Espresso coffee is made by forcing hot water under high pressure through a compacted bed of finely ground coffee. (b) Drip filter brewing involves pouring hot water over a loose bed of coarser coffee in a filter. In either method, water flows through the bed, leaching soluble coffee components from the grains. Any undissolved solids in the fluid are filtered from the extract as the liquid leaves the filter. (Image courtesy of Kevin M. Moroney.)
Transfers included in the coffee extraction model (reproduced from Moroney et al, “Modelling of coffee extraction during brewing using multiscale methods: An experimentally validated model,” The diagram shows the transfers of water and coffee which are described by the coffee extraction model presented in the published research. (Image courtesy of Kevin M. Moroney.)
That’s why the new research focuses on simplified equations to capture the essence of the process, while still considering brew ratio, brewing time, water quality and temperature, grind size and distribution, and extraction uniformity.
Location of coffee in the bed: The coffee bed consists of (intergranular) pores and grains. (Image courtesy of Kevin M. Moroney.)
The authors recently published their findings in the SIAM Journal on Applied Mathematics, with the goal of inspiring further research on extraction processes, and aiding coffee lovers the world over in their quest for the perfect cup.