%0 Journal Article
%9 Article
%W National Agricultural Library
%~ PubAg
%B Journal of food engineering
%T A new methodology to estimate the steady-state permeability of roast and ground coffee in packed beds
%A Corrochano, B.R.
%A Melrose, J.R.
%A Bentley, A.C.
%A Fryer, P.J.
%A Bakalis, S.
%V 2015 v.150
%K brewing
%K equations
%K mass transfer
%K methodology
%K particle size distribution
%K permeability
%K porosity
%M 5415224
%X In an espresso-style extraction hot water (90±5°C) is driven through a coffee packed bed by a pressure gradient to extract soluble material from the coffee matrix. Permeability is a key parameter affecting extraction as it determines the flow rate through the bed and hence brewing and residence time. This may alter bed-to-cup mass transfer and therefore impact brew quality.In this work a methodology that will allow estimation of the permeability of coffee packed beds in steady-state was developed. Fitting measured flow rate – pressure drop data to Darcy’s law resulted in permeability values in the range of 10−13–10−14m2. Disagreement between the experimental and theoretical permeability, as estimated from dry measurements of particle size distribution and Kozeny–Carman equation, was found. Bed consolidation may have a larger effect on the packing structure than the mere decrease in bed bulk porosity. The Kozeny–Carman equation, corrected with a porosity-dependent tortuosity according to a power law, gave a good fit of the data.
%D 2015
%= 2019-09-30
%G
%8 2015-04
%V v. 150
%P pp. 106-116
%R 10.1016/j.jfoodeng.2014.11.006