transit in the coffee bed is noxious for the quality of the extract because, under these conditions, such fluids are more efficient in solubilizing less soluble compounds, generally conferring bitterness and astringency [12], and/or in stripping least volatile aroma compounds which are organoleptically unpleasant and described as clove-like, smoky, burnt, medicinal/chemical [13]. This is witnessed by an extraction yield (defined as the percentage of the brew total solids with respect to ground and roasted coffee dose) which is generally higher in comparison with the other brewing methods (e.g. filter, espresso, plunger or ‘‘French Press”). In particular extraction yield ranging from 18% to