I recently bought a hario cold brew bottle and my head began to spin about how much difference a high quality grinder does when the brew time is long? Today I use a Wilfa Svart Aroma conical grinder for aeropress and brew (waiting for lagom p100). When tasting light roast grinded with the ek43 at Tim Wendelboe, and then buy a bag to try make the same cup at home with the wilfa, its a different world. Missing so much of the fruity notes. So with a short brew ratio my experience is that it absolutely make a noticible difference, but what if the brew time expands like cold brew or even french press?

Maggiekw wrote: ... but what if the brew time expands like cold brew or even french press?

Yes, since its a function of the fines % since they extract faster than the targeted grind size. I've noticed it more with pourovers and Areopresses

Long ,short, it doesn't matter.

Grinder makes a fair difference in the taste of coffee, because the particle size distribution they produce is all different

a grinder that produces a more uniform grind will have greater clarity in the cup regardless of brew method whereas a grinder which has a greater amount of fines may be described as having more body but with less clarity and more muddied. This is because grinds of different sizes extract at different rates. but it is true with immersion this is less noticeable, the extraction process with immersion is through infusion where there is a gradient concentration in the bed of coffee that eventually will equalize so that there is no difference between the top of the immersion brewer than with the bottom. With immersion over enough time I suppose theoretically all the coffee that can extract will extract regardless of grind size. In practice, however, with normal brew times for 4-5 min the extraction is based on how well the infusion process can perform in that time so if there is a very large difference of grind size you would probably notice the difference. I don't press my french presses after 4-5 min I break the crust by stirring the surface and all the coffee sinks, I then wait for another 5 min to give time for all the coffee to sink which makes for a cleaner brew, the infusion process will still be happening during this time just at a slower rate. However with cold brew since the brew is left for so long the infusion process has lots of time to extract and probably doesn't matter much provided you wait long enough. if you do have too many fines and you don't filter it well there will be a a greater amount of suspended solids (all those fines) which will make for a more gritty mouth feel.

DamianWarS wrote:With immersion over enough time I suppose theoretically all the coffee that can extract will extract regardless of grind size.

Particle size matters even when brewed long enough to achieve equilibrium TDS. Temperature has a smaller effect. So it stands to reason that the particle distribution of a grinder will have a measurable effect on extraction. But whether or not you can taste it -- which is the OP's question -- is harder to answer without, you know, trying it.



An equilibrium desorption model for the strength and extraction yield of full immersion brewed coffee, Scientific Reports, 2021

Maggiekw wrote:So with a short brew ratio my experience is that it absolutely make a noticible difference, but what if the brew time expands like cold brew or even french press?

It's a very good question. I know from my own tasting that in the Clever dripper (5 minute immersion brew time, like a French Press, but with a paper filter), grinders that are designed for brew (Bunn, Vario/Forte with brew burrs, & Fuji with ghost burrs) do noticeably better than those with espresso burrs (Vario/Forte with ceramic burrs, and commercial conical grinders)

One theory is that high extraction yields are the royal road to better coffee. But in many taste tests, very high extraction yields are not necessarily correlated with better or clearer tasting coffee; and that coffees with identical EYs can taste quite different. The other standard theory is that narrower particle distributions produce clearer cups. This I think has merit for brewing, where 1) there are big differences between burr sets, and 2) particle distributions are easy to measure (laser measurements become less accurate in the espresso range; and particle distributions are harder to characterize when fines and coarse distributions strongly overlap).

So my guess is that the difference will hold up.

Interesting to hear all your thoughts. I will make two cold brews right now. One with the cheap wilfa aroma with conical burrs, and one with the lagom p100 with HU burrs. I will report the results in two days time.

If you have anyone around see if you can cup them blind and add a 50:50 mix in there as well.