A recent experiment showed that, contrary to theoretical predictions, beyond a cutoff point, grinding coffee more finely results in lower extraction. One potential explanation for this is that fine grinding promotes non-uniform extraction in the coffee bed. We investigate the possibility that this could occur due the interaction between dissolution and flow promoting uneven extraction. A low dimensional model in which there are two possible pathways for flow is derived and analyzed. This model shows that, below a critical grind size, there is a decreasing extraction with decreasing grind size as is seen experimentally. This is due to a complicated interplay between an initial imbalance in the porosities and permeabilities of the two pathways in the model, which is increased by flow and extraction, leading to the complete extraction of all soluble coffee from one pathway.
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Uneven extraction in coffee brewing
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Research Article|
May 09 2023
Uneven extraction in coffee brewing
Special Collection:
Special Issue on Food Physics
W. T. Lee
;
W. T. Lee
a)
(Investigation, Methodology, Writing – original draft, Writing – review & editing)
School of Computing and Engineering, University of Huddersfield
, Queensgate, Huddersfield HD1 3DH, United Kingdom
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A. Smith
;
A. Smith
b)
(Investigation, Methodology, Writing – original draft, Writing – review & editing)
School of Computing and Engineering, University of Huddersfield
, Queensgate, Huddersfield HD1 3DH, United Kingdom
b)Author to whom correspondence should be addressed: a.smith@hud.ac.uk
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A. Arshad
A. Arshad
(Investigation, Software)
School of Computing and Engineering, University of Huddersfield
, Queensgate, Huddersfield HD1 3DH, United Kingdom
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b)Author to whom correspondence should be addressed: a.smith@hud.ac.uk
a)
Also at: MACSI, University of Limerick, Limerick, Ireland.
Note: This paper is part of the special topic, Special Issue on Food Physics.
Physics of Fluids 35, 054110 (2023)
Article history
Received:
December 16 2022
Accepted:
March 24 2023
Citation
W. T. Lee, A. Smith, A. Arshad; Uneven extraction in coffee brewing. Physics of Fluids 1 May 2023; 35 (5): 054110. https://doi.org/10.1063/5.0138998
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