Hello,

I thought I’d start this thread as I continue my roasting journey. I’ve got a dimmer modded gene cafe. My coffee preferences for now tend to be natural, fruity coffees and often use them for milk drinks, so really strong flavours prevail.

I’m getting there with the roasting, had some pretty good Yirgacheffe and rocko mountain roasts, but struggled with scorching.

So to the question for the experts. I’m finding the scorching occurs after first crack, but interestingly this happens around 215c. This surprises me given most guides suggest final temps from the gene cafe of around 230-235. If I had run that on my roaster, I’d have charcoal. Could this be a machine specific issue? Or are most of the guides suggesting too high a temp for natural coffees?

Thanks!

    Dan I’m getting there with the roasting, had some pretty good Yirgacheffe and rocko mountain roasts, but struggled with scorching.

    May not be helpful but is the scorching on these beans you mentioned? Ethiopian and Kenyan beans appear to roast darker due to the sucrose levels in the beans (especially Heirloom and Bourbon) grown at those elevations. The sugars effectively burn on the surface.

    Again probably not helpful as it’s a totally different roaster but here’s what I use for Natural Heirloom Ethiopian light roasts:

    La Marzocco Linea Mini - Mazzer Philos

      Frustratingly, I seem to be getting scorching with most beans I roast. I’m improving, but it’s still an issue.

      These are two examples, where I progressively drop the wattage from beginning of maillard to the end. But still have issues.

      Colombian natural castillo. Maxed out at 214c in a 14 minute roast. I think this just had too long after 1c and got too dark. I’ve been recommended to keep the bean temp below 205 so I perhaps just went too long.

      Yirgacheffe maxed out at 216 on a 13 minute roast. Could the veiny scorching be burnt on chaff?

        Dan

        The Yirgacheffe looks fine in colour to me, what I’d expect from that bean at that temp. Slightly uneven but I know it’s hard to get a decent photo to properly show even-ness.

        I’m not familiar with the roaster but can you get an Artisan graph or similar? How fast are you getting to peak temp? Naturals tend to benefit from a slower rise with longer drying time. You mention dropping the temp at the Maillard point so I’m guessing you’re reaching peak temperature before that?

        La Marzocco Linea Mini - Mazzer Philos

          Sorry yes, reducing the wattage reduces the rate of temp rise, rather than lowering the temp absolutely. Sadly no artisan though…

          As an example, it took:

          7:30 to get from 89c to 207c (to maillard),

          2:55 to go from 207c to 212c (to 1c) and then

          2:30 to go from 212c to 214c (to end)

            I do think the Yirgacheffe looks pretty good. Does it taste ok?

            The only thing I’d maybe try is a sharper RoR and slightly shorter development time. But again, it looks pretty good to me.

            Someone with the same roaster might be able to help more.

            La Marzocco Linea Mini - Mazzer Philos

            Thanks! Its the veiny burn which has me a little confused (it’s just about visible in the photo if zoomed in) . I roasted today, so will test in a few days.

            Funnily enough I roasted some yirgacheffe heirloom natural this evening. It does tend to roast darker in my experience as well. This was on bocaboca roaster. I don’t think the photo shows it well but the vein is on the darker side as well.


            mailto:kafar@btinternet.com

            Another good way to check for actual scorching is with a UV light, tipping and scorching becomes much easier to spot under a UV-A blacklight if you have one (eye protection recommended)

            Coffee Roaster. Home: Sage Dual Boiler, Niche Zero, Ode v2 (SSP), 1zpresso ZP6 Work: Eagle One Prima EXP, mahlkonig e80s, Mazzer Philos and lots more

            Dan

            How clear do you hear the first crack? Wondering if the beans actually reach FC. I’ve got a gene with a dimmer too. But FC starts at higher temperatures. You can guide yourself by the amount of smoke also.

            how many grams do you put in and how many do you get out?

            I’m curious how exactly are you using the dimmer. Is it based on power consumption? If so, at what wattages are you using it? I’m using it at around 1150W - 1200W. But can be lower in the drying phase or after FC. To have the beens develop longer without getting too dark.

            I can see starting temperature is 89. I suppose you preheat the machine. For how long? I usually preheat til 230-240C and it takes about 10 minutes. Charging the beans drops the temperature to around 150C.

            Lelit Elizabeth, La Pavoni, Niche Duo, Gene Cafe roaster

              I’m pretty confident I hear first crack, but will admit it I remark it on occasion if I feel I noted it too early initially. The coffee tastes sufficiently developed to have passed first crack though. I dont get much of the grassy, bready flavours that characterise an underdeveloped roast.

              I’m terms of wattage, I usually have about 1235W with the dimmer switched off and drop the wattage at 20W increments to control the temperature rise. I don’t use specific watts as a guide given different ambient temperatures, but instead watch how the exhaust temp rises on the machine.

              I aim to have roast times as follows –50% drying phase, 25% maillard and 25% development period for the roasts. I usually aim to avoid 2c in part due to the scorching issue. This means a really slow ror after 1c. I would love feedback on whether that is a good approach for a medium roast! And would be interested in how others go about it.

              Finally in terms of charge temp, I use the stop function on the gene cafe rather than estop. The stop function ends the cool down cycle at 100c, so depending on how speedy I can be, the 250g of beans go in at around 85-90. The final cool down cycle goes all the way to the bottom to avoid heater damage.

              I’d be interested in views on the above the wealth of info out there on these machines seems to miss a bit on dimmer profiles, so views on the topic would be interesting!

              I’ve just bought 5kg of a this Natural castillo, so will be testing profiles going forwards.

              Dan

              I remember reading a post by @DavecUK where he talked about roasting beans and comparing them to"frogs & toads" ( the toads being undesirable), that one in particular certainly looks more “toadlike” but I’m no expert.

              • Dan replied to this.

                  Dan So to the question for the experts. I’m finding the scorching occurs after first crack, but interestingly this happens around 215c. This surprises me given most guides suggest final temps from the gene cafe of around 230-235. If I had run that on my roaster, I’d have charcoal. Could this be a machine specific issue? Or are most of the guides suggesting too high a temp for natural coffees?

                  I’m a fellow Gene with dimmer mode user. The temp you see on the Gene display is from the output probe. On mine, If that got to 230-235 I would probably have charcoal, if not a fire.

                  The trick to avoid scorching, in my opinion, is to be attentive to first crack and reduce the intensity of the heat with the dimmer as soon as it starts (i.e. when you hear the first pop, not when you have a rolling pop/cracking party). Once you learn to anticipate that (colour, temp reading, smell), you will be able to switch to dimmer mode and start to reduce the intensity slightly even before the first crack starts if you want to, without stalling the roast and baking the coffee.

                  For me it was helpful to think of the beans the same way as you make popcorn in a pan: as soon as you hear the first pop you need to significantly reduce the heat, or you will burn the popcorn. At this stage there is a lot of heat stored in the corn/beans + the vessel they’re in. They are very close to popping, and you need to pump in far less energy to keep the popping rolling. If once the first crack starts you keep pumping in high heat - you scorch the beans (or burn the popcorn).

                  • Dan replied to this.

                      Platypus

                      😂 I agree with your assessment that’s its rather toad like.

                      Prezes, your roast looks great, how far beyond 1c did you run it and what sort of temperature for the beans were you looking at?

                        @Doram that’s very interesting. So from what you are saying, you have the machine on full power until first crack(or slightly before that) than lower the intensity. Do you use a meter to measure the power the heater draws? If so how much do you lower the intensity? Are you using a 240v heater?

                        Lelit Elizabeth, La Pavoni, Niche Duo, Gene Cafe roaster

                          Doram

                          Thanks Doram, yes completely agree with your approach. The other point I’m learning is that stalling out the temp of the exhaust probe (i.e. Keeping the gene cafe temp stable to say 214) doesn’t necessarily stall the rate of rise of the beans themselves, as long as the exhaust temp is above bean temp, the bean temp will continue to rise.

                          Great to hear you also don’t go near 235.

                              oddbean @Doram that’s very interesting. So from what you are saying, you have the machine on full power until first crack(or slightly before that) than lower the intensity.

                              Correct.

                              oddbean Do you use a meter to measure the power the heater draws? If so how much do you lower the intensity? Are you using a 240v heater?

                              My heater is 240v. I don’t use a meter to measure the power, I do it by feel (conditions vary anyway, for example ambient temp or the bean used).

                              When I just started with the dimmer, I attempted to use it to keep the temp stable once the FC started (i.e. to stop the temp from climbing up, but not letting it fall either). This required a very minimal reduction of intensity - less than a quarter of a turn on my dimmer (full power is 12 o’clock, and I would probably take it down to around 9-10). However, This still produced some scorching and occasionally a darker roast than I was aiming for. So then I started dropping the intensity further (to around 7-8 o’clock). This lets the temp on the display drop a tad, but it doesn’t stall the FC so I still get it nice and rolling (I’m still pumping in heat, only it’s less intence so I’m slowing things down, making everything more gentle and controllable, [more forgiving if you like], with no scorching). I think it’s exactly the same idea as popping corn on a stovetop.

                                  Dan The other point I’m learning is that stalling out the temp of the exhaust probe (i.e. Keeping the gene cafe temp stable to say 214) doesn’t necessarily stall the rate of rise of the beans themselves, as long as the exhaust temp is above bean temp, the bean temp will continue to rise.

                                  See my reply to @oddbean above. I think this point is key: I initially tried to use the dimmer to keep the temp stable once FC started, but then learned that this actually leads to scorching and less control. I get better results by reducing the heat further and letting the exhaust temp prove drop a little just after FC starts. This way I don’t stall FC but get more control, no scorching and better roasts overall.

                                  • Dan replied to this.