Wort is continuously supplied to a circuit including an elongated closed channel and through which micro-organisms are fed. After fermentation has taken place in the circuit, the mixture of wort and micro-organisms is centrifuged to separate it into fermented wort, a living cell mass and impurities, these three components being separately discharged from the centrifuge. The separate discharges of fermented wort and living cell mass are continuous, and the latter discharge includes an excess of living cells formed in the circuit, an amount of cell mass corresponding to this excess being discharged from the circuit.