Good lighter roast profile in city roast range ?

[BenN]

Updated fan curve to more speed in fist to move heaver beans and slow downs as loosing weight.

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Thanks Steve for hint! ( People should try his Hoo's test no. 3 profile! It's very impressive result. )

Below is Mexican with 004e

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And 004f ( longer/slower version ) with Brazil

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I haven't decided with profile give me a getter result, just yet.

Here is one with Steve's Hoo's Test 3 with Mexican.

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Great trace on profile. Based on thsi I might want lower preheat power further for my regular 100g batch..
Still lot to learn...

Those profiles are is on the first post, except Steve's one in this thread https://kaffelogic.com/community/viewto ... &t=87#p565 .

[Steve]

Thanks Ben, excellent progress.

I will add here what I have been playing with tonight. Version 4 of the "Hoo's test" from other thread.
Have increased the speed somewhat at the finish giving a much more pronounced first crack.
Smoothed out the fan profile.

Imported the latest smoothed fan profile into a modified Firestarter profile and it gives a really smooth looking roast.

Both roast 218C finish temp for a proper comparaison.

Thinking decline ROR not such a good idea on small air roaster in the finishing stage around first crack. If so it needs to be very gradual.

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[BenN]

Thanks Steve

It's very helpful.

I see fan curve is very similar to what I was using last roast.
I also find 004e ( shorter time) has pronounce FC sound compare to 004F ( longer roast version)

[Steve]

Matching a fan profile to desired roast profile for a specific bean is a deep rabbit hole! Still so much to learn and observe.

[BenN]

Uploaded new incarnation 004g and 007d on first post

007 series is more ( may be little excessive for some people) development time to aim for espresso and strong taste.

004 series is little more gentle, not quite light, but mid-light cleaner taste.

I use 004 for extropian variety or some case others if I want lighter one for filter and 007 series in different level for most of others ( Brazil, Honduras, Mexican, Bolivian, and so on) not only espresso but also filter.

[BenN]

Mexican beans 100g in and 85g out, uniform roast apart from very few odd cinnamon ones,
Stopped about 25% DTR and that was about 216C

Mexican uniform in colour

Mex.png (31.56 KiB) Viewed 6499 times

Same profile with Brazil Royal,, I somewhat had problem may be because ambient light breeze getting hit..
100g in and 86g out again stopped around 25% DTR but this time it ended around 217C
I see few uneven scorched beans in mix,

Slightly uneven in mix.

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I haven't brew them yet but I saw similar result with this particular Brazil Beans ( Royal) with last batch.
What may be a effective way to reduce this scorched beans? May be tweak fun speed?
Could just roast much righter?

I might try one I use for Ethiopian next time whcih is slower raise in initial curve.

[Steve]

Hey Ben,

I have see ROR and temp curve display the same behavior mostly when the fan profile (too low) is not a good match for roast profile. Particularly if the roaster is hot from high ambient temps and or back to back roasts this problem can be exacerbated.

Given you say there are some scorched beans in mix then fan could be a problem.

[BenN]

Hey Ben,

I have see ROR and temp curve display the same behavior mostly when the fan profile (too low) is not a good match for roast profile. Particularly if the roaster is hot from high ambient temps and or back to back roasts this problem can be exacerbated.

Given you say there are some scorched beans in mix then fan could be a problem.

Cheers, Steve. Indeed that was not the first roast of the day, I might has not enough rest time in between.
Here is a bit of comparison of fan speed with your Brazil profile. I see you have more speed at start. but looks like mid zone is almost identical.. I have more energy in that zone on time curve so may be need little more air speed in there.

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This is comparison to Firestarter, May be follow that mid line while keeping start up speed, could be a next try.

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Thanks for advice, again.

[kaffelogic]

What may be a effective way to reduce this scorched beans?

Hi Ben,
In my experience there are a couple of causes of scorched beans. As Steve has pointed out, insufficient air at the start of the roast is a possible cause. At its most extreme some beans will get trapped in the air inlet for the early part of the roast and can get burnt. The typical result is a few black beans speckling the roast. At the level you are seeing it (scorched, not black) the cure could be slightly more air at the start, less heat at the start, or smaller batch size - whichever you prefer to tweak. Trying a smaller batch is quick and easy because it doesn't require editing the profile.

I believe that it is also possible to see scorching by going too fast after first crack (for the particular beans). This will be even scorching that applies to most of the beans. After first crack the beans have a much lower density and heat conduction is slower. This means that it will take longer for heat applied to the outside of the bean to penetrate to the inside. Too much applied heat will scorch the outside without reaching the inside. Shortening the roast without changing the profile might lead to under-development. Slight flattening or lowering of the profile curve after 180 deg C can help with this issue. A smaller batch size will not cure this issue - it could actually make it worse.

[BenN]

Thanks Chris for very helpful advise.

I normally use Cerrado variety of Brazil and Royal is my fist time, It indeed seems to be reacting bit different way.

Always something new to lean or try. Challenge is good and fun.