A process for producing lactose-free milk products is proposed in which(a) skimmed milk is subjected to an ultrafiltration or to a combination of dia- and ultrafiltration,(b) the lactose-free retentate R1 is fed to a storage container and the lactose-containing permeate P1 is fed to an enzyme reactor,(c) an amount of lactase sufficient for the enzymatic degradation of the lactose present therein is added to the permeate P1,(d) the reaction mixture obtained in this way is subjected to a nanofiltration,(e) the lactose-free permeate P2 is conveyed to the storage container and mixed with the lactose-free retentate R2, and(f) the retentate R2, which still comprises unreacted lactose and enzyme, is returned again to the enzyme reactor.
