I think there has to be a difference. When developing the AeroPress, I conducted blind taste testing on about 15 people ranging from full time coffee professionals to coffee lovers. All but one chose 175F brewings.
The sole exception chose 165F. He is a serious espresso drinker with a $600 Italian grinder and a $1,500 espresso machine. He spends a couple of months every spring in Italy and drinks cafe espresso every day there. At home in California he strives to duplicate the cafe espresso in his own kitchen.
I too prefer a medium roast, with my strike sweet spot between 193-198 °F.
I am still experimenting with the following:
-Grind coarseness (though I have been leaning towards the finer side of the scale) -steep time -agitation (both method and time... I have an affinity to glass stirring rods, as opposed to the paddle) -steep vessel (Netphilosophers MJ method has piqued my curiosity...especially when look for larger volume brews).
This obviously has resulted in a broad spectrum of tasting notes... once dialed into a profile that hits my palate perfect, I will start honing in on the maths.
Maybe it would be useful to include a definition key for these terms or a link to such a key, at least for those 0.02% who care? You don't even specify units.
Does L mean you lost 6% of your brew mass??
-Lower temperatures tend to be smoother, with a muting or elimination of fruit notes and a loss of brightness. Especially apparent on citrusy coffees (like Tanzania, or Kenya), fruity coffees (Ethiopia, Uganda), and floral-bright coffees (Guatemala, other hi-elevation Centrals). Less apparent on nutty or cocoa noted coffees like Brazilian or India Giri/Mysore, or earthy coffees from SE Asia (Sumatra, Indonesia).
I've found that as the grounds undergo dissolution in a steep vessel, they tend to waterlog and sink. This is to say they start out less dense than the brew water, and as the particles become saturated they are denser than the coffee solution.
The smaller the grind, the quicker it takes for them to sink. I can set up a french press using a whirlyblade grinder, and watch as the larger particles remain on top while the grounds continually rain down in larger and larger particles during the steep time.
In these three brews, the brew coffee powder essentially rained to the bottom of the jar/AP pretty much immediately after they were in contact with the water. By ten seconds in the Mason Jar, the majority of the grounds were already settled to the bottom as the swirling was slowing after being stirred.
With 1.5mm sieved grounds particles, it might take 4 minutes for this to happen, or longer if they are floating in a bed of off-gassing foam and you don't agitate the liquid or stir the larger particles in (or force them in contact with the brew water like a typical french press recipe).
I used to think that this is the time where about 20% dissolution occurs, but now I'm thinking this is an indicator that the dissolution is approaching the equilibrium dissolution.
However minute, I wonder much how fluid dynamics, surface area (of the grinds) and frictional energies come into play when steeping and during agitation...as this could definitely affect the more volatile components of the brew process.
As an aside... I ran the following brew, and was pleasantly surprised... (hat tip to Netphilosopher for MJA method):
-28g medium roast Riolblanco, Columbian beans (roasted on sunday) -'0' setting on Baratza virtuoso... not quite "talc" per se, but definitely a nice fine, tight particulate. - 440g filtered water, 198°F kettle temp - 193°F strike temp
Placed grounds in 600ml pyrex beaker, poured over water and agitated with glass rod for 5 seconds.
Allowed for a 40 second steep, in which NP's observation was correct... within 15-20 seconds, it appeared that all grounds had settled to bottom of beaker and a rather active rolling bloom occurred.
Agitated once more with glass rod for 3 seconds
Pressed through an inverted aeropress, with rinsed paper microfilter (in 2 pressings) with firm pressure. The volume of the grinds and particulate size definitely added far more resistance than I have previously been used to.
Finished mass of 417g brewed coffee.
I did not measure post boil... so I am not quite sure how much liquid was lost to evaporation and what was left in compressed pucks.
The resultant brew had a wonderful, viscous mouth feel. Definite notes of cocoa, dark malt and hint of cherry..or tart fruits... as well as a nice earthiness (musty wood, but not sour). A nice hint of bitterness, but not so much so as to overpower everything else. Being a neophyte... and inexperienced taster at best, I really enjoyed the finished product.
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