# Avoiding Stalling or Baking on a modified Gene Cafe.



## Rob1

I've been roasting coffee for just over a year. I don't drink a whole lot of coffee (though my consumption has more then doubled since buying the Brewtus) but since Feb 2014 I've gone through about 20kg of Greens. For less than half of that I've been roasting with a modified gene cafe (240v element with dimmer mod).

I've tried a number of different profiles all with varying degrees of success; I've had a few roasts that were bad and a few that stood out as good, but mostly they've been underwhelming.

Lately I've been using about 900 watts for 1.5 minutes (temperature gets to approx 100c) before pushing up in stages of 1000 and 1100 for 1.5 minutes each, and finally 1200 when the beans turn yellow. I've been using this for beans that were very dense as I was worried about underdevelopment and wanted to get the beans warmed up to a consistent temperature before pushing to first crack.

Tonight I used the same profile on a very open looking bean from Bali and it appeared to take to the profile well, hitting the first pops of second crack 11.5 minutes from the beans starting to pale and expand, and 8.7 minutes from turning yellow. There were never any signs of tipping or scorching at any point in the roast. Time from yellow to first crack was 5.5 minutes (would prefer 4-5 minutes). First crack lasted 2.5 minutes exactly (from very first pop to very last). My problem with this roast (and I haven't tasted it yet so this is all theoretical) is that the time from the end of first crack to the beginning of second was 42 seconds.

So I'm worried that I'm baking the coffee. I read Matt Perger's article on roasting in which he refers to the "flick of death" as being an increase in the rate of rise after first crack.

My logic was that the less time spent at +160c the better as that would avoid caramelizing too many sugars, this is why I was trying to end the roast at my desired depth quickly after first crack (while stretching out first crack). Perger suggests a slowing of the rate of rise produces a sweeter cup with more complex flavours and my profile will result in a coffee that tastes flat and dull.

Looking at my recordings I see temp was rising at a rate of 5c/min going in to first crack. I cut power to 1050 about 15 seconds after the first pop and from there I can estimate bean temp.

According to my information first crack starts at 205c, is underway at 212c and finishes at 219c.

First crack started at 13.5 mins and hit rolling at 14.5 mins, indicating a rate of rise of 7c/min. From 14.5 to 16 minutes (when first finished) the beans gained another 7c (a slower rate of rise).

However second crack starts at 234c. So 219c to 234c in 42 seconds is a ROR of over 15c/min.

Obviously this indicates a huge "flick of death". More like an uppercut. I'm guessing this is made possible because the beans have lost moisture and they take on heat a lot easier. Anyway, my question is, how do I avoid this when roasting dark? Is the only option to have a much larger drop in temp (power) at rolling first, rather than a slight drop at the start? Logically I should be able to stretch out first crack and achieve a slower ROR this way, but I'm worried about caramelizing too many sugars by having a long time between first crack and the start of second after reading this: http://www.coffeeshrub.com/shrub/content/stretching-out-roast

The article above has really helped me bring my roasts along and I've been able to manipulate the beans to how I want them with some good success, making me think the information here is quite reliable.

Can anybody chime in here with their experience of using the gene and avoiding stalling/baking. What kind of power do you apply at the different stages?


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## hullcity

My experience is mostly with Brazils and C/S American hard beans. I just heat up the beans at 1200W from room temp to first crack, stabilise at that temp by dropping the power down to around 1100W until 1 min into first crack, then drop the power again to 1000W (sometimes a touch lower) to reduce temp steadily by 5 degrees or so. I tend to roast to the first pop of 2nd crack, hit stop and cool in the gene. With the Brazils I drop the temp by only a couple of degrees.

First crack lasts around 1:30-1:45 min and second starts about 2:00-2:30 min after the end of first.

An exception to this is Monsooned Malabar, which I heat up to 150C (1200W) and keep there for 10 min, before ramping up again at 1200W to first crack, at which point I drop the power to stabilise the temp. This I roast further until about 30 sec into second crack, when the beans are showing an oily sheen. The drying at 150C really made a difference for this bean, without it I really struggled with MM in espresso!

I tried the 10 min drying with Brazils but I found this detrimental.

I've tried using temp stages during the roast a few times but with no real success. I think without having access to the bean temp it is not worth worrying about ROR etc. Keep it simple and let the gene do its stuff and you shouldn't have any problems with baking.


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## DavecUK

Jesus talk about articles and TMI on the web totally fecking up you're roasting. Forget the web articles, go back to basics, speak to someone like @Mouse, who has my old Gene now. One study you refer to uses a probat sample roaster with an 80g batch and 8m (approx) roast times. this can't and never will translate to your Gene Cafe.

With the power consumption figures of 1200W, either you have really good mains voltage, are not using the power meter I suggest (other common ones can be quite inaccurate and under read the watts). In summer I was able to roast in my unheated workshop with as low as 1150W in colder weather 1180 and in super cold conditions perhaps 1200 or a tad more. The gyrations your performing in the early part of the roast profile are not helping you. Simplify back to basics as much as you can and work with your roaster, not against it. Think hard about the physics of the roaster and why some of the things you're doing may not make sense.


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## hullcity

I think the thing that has helped my roasting efforts the most has been keeping the temp under control at the start of first crack. Previously I used to have a set temp in mind and heat to that point even if first crack was underway, which could be a few to several degrees higher. It's that window between first and second cracks which needs the most attention and fiddling with.


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## DavecUK

hullcity said:


> I think the thing that has helped my roasting efforts the most has been keeping the temp under control at the start of first crack. Previously I used to have a set temp in mind and heat to that point even if first crack was underway, which could be a few to several degrees higher. It's that window between first and second cracks which needs the most attention and fiddling with.


Amen to that


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## Rob1

Thanks for the tips guys.



DavecUK said:


> Jesus talk about articles and TMI on the web totally fecking up you're roasting. Forget the web articles, go back to basics, speak to someone like @Mouse, who has my old Gene now. One study you refer to uses a probat sample roaster with an 80g batch and 8m (approx) roast times. this can't and never will translate to your Gene Cafe.
> 
> With the power consumption figures of 1200W, either you have really good mains voltage, are not using the power meter I suggest (other common ones can be quite inaccurate and under read the watts). In summer I was able to roast in my unheated workshop with as low as 1150W in colder weather 1180 and in super cold conditions perhaps 1200 or a tad more. The gyrations your performing in the early part of the roast profile are not helping you. Simplify back to basics as much as you can and work with your roaster, not against it. Think hard about the physics of the roaster and why some of the things you're doing may not make sense.


My voltage tends to be about 248-250v. Rarely dipping below there. The reason for the lower power at the earlier part of the roast was that I was getting a lot of scorching when just using 1200w from the start.

I'm probably not using the meter you advised but the draw when the dimmer is out of the circuit reads as 1320 (from memory), if that's any use. I'll see if there's a way of confirming the accuracy.

I know my roaster is completely different, and I'm not trying to replicate total roast times I see in other profiles. But chemically and physically aren't beans undergoing the same or very similar changes? For example, shouldn't the length of first crack or the length of a drying phase at x temp carry over from one roaster to another? I'm trying to focus on bean temp, but the info I have say second crack starts at 234c so my temp readout on the gene needs to be above that after first, meaning first crack needs to occurs at a higher temp than 236c (as in my last roast) if I want to achieve a slower ror.

I've tried just doing the basic 1200w and dropping power at FC and the results were worse than I'm getting now. I've become entirely focused on controlling power and temp during and after first (after gently introducing the beans to full power) and will try another roast tonight with just tossing them in to see if that helps control the end of the roast somehow.


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## DavecUK

Some power meters under read by 6 Volts, that's around 40W different on the power measurement, this many not seem a lot, but it is. It's the difference between summer and winter roasting. Also the element can run really hot if you put too much power through it, so above 1180W in summer (on an accurate power meter) can cause the element to switch because of overheat switching, regardless of the exit temp shown on the display. You may not be listening for this and could be getting it.

Temp isn't that important, well not the display on the Gene, it's only to tell you when you are getting near the point of element switching. Also by the time you see a "particular" reading on the dial, it's already way too late. A bean that expands more will show lower exit temps, but often have higher chamber temps. Roasting less than 250g usually isn't good. I used to set the temp dial to 245, just so that the genes in built temp control would never be reached, but if I keeled over and died, hopefully the thing wouldn't catch fire.

I then roasted on power alone, which gives a totally repeatable roast. The display was simply a guide for "problems", not a mantra for the roasting profile. if you know the environmental temp, then you know the max initial power you can supply and the power required for any particular roast profile to be achieved. if you use too much power (at any roast phase), it doesn't matter what the exit temp on the gene shows, you can still scorch the beans. The other thing is to forward think the roast, rather than try and correct later for a mistake made perhaps 5 minutes earlier.

With the CBR1200, mine is modified with power control, after the first roast when she is completely stable, I can repeat a roast exactly, almost to the second, by simply applying (reducing or increasing) the same power at the same times during subsequent roasts of the same bean. I can also roast quite a bit faster than the stock CBR1200, using lower temperatures...but you have to be brave and trust the numbers on the power meter.

roasting by power (adjusting for environmental air temp) is the only totally repeatable and shareable way for electric roasters (because voltage varies).


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## Rob1

Thanks Dave. I can confirm I've heard the element switching on and off when the wattage reads over 1230. I assumed I was triggering some kind of safety feature related to over heating and stopped using that much power unless I desperately needed to push the temp up quickly and only then used it for half a minute out of fear of causing damage. When that happened my results were the worst anyway (I think roasting the acids out before 1st) so it's only something I do now if I want to reduce time between yellow and first to experiment.

I'll revisit this thread before starting my roast tonight.


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## jefferson17

Here's what I'd recommend. Start with a good pre-warm - to about 400 F, then charge (drop beans). Kill the heat for 1 min then set heat back to high. You will want a continuous rise in temp for a few min. Once your ROR tops out (probably 2-3 min) you then wish to try and maintain a slow and steady reduction in ROR for the remainder of the roast. It may be a bit tough to get that right but if you can adjust your heat/air flow, you should get a much better result. Right now, there is too much baking, and not enough roasting. A high initial temp is pretty essential to getting you the desired and more optimal end roast development.


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## Rob1

Thanks for the input but I can't imagine that would be effective in a gene, though the advice looks good for traditional drum roasters and other setups.

The high initial temp is the important thing for a good roast. The gene has a good heat up time (with proper voltage) and produces a naturally declining ROR until first crack even when running on full power. The bean mass probe I installed indicates cooling is rapid, with the beans falling below 150c in about 3-4 minutes. It consistently takes the beans 5 minutes to pass the 150c mark and I now aim for a 16 minute roast time for sweetness and development rather than the 12 minutes I was aiming for at the time I created this thread.

My heating element wasn't properly sealed and it would begin cycling on an off a round 220c and slowly rise from there. After fixing it I drop the power down (from full) at about 175c or 185c bean mass depending on desired final temp when previously I was dropping the temp around 160 or 165 which was too early into the roast. The gene responds very quickly to power changes and pre emptying isn't really necessary unless your ET is very high.


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## Robbo

I tend to keep the dimmer switched out until at 1c which usually sits around 1250w

When I switch it in the power drops to around 1150w and that tends to stabalise the temp for a minute or so. I may then reduce to 1000w to lower temp a couple of degs until end of roast. Which for me is usually just before 2c although I mainly go by colour. Sometimes it drifts into 2c during cooling. (Gene cooling cycle)

The 1st roast usually takes around 16-17 mins and subsequent roasts around 14-15 mins.

I have had some good results using this method although I always like to hear how others roast with their modded gene.


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## Rob1

I hit second on 16 minutes with the Ethiopian I just roasted but with the Panama I was about 1 minute away finishing at 229c. I used the same profiles both times but I was roasting at 250v with the Ethiopian Vs 246v with the Panaman.

Would be interesting to know your temp readout at first crack. Mine is always just above 230c. I bring the dimmer in by bean temp but the readout on the gene is usually 220c or a couple of degrees above after around 6 minutes.

For new users, knowing the heat up time of their roaster with a 250g batch size may help in determining when to use the dimmer.


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## hullcity

Thanks for the info guys. I'm still roasting at around 1200W up to first crack, then drop the power to stretch development out and hit cooling just before second crack. For softer beans I also try 1150W.

Temp at first crack is between 232 to 238C (gene readout), depending on the bean.

Heat up with 250g beans (at 1200W) to 220C is almost always 11 min. Rob1, 6 min seems really quick, have you got a flamethrower attached to your gene?


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## Rob1

The 1200w is the dimmer out, right? I'm pulling 1250w or even 1330w measured with a Prodigit 2000MU power and energy monitor (the recommended model from coffeetime wiki).


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## hullcity

Nah, 1200W is with dimmer on. I have the 230V model (I live in France), but the voltage around these parts is usually in the upper 230s and can get up to 245V! It fluctuates quite a lot such that I have to keep an eye on the plug meter and make little adjustments on the dimmer during the roast. Without the dimmer I'm at over 1300W during the summer, less in the depths of winter when the voltage goes down to 230.


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