X-ray tomography offers detailed look at early stage of espresso brewing
X-ray tomography offers detailed look at early stage of espresso brewing lead image
Coffee is one of the world’s most popular beverages, and there are as many ideas about how to brew the perfect cup as there are people who drink it. One of the most common types of coffee consumption is espresso, brewed by forcing high temperature, high pressure water through pressed coffee grounds.
Although research on espresso brewing typically treats the bed as fully saturated by water throughout the brewing process, a significant part of that process is comprised of the infiltration stage, where water slowly permeates the bed of espresso grounds.
Foster et al. employed X-ray tomography to study this infiltration process and used that data to inform a flow model. Employing this more accurate model could lead to better-tasting coffee.
“Understanding the infiltration process gives insights into the extraction rate across the coffee bed,” said author Ann Smith. “Over-extracting coffee results in bitter taste whilst under-extraction leads to both weak brews and wasted resources.”
The authors employed a rotating X-ray system (ROXS) to build a 3D reconstruction of the coffee machine. The high rotation speed of the system allowed them to achieve both high spatial and temporal resolution while keeping the coffee machine stationary. They then fed this X-ray data into a one-dimensional unsaturated porous medium flow model, which demonstrated agreement with the experimental results.
The team plans to further improve their model by examining the effects of brewing temperature and studying the transport of soluble material during the infiltration process.
“Incorporating measurements of the mass concentration of coffee exiting the coffee bed should provide a richer model validation dataset,” said Smith.
Source: “Dynamics of liquid infiltration into an espresso bed using time-resolved micro-computed tomography: Insights from experiment and modelling,” by Jamie Michael Foster, William Lee, Kevin Moroney, Dimitri Prjamkov, Michael Salamon, Ann Smith, Joseph Petrassem-de-Sousa, and Michael Vynnycky, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0245167 .
This paper is part of the Kitchen Flows 2024 Collection, learn more here .
