Fluidized bed for coffee brewing

By Neil Thomas Stacey

coffee brewing engineering

Experimental and theoretical studies of the coffee brewing process have shown that most coffee preparation methods are affected by uneven particle distribution and uneven exposure of coffee grounds to hot water. This results in over-extraction from some percentage of the coffee granules and under-extraction from others, affecting both flavour and extraction efficiency.

Prior research has focused on adjusting parameters such as coarseness of grind, temperature and pressure of water, and duration of exposure to address these issues, but elementary chemical reactor design offers a more comprehensive solution: the fluidized bed, a type of chemical reactor where upward fluid flow through a particle bed generates enough of a pressure difference to suspend those particles, permitting them to move freely between one another.

All conventional coffee brewing methods are essentially packed-bed type extractors, and it is well-known in the chemical industry that fluidized beds offer superior fluid flow dispersion and homogeneity of particle distribution, hence providing more complete and more uniform contact solid-fluid contact. It follows that fluidized bed extraction methods would address the shortfalls of coffee brewing methods, resulting in more complete and more consistent extraction, improving flavour and strength while reducing the quantity of coffee grounds that must be used.

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