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Exploring the link between coffee matrix microstructure and flow properties using combined X-ray microtomography and smoothed particle hydrodynamics simulations
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Luciano Navarini,
Furio Suggi Liverani,
Marco Ellero
Scientific Reports, Volume: 13, Issue: 1
Swansea University Authors:
Richard Johnston , Marco Ellero
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DOI (Published version): 10.1038/s41598-023-42380-y
Abstract
Coffee extraction involves many complex physical and transport processes extremely difficult to model. Among the many factors that will affect the final quality of coffee, the microstructure of the coffee matrix is one of the most critical ones. In this article, we use X-ray micro-computed (microCT)...
| Published in: | Scientific Reports |
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| ISSN: | 2045-2322 |
| Published: |
Springer Science and Business Media LLC
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa64681 |
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| Abstract: |
Coffee extraction involves many complex physical and transport processes extremely difficult to model. Among the many factors that will affect the final quality of coffee, the microstructure of the coffee matrix is one of the most critical ones. In this article, we use X-ray micro-computed (microCT) technique to capture the microscopic details of coffee matrices at particle-level and perform fluid dynamics simulation based on the smoothed particle hydrodynamics method (SPH) with the 3D reconstructured data. Information like flow permeability and tortuosity of the matrices can be therefore obtained from our simulation. We found that inertial effects can be quite significant at the normal pressure gradient conditions typical for espresso brewing, and can provide an explanation for the inconsistency of permeability measurements seen in the literature. Several types of coffee powder are further examined, revealing their distinct microscopic details and resulting flow features. By comparing the microCT images of pre- and post-extraction coffee matrices, it is found that a decreasing porosity profile (from the bottom-outlet to the top-inlet) always develops after extraction. This counterintuitive phenomenon can be explained using a pressure-dependent erosion model proposed in our prior work. Our results reveal not only some important hydrodynamic mechanisms of coffee extraction, but also show that microCT scan can provide useful microscopic details for coffee extraction modelling. MicroCT scan establishes the basis for a data-driven numerical framework to explore the link between coffee powder microstructure and extraction dynamics, which is the prerequisite to study the time evolution of both volatile and non-volatile organic compounds and then the flavour profile of coffee brews. |
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| Keywords: |
Coffee extraction, coffee matrix microstructure, X-ray microtomography, smoothed particle hydrodynamics |
| College: |
Faculty of Science and Engineering |
| Funders: |
This research is supported by the illycaffè S.p.A. through the project “Modelling and simulating espresso coffee extraction at the mesoscopic scales”. Financial support from the BERC 2022-2025 program and by the Spanish State Research Agency through BCAM Severo Ochoa Excellence Accreditation CEX2021-001142-S/MICIN/AEI/10.13039/501100011033 and through the project PID2020-117080RB-C55 (“Microscopic foundations of soft matter experiments: computational nano-hydrodynamics” - acronym “Compu-Nano-Hydro”) are also acknowledged. The microCT work was supported by the Advanced Imaging Materials (AIM) core facility (EPSCR Grant No. EP/M028267/1), and the European Social Fund (ESF) through the European Union Convergence programme administered by the Welsh Government (80708). |
| Issue: |
1 |