Insulated Corretto Pan - first experiences :-)

[DesigningByCoffee]

Following some great ideas from Mal, Ive now insulated the pan on my corretto (see pics) and thought others might be interested. Ive used a $10 fire blanket from Bunnings and some wire to strap it all together, and even sewed up the underneath with wire to give some insulation to the base. I had to do a couple of small wire loops over the pan latch tabs, just to stop it sliding down when the pan is clicked into place. I ended up removing the element, as it was getting a bit caught up - but breads unlikely to ever be cooked again in this puppy!
And the results are quite startling! Im already used a DMM and a corretto cover, which have been giving me some really nice, consistent roasts that are starting to taste great in the cup. But the insulated pan adds an extra dimension - even if its bit hard to quantify. First roast using it today, same technique/settings as I have been using sans insulation, and the profile, while similar, seems much smoother. It took slightly longer to warm up, but then built up much more evenly without any spikes.
And the smoke! (not sure if this is a good thing ;D) In previous roasts, I might get a few wisps just before 2C - today I had gentle wafts from around 100 degrees and continued building right to the end at 222. Good rolling 1C - and not a hint of charring - very even roast. I can only put this down to much more radiant heat off the metal - maybe giving a fuller, deeper roast? Same time frame - but seat of the pants seems like a real winner
Ill keep you informed how it tastes in about a week!
Matt

[Dimal]

Re: Insulated Corretto Pan - first experiences :-)

Gday Matt...

Your observations are pretty much the same as mine mate. The insulation definitely smooths out the entire process quite a bit and in the case of my particular setup, Im able to reach very close to 1st-Crack at the lower fan speed before needing to step up to the higher speed on towards 2nd-Crack.

Even though the fan speed needs to be increased to push enough heat into the Corretto, the output temperature needs to be increased only marginally. When its all said and done though, I really enjoy the end results more, in the cup. Seems to be a much more balanced result overall, more body and less emphasis on acidity while the overall sweetness seems to be improved too.

Have no answers re: the extra smokiness though ;D

Have fun mate... 8-)

Mal.

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

Have no answers re: the extra smokiness though

Thanks for your input Mal
Did another batch today, and much less smoke - so Im putting it down to the higher retained temperature of the pan burning off 6 months worth of residual coffee oils!
Another good roast - though did a hotter preheat (150) and slightly earlier ramp to 1C - and got some minor tipping. But still worked beautifully smoothly
Im not sure about all the heat vs fan speed juggle - Im using a budget gun (2000w Ryobi) and adjusting the height only. But I have developed a double chimney (tomato can on the lid, plus 3 inch extension of the gun which basically allows overlap in most roasting ranges , preventing wind blowing the heat away. So my basic working height has the tip of the HG about 300mm off the bean mass…
The journey continues!

[Dimal]

Re: Insulated Corretto Pan - first experiences :-)

Im not sure about all the heat vs fan speed juggle - Im using a budget gun (2000w Ryobi) and adjusting the height only.

The Makita HG I eventually found, has a nice large heat output adjustment wheel that is easy for me to manage as opposed to juggling the height of the HG :P
I used to do this before and it worked ok, not as repeatable as variable heat though (for me)....

Mal.

[sidewayss]

Re: Insulated Corretto Pan - first experiences :-)

Im able to reach very close to 1st-Crack at the lower fan speed before needing to step up to the higher speed on towards 2nd-Crack.

Hi Mal,

Ive got a question regarding the ramp up to second crack.

Currently i have a roasting profile that has a steady drying out phase til 150 deg, then i ramp up heat til before first crack, then i back off the heat to allow the exothermic reactions of the beans to keep the increase in temperature in momentum and then aim for approx 2-4 degrees per minute rise til second crack.

What i dont understand is your slight increase in output temperature and increase in fan speed.
If fan speed is increased, then the temperature setting on the gun must decrease?
Presumably if both fan and heat setting increases then there would be a uncontrollable roast running away from first crack straight into second crack.

Going to get a fire blanket today after finishing off Mals fibreboard coretto cover project and then hopefully post some good results/disasters  ;D

So how did it eventually taste using the blanket?

This will keep me busy til the next phase, the KKTO. 

Gary at G

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

ramp up to second crack

Been wondering the same Gary - I ramp up to 2nd from about 130-140 - but Id be interested to know what technique Mal uses too…
Just as an aside - with a few more roasts with the insulated pan I might need to pull my roast earlier with the blanket in place - the 222 degrees now seems a little overcooked - think it just retains much more momentum just heading into 2C >

So we roll on!
Matt

[Dimal]

Re: Insulated Corretto Pan - first experiences :-)

Hi Guys...

The Makita HG I use actually uses a closed loop control system to manage the Output Temp. When switching from Low Fan to High Fan or vice versa, the Output Temp does shift a little but is easily brought back "on profile" by readjusting the controller wheel. Its not difficult or I wouldnt be able to do it.... :P ;D

Agree with you there too Matt.... Definitely changes the thermodynamics of the system when the pan is well insulated. The recent additions that Andy has made to the Roast Monitor software makes this easy to manage though, by tracking the "Rate of Change" trace on the chart. An excellent update for we home roasters I reckon... 8-)

Mal.

[mobbarley]

Re: Insulated Corretto Pan - first experiences :-)

Dont breathe too much of that smoke (I might be a bit late)!

Wrapped my Quest in a bunnings fire blanket and did a test before roasting - didnt see any smoke.

Obviously I didnt get it hot enough as it wafted white smoke when I did a roast with it (didnt smell too strong over the bean drying smell - hard to notice). Luckily I didnt stitch it up so I could just pull it off without interfering with the roast. It might have stopped smoking but I couldnt step away from the roaster and didnt want to breathe it in.

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

Hi mb
I dont think mine was smoke from the fire blanket - it was when I tried to use a woolen blanket though! ;D
It only happened the first batch, so I think it was old built up coffee oil burning off - havent experienced that level of smoke since, just the general bean waftings.
And the only discolouration on the fire blanket is not from burning, but slight smoke staining around the gaps - so I think itll be a good long term solution.

Matt

[sidewayss]

Re: Insulated Corretto Pan - first experiences :-)

Thanks to DBCs fire blanket and Mals inspired fibro coretto cover, together with some minor tweaking of the coffee roasting profile, the coffee is tasting better than ever.

With those additions, I have reduced the setting on the heatgun by up to 30 degrees for the same roasting time.
ie. Prior to mods: 420 deg. 1st C to 2nd C temp: 360 deg.
After mods: 390 deg. 1st C to 2nd C temp: 330 deg.

I can only presume the decreased requirement of heat input and heat retention helps in boosting the quality of the end result. The appearance looks better, I still get some divots but hardly any tipping.

It tastes better now in the cup, and my friends and workplace agree.

Gentlemen, my thanks for you sharing your tips and advice.

Gary at G

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

Great to hear Gary!
It certainly gives a smoother, more controllable temp rise (therefore better profile) and requires much less heat input, which must be gentler on the beans. Ive certainly found it sweeter and with more body in the cup too.
Ive had some tipping in the past - but mainly when Ive tried pre-heating the pan then dumping in cold beans. I have now pretty much eliminated that now by doing a gentle pre-warm (up to 30 degrees) for the first 2 mins of erratic mixing (my BM is still on a standard dough setting) then giving a consistent heat input till 150 degrees (which takes about 6mins) then ramping up slightly (by dropping my gun by 2cm) till 195 (about 4 mins later). At 195 I drop the temp input significantly (lift gun 5cm) to reduce temp climb to just above stalling point, drop again slightly at 200 (1cm), then again at 205 (by another 1cm - 205 seems to be where the rise can start to run away again) - this input then gives a nice gentle climb all the way to 2c (222 deg in my setup), all up which takes about another 4 mins. Bout 17-18 mins all up.
This last few batches has been quite amazing - and no tipping!
Look forward to hearing your cupping experiences on these new batches

Matt

[Dimal]

Re: Insulated Corretto Pan - first experiences :-)

Great news Gary... [smiley=thumbsup.gif]

Just need to become familiar with the (slightly) altered thermodynamics of the system and therell be no turning back.

Good stuff mate... 8-)

Mal.

[sidewayss]

Re: Insulated Corretto Pan - first experiences :-)

Theres certainly no turning back Mal. 

The KKTO arrives later in the week, so the coretto will have a holiday while i get adjusted to the new arrival.

Once things get sorted out, Ill compare the roasts from those two.

Thats what i do too DBC, gentle heating of the beans to stabilize moisture levels of the beans at 50 deg for 5 minutes, then start the roasting proper.
What i do though is start backing off the heat at 185 deg, which is about a minute before 1st crack so that it eases into the exothermic reaction and the profile is more controllable for the 2-3 deg per min from there til 2nd C.
I dump at 214 to 215 deg to give me maximum sweetness according to my palate.

The pour coming out of the spout looks lazier, more syrupy, both on the Miss Silvia at home, and the "brown bertha" San Marino at work.
Theres more intensity in the flavour and seems to have extra creamy mouthfeel.

Current roast times are at 16-17 minutes.
Ill try a slower gentle roast tomorrow, stretch it out to about 18-19 min and then taste.

Whats your colour scale after dumping at 222 deg DBC?

Gary at G

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

Whats your colour scale after dumping at 222 deg DBC?

Hi Gary
Agree with the syrupy pour
I would say CS8-9 (that bottom pic this page is pretty standard). Im sure it has to do with the probe placement and bean mass etc.
In flavour (which seems a bit more reliable to compare) I found that from 219-221 there were nice aromas but slightly light-on in body and a slghtly sour taste in a doppio (all I drink really that can give me a full flavour analysis) - but hit that magic spot at 222 the sourness went away, body fullness & depth increased and aroma in the bag improved.

Current roast times are at 16-17 minutes.
Ill try a slower gentle roast tomorrow, stretch it out to about 18-19 min and then taste.

Ive tried some slightly faster roasts recently between 1C-2C (not reducing temp again at 205) which would only take about 4-5mins - but started getting divots - so slowed it back down.

BTW i think im confused in my terminlogy - what is te difference between tipping and divots? :-?

Happy roasting today! Im done till next weekend

[DesigningByCoffee]

Re: Insulated Corretto Pan - first experiences :-)

BTW i think im confused in my terminlogy - what is te difference between tipping and divots?   

Just done a search - and I see!
So - Ive had lots of divots - but no tipping!

As to the differing temperatures between correttos, Ive just had a thought.
I use a non-adjustable Ryobi 2000w gun flat out for all my roasts, just adjusting the height. I have a tomato can chimney on my lid, plus a 3 inch extension on the gun. The main working height I use is quite high, with the end of these two units basically lining up. This means that the gun element is about 300mm off the bean mass, as opposed to an adjustable gun sitting on/into the actual lid (element height about 100mm above bean mass).
Im wondering if, despite a similar temperature rise profile, my setup gives a slower browning on the outside of the beans (and subsequently later 2C when the outside hardens/splits again) but allows the inside to heat up more, raising the overall bean mass temperature higher - hence my higher readings?
When starting I saw lots of 215-218 readings, which a use as my benchmark for a while - but in espresso was completely undrinkable in the DBC house! So I wonder how much reading error/difference is actually in the DMM/setup, and instead whether the temp of 2C can be a variable between the outside browning and inside temp?
Just thinking aloud :

Matt