# Why do kenyan beans blacken up so quickly?



## Going banana's (Apr 8, 2014)

ok, maybe it's just me but whenever i roast particular african beans, (sl28 Kenyan's, malawi geisha's), they turn much more blacker than i want them to. By the time first crack starts theyre already dark, at the end of fc theyre getting blackened but not oily.

Ideally i'd like to hit a light brown colour to preserve the light flavours but i'm starting to think this is impossible with certain beans.

most other beans behave themselves so is this a normal characteristic of some african beans?


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## froggystyle (Oct 30, 2013)

Whats your roast profile?


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## Going banana's (Apr 8, 2014)

these are bean temps. its usually about:

100c increasing to 150 in 4 minutes,

then a 15c/min ramp to 210c at 8 min,

then increase to 220ish and hold at 9 minutes.

sometimes i go up to 230-235c at 10 min if its going a bit slow.

fc usually occurs around 9-10 min and i'll normally finish about 12 min.

perhaps my temps are a bit high but ive been getting ok results with other beans so never changed to a lower and slower profile, its only the kenyans etc that i get the blackening.


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## froggystyle (Oct 30, 2013)

Have you had a look on this link for the beans your roasting...

https://creator.zoho.com/davec_coffeetime/coffeetime-shared-roasting-log/#View:Roast_Log_Information_List_View_detailed

Never done African beans so cant compare against any of my notes!

Davecuk will be better placed to answer i reckon.


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## DavecUK (Aug 6, 2013)

> these are bean temps. its usually about:
> 
> 100c increasing to 150 in 4 minutes,
> 
> ...


That's a very aggressive roast profile... aim for a 15m 30s roast and lower max temp try 234 max, but take longer to get there. it's difficult becuase all roasters are a bit difficult, I don't know if yours is a 230V or 240V element, is it modded or what...+ what is your mains voltage?


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## Going banana's (Apr 8, 2014)

im just using a heatgun/bread machine with the temp probe in the bean mass, a faster profile than the gene is normal i think for this setup. i favoured the fast rise, slow finish profile as i read that the less time spent between 150c and first crack the better. i might try a lower, slower profile on a test batch to see if the blackening still occurs, but i think its just the nature of kenyan beans and i'll never get a light coloured roast out of them. however ive read on a few forums that because kenyan beans are so hard and big they need blowtorching/ an aggressive profile to reach fc in a reasonable time.


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## DavecUK (Aug 6, 2013)

Hmmm.............


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