A major focus in updated brewing science is the importance of .
The brewing process begins with the physical properties of the coffee grounds. Crushing roasted beans into small particles creates the physical framework for extraction. Surface Area Multiplication
The Physics of Filter Coffee: Understanding the Science Behind the Brew the physics of filter coffee epub updated
Fines migration causes clogging, while boulders lead to uneven extraction.
The original book became an instant hit in 2020 because it answered the "why" behind the "how." Why does a faster pour lead to astringency? Why do flat-bottom brewers (like the Kalita Wave) extract more evenly than cone-shaped brewers (like the V60)? Gagné provides the equations. A major focus in updated brewing science is
Water temperature directly affects the kinetic energy of the molecules. Higher temperatures (typically 90°C to 96°C) increase the molecular motion. This speeds up the diffusion rate and allows water to break down heavier, less soluble organic compounds. 2. Hydrodynamics and Fluid Flow Through Porous Media
Where $C$ = concentration in water, $C_s$ = saturation concentration at particle surface, $A$ = surface area, $k_m$ = mass transfer coefficient. Surface Area Multiplication The Physics of Filter Coffee:
The coffee bed behaves like a . Water flow is dictated by the density of the bed and its thickness . A deeper bed (typical in Chemex) creates more resistance to flow than a shallow bed [1]. Channeling and Flow Dynamics
A standard coffee bed retains roughly twice its weight in water. This retained liquid holds a proportional amount of dissolved coffee solids, which is why optimizing your yield requires balancing your starting water-to-coffee ratio carefully. Summary of Key Variables Physical Variable Impact on Brew How to Control It Governs surface area and flow resistance Use high-quality burr grinders Water Temperature Controls kinetic energy and solubility rates Preheat gear; use a temperature-controlled kettle Hydrostatic Pressure Alters flow velocity through the coffee bed Control pour height and water volume in the cone Agitation (Turbulence) Breaks up boundary layers; speeds up diffusion Stir gently or use a controlled pouring pattern
Gagné analyzes the impact of water flow on the slurry, applying surprising studies on to help understand turbulence. He also introduces the concept of brewer geometry and bypass , comparing how different drippers (V60, Kalita, etc.) physically alter the extraction.
