that your graph is showing, coffee_cat, am I wrong ?

[SusanJoM]

Well, seems to me that it's actually no ET but MET probes that your graph is showing, coffee_cat, am I wrong ?

What makes you think that, LTB? 
Those curves look to me like ET on top and BT below.
But...let's see what C_C has to say.

[coffee_cat]

Yes, it's as Susan says. The MET thermometer on my Huky is analog.

[SusanJoM]

Okay, now I have egg all over my face.
I was looking at the wrong profile, LTB is right.
Coffee_Cat, your red line really is MET.

It was this statement The MET thermometer on my Huky is analog. that made me go back and look, because I have never heard of anyone replacing the digital T/C at MET with an analog. 
The analog thermometer that came with the HUKY is definitely at ET.
The curve the red line is describing is definitely MET.

If you want to track ET in Artisan you will need to order another T/C and a converter from Mr. Li and replace the analog thermometer with that.  Here is a picture of what you need https://www.hukyforum.com/index.php?action=gallery;sa=view;pic=28