3 samples of natural Kenya Kitui

[LTB]

Hi everybody !

I tried three roast of the same bean, with quite the same devellopment, but with different charge temp.

I didn't ended really like I wanted, maybe be due to the too little amount of beans (200 grs green, more or less 170 grs roasted)

The coffee is a Kenya Kituy, natural dried. I will post later note of the cupping (note very good in that exercise) and further of expresso extractions.

Here are the artisan log, please note that the red curve is not ET but actually MET (and the orange one is then delta MET).

[edtbjon]

Well, they seem quite ok to me, but there is room for improvement.
First about the charge temp. When I roast I aim for a turning point (TP) of 100C. You seem to be very close to that in the 2'nd and 3'rd roast. I don't know if you have found a setting for "Auto TP", but that is very nice to have Artisan to mark out for you.
You don't tell how you use the gas and air, but from the DeltaBT/RoR curve I can tell that you probably are giving the roast more heat in the middle of the roast. When I roast 200g charges (with a perf. drum etc.) I start the roast with almost no heat (< 0.5 kPa) for the first minute, just to have a burning flame there. At the 1 minute mark, I turn the heat up to 2.0 kPa to give the roast a good boost of energy. I use a Variac and have it set to give a very small negative pressure in the drum, which also creates a small airflow for the burner. At around 3 minutes I lower the heat to 1.5 kPa. I usually aim for the roast to be at DE (dry end, 150C) at 5 minutes, which I get with these settings. At 150C I rise the airflow to 40% of maximum, which will make the RoR continue to drop at a good slow and steady pace. I may have to adjust the heat a little bit (down) so that I have my 1Cs (1'st Crack start) at around 9 minutes. (I close the grate at 190C...) Finally I rise the air a bit more when going into 1C and lower the heat to about 0.5 kPa about a minute into 1C.
A short way of describing the above is: Begin with high heat and low airflow. In the middle medium heat and medium airflow and in the last stages, low heat and high airflow.
There has been lots of discussions about this "falling RoR commandment" and Scott Rao, who writes about it in his book. I usually try to roast with a falling RoR and I recommend it to anyone who is new to roasting with the Huky, not because it's the only way to roast, but it's a good way to learn the roaster and how to control it.

[LTB]

Thank's for your comments, edtbjon.

I indeed put on the "Auto TP" but you can see that it didn't seemed to work at least on one of the roast (why ? I don't know....)

I didn't find how to mark on artisan the gas power and airflow (maybe I have a too old version of artisan, should find the newest one).

I proceed in a slightly different way than what you describe : I try to have a bit longer drying phase and a shorter caramelisation phase. In that idea I start without any gas power, starting gas power after TP, going to the max more or less one minute after TP. It's relativly clear on the delta BT of the first roast, wich was the closest to what I aimed - what won't necessarly turned to be a good roast !

Well, that's kind of profil is quite difficult to handle for me. Your way (falling RoR all along) is much more easy to put in practise ! Next time I will go for that and compare.

Thanks for any comments, they are more than welcome !

[SusanJoM]

I didn't find how to mark on artisan the gas power and airflow (maybe I have a too old version of artisan, should find the newest one).

Look here
https://drive.google.com/folderview?id=0B4HTX5wS3NB2TFVid0h2TGxBWG8&usp=sharing

[LTB]

Thanks Susan ! 

[LTB]

Well, time to tell you what I think about those roasts.

It's difficult for me to write an extending thing in english, and I'm not even sure it's necessary, so I will juste give my impressions shortly.

My impressions are based on bean smell and ground bean smell 14 hours after the roast, one week after, 9 days after, and on one cupping 14h after the roast (tried to make a cupping in the best conditions) and a few expressos 9, 10 and 11 days after the roast.
Time laps is because I was away from my house.
Expressos were double shot ritrettos with the rancilio silvia.

I numbered the roast (1 is the first one with the lowest charge temp and so on).

Impressions now :

Nose and Cupping :


1 is the more fruty, quite expressive (smell), with little strange rear taste (after taste ? back taste ?) and fermentation and herbal taste. (cupping)

2 is the less expressive, more classical nut/chocolate (smell), the most equilibrated and roasted (cupping)

3 has sparkling odors, spice and floral (smell) fruty and a little agressive, balancing between acidic and bitter.

expressos :


2 is the clearest, straighest, most acidic and laking of complexity of the three. I did'nt liked it, nothing interesting for me in expresso (well, all of this is according to my taste preference, obviously, no truth in all of that)

1 and 3 are quite similar, with acidity but not only, 1 being maybe the flavourest and 3 the more complexe and powerfull.



Now, all that saying, I don't know how to do, why there are so much differences, etc.....

For exemple 2 and 3 profils are closest than 1 and 3 profiles, but in cup 2 is very different from te others... The main difference between 2 and 3 profils is the declining RoR for the number 2.

Any idea or critics welcome !

[JavaBuzz]

Hi LTB,

Just a quick observation from a quick glance at the profiles (so take it how you think best):

It looks like the Phase 1 times are pretty slow (6.5-8m)? Could try shortening this to around 4-6m (probably shoot for around 5 min to start) and see if that helps. Shortening this phase might help bring out the flavors more and make the acidity more interesting.

Also, very difficult to start out at 200gr (can be difficult to roast at that weight even if you're comfortable with the roaster). Charges around 400gr are probably a good starting point (I'd highly recommend not going below 300gr when starting out).