Coffee starts losing quality almost immediately upon grinding. The best-tasting brews are made from beans ground just before brewing. Coffee connoisseurs prefer to grind in burr mills (e.g., Solis, Zassenhaus, Rancilio). The cheap electric "whirly blade" grinder don't grind the particles consistently meaning you end up with lots of small fines and large coarse grounds in the same pile. The resultant coffee, regardless of the brew method used will be both over and over extracted leading to combinations of bitter and sour notes in the coffee.
anonymousMaking-Coffee August 02, 2018 at 8:20 am