Speckled beans

#1: Post by **Peetee** » July 31st, 2015, 5:23 am

Hello all,

I have a problem with a Gene coffee roaster. I am probably doing something wrong, but I don know what. My coffee is very unevenly roasted. There are speckled beans as you can see from the picture.
This is washed Ethiopia GR1 but the same results I have with Brazil pulped natural. The batch for the Ethiopia was 250g. What am I doing wrong?

#2: Post by **erik82** » July 31st, 2015, 6:55 am

What was you roast profile? Total times and temperatures (real and selected) per minute interval. When did yellowing, first crack and second crack happen. Without all the information it's hard to find out what you're doing wrong. Your batchsize is ok and that's the only thing I can say about it with this amount of information.

A better photo which isn't so blurred will also help.

July 31st, 2015, 6:57 am

It was supposed to be roasted light. Here is the profile

time temperature Note
00:00:00 80
00:53.42 90
01:21.72 100
01:47.85 110
02:04.79 120
02:25.48 130
02:56.47 140
03:17.57 150
03:49.47 160
04:23.10 170
04:56.11 180
05:26.08 190
06:36.19 195
07:13.36 200
07:41.92 205
08:31.52 210
09:16.62 215
10:15.22 220
11:05.84 225
12:05.89 230
13:22.09 235
15:18.30 235 First Crack Begin
16:48.83 240
17:21.21 240
17:21.71 240

I will also upload a new photo in a few minutes

July 31st, 2015, 7:30 am

Here is a better photo

#5: Post by **Boldjava** » July 31st, 2015, 7:35 am

15 minutes to first crack is much too long. On my Gene Cafe, I am getting first crack between 9:30 and 10:30 for 90 percent of my beans.

You either have your heat setting too low or you have a low voltage problem. I suspect voltage as the photo indicates insufficient heat. For most of my beans, I set it at 242C and turn down several degrees after 45 seconds into first crack.

July 31st, 2015, 7:43 am

Yes, but the lower temperature increase was my intension, I supposed that it will be better when the temperature will raise slower. So you suggest to heat it up to 242 C and after first crack decrease the temperature let's say to 230?

And do you suggest decrease the temperature right after I hear cracking, or wait on 242 few minutes after cracking and then decrease?

I really want it light roasted, no oily beans or bitter taste...

#7: Post by **Boldjava** » July 31st, 2015, 8:03 am

Turn it down to 239 after 45 seconds into first crack. I would also suggest that you not cool the beans inside the Gene. Devise a system with a shop vacuum to cool the beans externally.

You can end the roast any time you want. There is no need to go to second crack just because you are roasting at 240C. I would also encourage you to get 5 pounds of any bean and just practice on that one bean until you have learned your roaster. Good luck.

July 31st, 2015, 8:18 am

A did as you said and here is the result. I can generally say that the roasting is more even then before, but if I will be pedant, then I can still see the uneven roasting.

#9: Post by **erik82** » July 31st, 2015, 8:27 am

First thing. Pre-heat the Gene (empty drum) for 5 minutes set on 220C. After the 5 minutes it should be around 220C. Do an E-stop and put the beans in the pre-heated drum and start roasting. This will make a big difference.

Secondly I never set my temp higher then 230-235C on my 230V Gene. It should be enough and avoid scorching. Seting it to 240C will scorch the beans on a 230V Gene and will not be able to get light roasts because they will roast way too fast. After pre-heating and putting the beans in and setting the temperature at 230C the beans should turn yellow in around 5 minutes, caramel in around 5:45-6:00 and FC at around 9:30-10:30 with EOR at around 12:00-13:00 minutes.

You can turn down the temperature at around 30-45s after the real start of FC. Set it to 225C for a slow and good development and you can extend FC for 2 minutes and stop at 2:30-3:00 min after the start of FC and get a City(+) roast.

Never cool the beans inside the Gene because it sucks. You can use a shop vac to cool like Boldjava said (it works great) or use a fan and two sieves to transfer the beans from one sieve to another in front of the fan (it will also blow away the chaff so do it outside).

My profile will be something like this (have roasted around 450 batches so far with my Gene):
After pre-heat and putting in the beans set the temperature at 233C
1min 180C
2min 185C
3min 192C
4min 200C
5min 206C
6min 212C
7min 218C
8min 225C
9min 230C
Somewhere in here FC will start
10 min 230-223C (depending on when FC starts set temp to 224-228C dependend on beans and roast level)
11min 226C
12min 228-232C (set to 233 if you want full city(+) or set to 227-230 for City(+))
13min EOR (after 2:30-3:00 minutes after the start of FC do an E-stop and cool)

Hope this helps.

July 31st, 2015, 9:23 am

Dear Erik,

thank you for your advices, I have tried your approach, but with this temperature (233 when FC) I had much worse results then before. I made exactly as you described, but unfortunatelly, it does not work for me. See the picture please. It seams that the FC temperature must be higher.