1:3 — Ratios, papers, pressure and pours
Edition No. 23
1 Fun Thing
A compressor is an audio engineering tool used to reduce the volume/level of an audio track if it exceeds a certain threshold. This helps control the dynamics by lowering the loudest parts, and giving the track a more even volume throughout. The amount of reduction is determined by a ratio, typically 2:1, 4:1 or 8:1. The higher the ratio the more aggressive the reduction.
3 Coffee Facts
Not all paper filters are made equal — the material, thickness and internal fibre structure all determine how porous it is and thereby affect the flow of water through it. Companies like Cafec make different filters for different roast levels… so experiment, and find one that works well for you.
If you graph the pressure applied to the puck over the course of brewing a shot of espresso you will arrive at a pressure profile for that pull. Traditional espresso is brewed at a flat 9 bars throughout the shot. Modern espresso uses a gentle ramp down on pressure as the shot progresses to help maintain puck integrity and reduce channeling. There are several such profiles and each affect the taste of the espresso in different ways.
The height from which you pour water onto a bed of coffee determines how much it agitates the grounds and increases extraction. According to research by Jonathan Gagné, pouring from a height where the steam of water from the kettle just starts to break up as it touches the slurry, will give you maximum agitation.