# Solubility of beans



## Step21 (Oct 2, 2014)

Or how easy they are to extract. A few questions....

Given the same brewing parameters, i notice for instance that African beans tend to produce higher TDS readings than say South American.

Is this primarily a function of origin/varietal?

Does the type of processing have an effect? e.g will a natural process produce a different level of solubility than say a washed (of the same bean)?

Does the level of roast have an effect? For the same coffee will a darker roast produce a higher TDS than a lighter roast?

I also notice that decaf beans seem to be very low (presumably due to the decaf process?)

Adjust brew ratios to compensate?


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## foundrycoffeeroasters.com (Jun 19, 2014)

If the beans have been roasted properly, they should be soluble, regardless of the varietal/origin etc. The roasters challenge is to work out how to get the beans both flavoursome and soluble. Lighter roasted beans will usually need to be ground finer and/or brewed at a higher temp to get the same level of extraction as a darker roasted bean when using the same method.

If you're having problems extracting the coffee, chances are it's not been roasted well enough.


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## MWJB (Feb 28, 2012)

Step21 said:


> Does the level of roast have an effect? For the same coffee will a darker roast produce a higher TDS than a lighter roast?


Hard to differentiate 2 factors here without simultaneous identification of grind profile & a standardised solubility test, but in percolations you not only have the ease with which solids are extracted from the coffee, but also the fact that the same bean roasted darker will break up less predictably producing more fines & lower average grind size at a common grinder setting. So more fines my extract further themselves, but also by slowing the flow may lead to higher extraction of the dose overall.



Step21 said:


> Adjust brew ratios to compensate?


A nominally developed coffee should be extractable, certainly by drip, by grind adjustment retaining the same ratio. But, a darker roast may be more intensely flavoured and might require a lower brew ratio, conversely a lighter roast may be better with a higher brew ratio.

If I just can't get an immersion into my preferred zone (52-56g/l & 23%), then I aim for a lower preference point at a higher brew ratio (65-70g/l & 19-21%).

Definitely getting some higher EYs from Colombian, Bolivian, El Salvadorian coffees, as well as Kenyans.


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## Step21 (Oct 2, 2014)

foundrycoffeeroasters.com said:


> If the beans have been roasted properly, they should be soluble, regardless of the varietal/origin etc. The roasters challenge is to work out how to get the beans both flavoursome and soluble. Lighter roasted beans will usually need to be ground finer and/or brewed at a higher temp to get the same level of extraction as a darker roasted bean when using the same method.
> 
> If you're having problems extracting the coffee, chances are it's not been roasted well enough.


Thanks. I have noticed that the African coffees i've had from yourself at Foundry, especially the Kenyan and Tanzanian have been very soluble (as well as very tasty!) I was grinding them considerably coarser than my "usual" and still getting good extraction.

I don't go in much for dark roasts but i have one at the moment and i have found i can't get my immersions up to my usual EY preference at the lower brew ratio as Mark describes below. But it does perform well at a higher brew ratio (66g/l) hitting a lower EY of 21.5%

Can i ask what factors in the roasting process affect solubility?


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## garydyke1 (Mar 9, 2011)

Step21 said:


> Does the type of processing have an effect? e.g will a natural process produce a different level of solubility than say a washed (of the same bean)?


The presence of silverskin/chaff can have an effect on extraction in various methods.


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## foundrycoffeeroasters.com (Jun 19, 2014)

Step21 said:


> Can i ask what factors in the roasting process affect solubility?


I guess that's the essence of it all from our perspective and it varies loads depending on the bean so difficult to say. As a general rule, we're aiming to have the beans in the roaster for the shortest amount of time that we can whilst developing the flavours and getting the solubility we want. In the end, it's all about tasting, testing, roasting, tasting, testing.....you get the idea.


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