A method for preparing a liquid comestible from a cell by passing liquid through the substance using centrifugal forces, wherein gas contained in the cell is controllably purged from the cell as liquid fills the cell. In one embodiment, the method includes prewetting the substance in the cell by filling liquid in the cell and rotating the cell at a first rotational speed; and then extracting the liquid comestible from the cell in an extraction phase which comprises continuing to fill liquid into the cell and rotating the cell at a second rotational speed that is higher than the first rotational speed. The invention also discloses a cell for use in these methods which cell includes a filter for preventing solids from being carried by gas during the gas purge.