Sugar beet membrane filtration process

The present invention relates to a process for producing sugar from beets, comprising the steps of: (f) macerating sugar beets or pieces thereof, thereby producing a macerated material that comprises pulp and liquid, (g) separating the liquid in the macerated material from the pulp at a temperature of at least about 65 C to produce a sucrose-containing feed juice; (h) filtering the sucrose-containing feed juice through a first ultrafiltration membrane that has a first molecular weight cutoff, thereby producing a first ultrafiltration permeate and a first ultrafiltration retentate; (i) filtering the first ultrafiltration permeate through a second ultrafiltration membrane that has a second molecular weight cutoff that is lower than the first molecular weight cutoff, thereby producing a second ultrafiltration permeate and a second ultrafiltration retentate; and filtering the second ultrafiltration permeate through a nanofiltration membrane, thereby producing a nanofiltration permeate and a nanofiltration retentate, wherein the nanofiltration retentate has a higher concentration of sucrose on a dry solids basis than the feed juice in step (c).