# Long immersion brews & grind size and brew ratio



## the_partisan (Feb 29, 2016)

I'm curious if anyone has compared how extraction yield in long immersion brews (12 mins+) correlates to grind size and brew ratio. My thinking is that a lot of the extraction in this type of brews happens via diffusion and the concentration gradient (which is mostly determined by the brew ratio) might affect extraction a lot more than grind size. So if you want to do a quite long immersion brew, a fairly coarse grind size might give you similar results to a finer grind in terms of EY at same brew ratio. I might be totally wrong of course, but I haven't noticed a huge difference in taste when changing grind size significantly with immersion brews, except the amount of silt in the cup. I'm curious if anyone has actually tested this?


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## MWJB (Feb 28, 2012)

Temperature is important, if you grind coarse (say proper coarse ~1200um?) on a declining temp steep then extraction will be limited in the time it takes for coffee to cool & still be at drinking temp.

Well insulated brewer &/or big brews allows you to go coarser.

Once you are fine enough to hit the extraction you want, in the time you want, then going finer just increases silt.

For immersions, brew ratio doesn't impact on immersion EY yields within reason (say 55-75g/L, at same grind size, brew water size & steep time). Going crazy short (Aeropress espresso type brew ratios) will probably impact on EY because the small amount of brew water will lose temp quickly to coffee dose & brewer.

In most immersions, in single wall, small brews you're not even close to being limited by concentration equilibrium. In a small FP/cupping scenario a bunch of tests saw me average ~22%EY at fine drip/espresso grind. Finer grind could make this possible in 10min, more towards drip, maybe 20min.

I have instances where going superfine actually dropped EY...didn't pursue it, so not sure it is trend.

Now go medium drip, like your V60 grind, and a double wall steel brewer and it's easy to hit 25-26% in 40-60min.

Brew in an Ibrik and 27% (at 100-150g/L) is plenty achievable in 10-20min (boiling water into 100ml ibrik, on to low heat on electric hob, so ~80c upwards during contact time).

If concentration gradient was limiting EY, you wouldn't be able to keep bumping up the EY with hotter, longer steeps.


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## the_partisan (Feb 29, 2016)

Thanks for the info. I've been using fine drip and long brews but was thinking to use coarser grinds to get clearer cups. I would be curious to do some tests, i.e. same brew ratio, both brewed 20 mins at two different grind sizes. I haven't found quite a good way to measure TDS for immersion brews without expensive syringe filters though, even Aeropress seem to have a quite a bit of undissolved solids. Maybe Prismo helps in this aspect?


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## MWJB (Feb 28, 2012)

Prismo may be better...not sure it's good enough to negate a syringe filter.

No Clever Dripper? Or, is it possible to use the Moccamaster for a smaller (300-400g), full immersion?


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## the_partisan (Feb 29, 2016)

Nope don't have a Clever or Bonavita. I can try with the Moccamaster filter holder though, it's also a Melitta type cone. Do you do any agitation after pouring with a Clever/Bonavita? It's also probably not the best insulated brewer. Also I guess it's not needed to measure the final beverage weight?


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## the_partisan (Feb 29, 2016)

I did one brew now as above, 2+0 on Kinu M47, 13.7g dose, 250g water, steep for 12minutes covered with a plate then open valve. Drained in about 2 min

214g beverage out, 1.23% TDS. VST tells me this would be 24% EY but I highly doubt it.. Taste was ok but had some astringent notes, not as clean and defined as my regular Moccamaster brews with same beans (but different grinder and coarser grind) which were 19-19.5% EY with same ballpark TDS and same brew ratio, but bigger (27.5g:500g).


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## MWJB (Feb 28, 2012)

the_partisan said:


> Nope don't have a Clever or Bonavita. I can try with the Moccamaster filter holder though, it's also a Melitta type cone. Do you do any agitation after pouring with a Clever/Bonavita? It's also probably not the best insulated brewer. Also I guess it's not needed to measure the final beverage weight?


A quick, gentle stir at fill. No need to measure final beverage weight for immersion EY, but you can to check whether your favourite mug will overflow


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## MWJB (Feb 28, 2012)

the_partisan said:


> I did one brew now as above, 2+0 on Kinu M47, 13.7g dose, 250g water, steep for 12minutes covered with a plate then open valve. Drained in about 2 min
> 
> 214g beverage out, 1.23% TDS. VST tells me this would be 24% EY but I highly doubt it.. Taste was ok but had some astringent notes, not as clean and defined as my regular Moccamaster brews with same beans (but different grinder and coarser grind) which were 19-19.5% EY with same ballpark TDS and same brew ratio, but bigger (27.5g:500g).


24% sounds feasible, I aim around 25% for Clever/Bonavita/Aeropress, a couple of % less with


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## the_partisan (Feb 29, 2016)

MWJB said:


> 24% sounds feasible, I aim around 25% for Clever/Bonavita/Aeropress, a couple of % less with
> 
> I have a bit of hard time believing it was a whole 5% EY more than my drip brews though
> 
> ...


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## the_partisan (Feb 29, 2016)

I did a second brew now, with significantly finer grind (1+6 on Kinu)

Same dose, less g out this time as it took forever to drain fully, (209g) and TDS was 1.26%. So slightly higher but not by much. Taste was really astringent and not enjoyable at all. I'm not sure why this is the case since I've had delicious Aeropress brews at 1+6 brewing inverted for 10-15min at same dose/water amounts, but with different beans..


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## MWJB (Feb 28, 2012)

the_partisan said:


> I did a second brew now, with significantly finer grind (1+6 on Kinu)
> 
> Same dose, less g out this time as it took forever to drain fully, (209g) and TDS was 1.26%. So slightly higher but not by much. Taste was really astringent and not enjoyable at all. I'm not sure why this is the case since I've had delicious Aeropress brews at 1+6 brewing inverted for 10-15min at same dose/water amounts, but with different beans..


I'm not sure the astringency is a result of increased extraction (increase here looks pretty negligible), but maybe down to increased tiny particles (from grinding finer) being flushed through the deeper (V shaped) grounds bed?

The balance is grinding fine enough so that you get desired extraction, but coarse enough to limit off flavours from fine silt.


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## the_partisan (Feb 29, 2016)

I also didn't do any stirring in either brew, which maybe affected the evenness. The temperature might also be a factor - the resulting brew was significantly cooler than my Aeropress brews, in fact it was just barely warm.


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