Alcoholic Fermentation without Yeast Cells*

Until now it has not been possible to separate fermenting activity from living yeast cells; the following describes a procedure that solves this problem. One thousand grams of brewer’s yeast1 that had been cleaned as a prerequisite for the preparation of compressed yeast, but to which no potato starch had been added, is carefully mixed with the same weight of quartz sand2 and 250 g Kieselguhr. It is then triturated until the mass has become moist and pliable. Now 100 g of water are added to the paste, it is wrapped in filter cloth and gradually subjected to a pressure of 400–500 atmospheres: 350 cc press juice are obtained. The residual cake is again triturated, sieved, and 100 g water are added. A further 150 cc of press juice result when the cake is again subjected to the same pressure in the hydraulic press. One kg of yeast hence yields 500 cc press juice, containing about 300 cc cell substances. Traces of turbidity are now removed by shaking the press juice with 4 g of Kieselguhr and filtering through paper with repeated refiltration of the first portions. The resulting press juice is a clear, slightly opalescent yellow liquid with a pleasant yeast odour. A single determination of the specific gravity gave a value of 1.0416 (17°C). A large amount of coagulum separates upon boiling, so that the liquid almost completely