Physicists Study How To Best Brew Coffee With Fewer Grounds – CoffeeTalk

Researchers at the University of Pennsylvania have discovered a way to maximize flavor with fewer coffee grounds. The cost of raw arabica beans, the core component of most coffee, has spiked in recent years due to four consecutive seasons of adverse weather. Climate change has added further strain, threatening the delicate temperature balance required by the Coffea arabica plant. This growing pressure has inspired physicists at the University of Pennsylvania to ask: Can we make great coffee with fewer beans?

The findings, published in the journal Physics of Fluids, provide a scientific approach to improving extraction efficiency so fewer coffee grounds can go further without diminishing overall quality. The team used a gooseneck kettle, coffee grinder, and a pour-over setup alongside precise measurements and high-speed analysis to study the fluid dynamics and mechanics of coffee brewing to uncover ways to maximize flavor with fewer grounds.

The experiment required making the invisible visible, so co-author Ernest Park, a graduate researcher in the Mathijssen Lab, explained that coffee’s opacity makes it tricky to observe pour-over dynamics directly. They swapped in transparent silica gel particles in a glass cone, and a laser sheet and high-speed camera allowed them to watch water streams create “miniature avalanches” of particles, revealing the flow’s inner workings. Water poured from a height produces the avalanche effect that stirs the bed of particles and enhances extraction.

A key factor in this process is laminar, or smooth and nonturbulent flow—made possible by a gooseneck kettle, even with a gentle pour-over flow. The team discovered that when water is poured from a height, it creates a stronger mixing effect. When brewing a cup, what gets all of that coffee taste and all of the good stuff from the grounds is contact between the grounds and the water.

If poured from too great a height, the water stream breaks apart into droplets, carrying air with it into the coffee cone, which can actually decrease extraction efficiency. The researchers conducted additional experiments with real coffee grounds to measure the extraction yield of total dissolved solids. Their results confirmed that the extraction of coffee can be tuned by prolonging the mixing time with slower but more effective pours that utilize avalanche dynamics.

The study is a love letter to coffee and a window into the team’s broader research. It helps understand how water erodes rock under waterfalls or behind dams, as well as wastewater treatment and filtration systems. The project also reflects ongoing research in the lab, as Park is working on microscale active surfaces that use rotating magnetic fields to clean biofilms from medical devices.

Read More @ phys.org