| abstract |
A culture medium which is completely free of chemical additives and which can be used for the individual culture of yeast and of lactic acid bacteria or for the coculture of yeasts and lactic acid bacteria is prepared. The preparation of the medium is carried out by a process comprising making in a bioreactor a first medium using a dilute aqueous mixture containing a yeast autolysate and whole-meal or wheat germ, starch and gluten. Alpha-amylase enzymes and amyloglucosidase are added thereto for hydrolyzing the starch into a sugar. Furthermore proteolytic enzymes of food quality are also added for hydrolyzing gluten into aromatic peptides and free amino acids for microbial growth. The first medium is further sterilized and table salt may be added, however, no other chemical additives are ever added to the first medium. A second medium is prepared similarly as the first medium, however, in place of the second medium containing gluten it contains proteins for which the proteolytic enzymes of food quality are added for hydrolyzing the proteins into aromatic peptides and into free amino acids for microbial growth. The second medium is also further sterilized and table salt may be added, while no other chemical additives are added; and furthermore, the hydrolyses of the first and second mediums are carried out without pH regulation. The mediums are then combined to form a culture medium useful for making yeast cultures, lactic acid bacteria cultures and cocultures of yeast and lactic acid bacteria. |