Serving People Serving Coffee Since 2005
Issue link: http://baristamagazine.epubxp.com/i/804825
The fl ow rate of water is different across my groups. This will obviously change my extractions, so how can I maintain consistency? This is a service call we get all the time at Black Rabbit. The fi rst thing we should cover is how to do a proper fl ow rate test. I always carry a small measuring cup in my tool bag that is marked in milliliters. Drop the dispersion screw, screen, and block on all the group heads. (Be careful here. Some machines don't shoot the water straight down. It may come out at an angle. If this is the case with your machine, leave the screen and block in.) Place your measuring cup under the fi rst group head, then hit the brew switch and start a timer simultaneously. I usually turn the group off and stop the timer when the water reaches 200 ml. Take note of what the time is and do the same thing on the next group head over. We usually run that test 4-5 times on each group head, hoping each group will hit that 200 ml line with no more than a half a second or so differ- ence between them. We typically like to recommend a "front-end rebuild" at least once every two years, which meansv replacing all the valve plungers and fl ow restrictors (a.k.a. gicleurs or group jets), and replacing the impellers on the fl ow meters if your machine has them. Sometimes we'll also replace the banjo tubes or adaptors if the machine has them. Of course, good cleaning habits and replacing your dispersion screens and fi lter baskets regularly help a lot, too! —Double J My grinder is producing coffee that is wildly incon- sistent in terms of particle size. What can I do to help fi x this? I fi gure I'll tackle another grinder question since we get a lot of them, and grinders are fun, mysterious, and often the unsung hero/workhorse in the café! Particle distribution, as the kids call it, is something that is hotly debated among coffee pros, from baristas to technicians to grinder manufacturers. Everyone has an opinion on what's right and wrong. One thing almost everyone can agree on, however, is this: If it is "wildly inconsistent," then something is defi nitely wrong. Depending on the type of grinder and the brew method you're going for, some inconsistent particle size can be benefi cial as you extract different particle sizes at different rates and you can actually miss out on some good fl avor or aromatic compounds in there if every single particle is identical in size and shape. When we're talking espresso, though, any inconsistency in particle size would be tough to distinguish with the naked eye, so if you see massively different particle sizes in an espresso grind, you can bet If your grinder burrs are not perfectly parallel with each other, you'll definitely get a noticeably inconsistent grind. 109 www.baristamagazine.com