Abstract: A process for producing sugar from beets includes the step of filtering a sucrose-containing feed juice, which has been obtained from macerated sugar beets, through a first ultrafiltration membrane that has a first molecular weight cutoff. This ultrafiltration step produces a first ultrafiltration permeate and a first ultrafiltration retentate. The first ultrafiltration permeate is filtered through a second ultrafiltration membrane that has a second molecular weight cutoff that is lower than the first molecular weight cutoff. This second ultrafiltration step produces a second ultrafiltration permeate and a second ultrafiltration retentate. The second ultrafiltration permeate is nanofiltered through a nanofiltration membrane, thereby producing a nanofiltration permeate and a nanofiltration retentate.

Abstract: A nanofiltration process for obtaining sucrose uses a feed syrup, such as molasses, that comprises sucrose and no less than about 2% by weight invert sugars (on a dry solids basis). The nanofiltration produces a permeate and retentate. The nanofiltration permeate will comprise invert sugars that have passed from the feed through the nanofiltration membrane, and preferably will also comprise ash from the feed. The nanofiltration retentate has a higher concentration of sucrose and a lower concentration of invert sugars than the feed syrup. Sucrose can then be crystallized from the nanofiltration retentate. The reduction of the invert content in the syrup facilitates crystallization and thus enhances sucrose recovery.

Abstract: A process for producing sugar from beets includes the step of filtering a sucrose-containing feed juice, which has been obtained by diffusion from sliced sugar beets, through a first ultrafiltration membrane that has a first molecular weight cutoff. This ultrafiltration step produces a first ultrafiltration permeate and a first ultrafiltration retentate. The first ultrafiltration permeate is filtered through a second ultrafiltration membrane that has a second molecular weight cutoff that is lower than the first molecular weight cutoff. This second ultrafiltration step produces a second ultrafiltration permeate and a second ultrafiltration retentate. The second ultrafiltration permeate is nanofiltered through a nanofiltration membrane, thereby producing a nanofiltration permeate and a nanofiltration retentate.

Abstract: A process for producing sugar from cane includes the step of filtering a sucrose-containing feed juice, which has been obtained from macerated sugar cane, through a first ultrafiltration membrane that has a first molecular weight cutoff. This ultrafiltration step produces a first ultrafiltration permeate and a first ultrafiltration retentate. The first ultrafiltration permeate is filtered through a second ultrafiltration membrane that has a second molecular weight cutoff that is lower than the first molecular weight cutoff. This second ultrafiltration step produces a second ultrafiltration permeate and a second ultrafiltration retentate. The second ultrafiltration permeate is nanofiltered through a nanofiltration membrane, thereby producing a nanofiltration permeate and a nanofiltration retentate.

Abstract: The present invention relates to a process for producing sugar from cane that includes the steps of: (a) grinding sugar cane or pieces thereof into pulp; (b) mechanically separating juice from the pulp; and (c) membrane filtering the separated juice, for example through a ultrafiltration membrane, producing a retentate and a permeate. Preferably in step (a), the cane is cut into pieces having an average fiber length of less than 10 millimeters, more preferably into pieces having an average fiber length of less than 5 mm with a fiber diameter of about 200 microns or less. The mechanical separation of juice from cane pieces can be done suitably by filtration or centrifugation. It is preferred to adjust the pH of the separated juice to at least about 7 prior to membrane filtration, more preferably to at least about 7.5, for example by adding lime or sodium hydroxide. The permeate can be evaporated and crystallized by conventional means to produce white sugar.

Abstract: A nanofiltration process for obtaining sucrose uses a feed syrup, such as molasses, that comprises sucrose and no less than about 3% by weight invert sugars (on a dry solids basis). The nanofiltration produces a permeate and retentate. The nanofiltration permeate will comprise invert sugars that have passed from the feed through the nanofiltration membrane, and preferably will also comprise ash from the feed. The nanofiltration retentate has a higher concentration of sucrose and a lower concentration of invert sugars than the feed syrup. Sucrose can then be crystallized from the nanofiltration retentate. The reduction of the invert content in the syrup facilitates crystallization and thus enhances sucrose recovery.

Abstract: A process for purifying cane sugar from an aqueous composition thereof comprises the steps of (a) contacting an aqueous cane sugar feed composition with sufficient lime to increase the pH of the composition to at least about 9.5; (b) filtering the composition through a membrane having a pore size no greater than about 0.5 microns and having a molecular weight cutoff no less than about 5 kD, thereby producing a retentate and a permeate; and (c) contacting the permeate with sufficient carbon dioxide, or other materials designed to precipitate calcium and lower the pH, to adjust the pH to about 6.5-9.0. The feed composition preferably is cane juice, cane syrup, an aqueous composition of raw sugar, a cane sugar refinery stream, or a mixture of one or more such materials.