Saturday, 29 June 2024

Roast 5 - PNG arabica - medium roast using a kitchen drum-air fryer

 This is a re do of roast 4.

I'm using a kitchen air fryer. I picked this machine over your standard tray air fryer as it has a drum. However, the temperature is difficult to precisely measure and control.
These were my measurements from the last roast:
Time               Temp         
0 ....                200c charge 
1.30                169 TP
2                     163
2.30                153
3.00                148
3.30                144
4.00                143
4.30                146
5.00                150.... end of yellowing phase
5.30                155
6.00                163
6.30                170
7.00                175
7.30                179
8.00                181 ... end of browning phase
8.30                184  FC. start development phase
9.00                190
9.30                196
10.00              202
10.30              END roast temp 207C


The coffee was very light (which I like) but my original aim was to get a medium-dark roast.


So I'll up the temp targets by 20C overall and use less beans.(150g)
Target temps:
0 min Charge: 220c
3.30                 160
5 min               170
8 min                191
8.30                  204
10                    220
end roast          230
These temps all seem very high but I suspect the bean temp is 20C cooler

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Roast 5
PNG Simbu Arabica

so there is a bit of guess work here.
The fryer only has a timer & temp control knob which is not accurate.
I was playing it constantly during the roast and reading these temps

time                 Old Temp New Temp
0 ....              200c charge ................ 215
1.30          169 TP ............. 191
2                      163..........................................................192
2.30          153 ....................... 192
3.00                148 ........................ 184
3.30                144..........................................................182
4.00                143 ........................ 175
4.30                146 ........................ 171
5.00    end of yellowing phase  150........................................167 
5.30                155 ........................ 166
6.00                163 ......................... 167
6.30                170 ........................... 173
7.00                175..........................................................179
7.30                179 ........................ 188
8.00  end of browning phase     181 198 
8.30                184  FC. start development phase........  213
9.00                190 ......................... 214
9.30                196 ........................ 209
10.00              202 ........................ 207
10.30              END roast temp 207C ......... 220


start weight 150g
end weight 132g
18g weight loss ... 12%... medium roast ?










I was happy with the final result.
This roaster is certainly not good for precision or repeatability but I enjoy a challenge.
Every roast you do will be unique.


You need to keep an eye on the temperature and adjust the temp knob up or down
to keep the temp on target.

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To do a medium roast on this machine with 150g beans my targets are:
0 min ... charge temp of  220C
1.30                aim for     150C (tipping point)
3.30                aim for     160C
5mins             aim for     170C (end of yellowing phase. entering browning phase)
7mins             aim for      180C
8mins             aim for      200C end browning phase 
9mins             aim for      215C first crack ???
10 mins          aim for      220C   finish here. (drop)

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