A process for producing dairy products with a defined lactose content is suggested, comprising the following steps:(a) Ultrafiltration of a starting milk for producing a first permeate P1 and a first retentate R1 (b) Nanofiltration of the first permeate P1 for producing a second perorate P2 and a second retentate R2 (c) Hydrolysis of the second retentate R2 while adding lactase(d) Mixing the first retentate R1 with such an amount of the second permeate P2 and the hydrolysis product of step (c) each that a standardized dairy product is obtained, the content of proteins and minerals of which corresponds to the one of the starting milk.
