A method of producing a processed kava product involves using an extraction solvent, such as liquid CO2, to preferentially extract different kavalactones from the source material at different rates. The tip portion of the shaft includes a locking step portion formed by providing an annular groove or a ring-shaped projection portion. Further, the power supply adjusting apparatus includes a secondary non-isolation adjusting and converting unit, adapted to convert the power supply signal outputted by the primary isolation converting unit to an expected voltage according to the adjustment control signal outputted by the voltage adjustment controlling unit and output the adjusted power supply signal.