Method for Purification of Lactose

Abstract

The present invention relates to improved methods of purification of sugars and in particular to a method of preparing lactose. A low purity lactose source such as whey is subjected to a first demineralization step involving either ion-exchange or the addition of divalent metal cations, followed by a second demineralization step where alcohol is added. The invention also relates to lactose produced by this method and products comprising lactose produced by this method.

1 . A method of preparing high-purity lactose in the form of rosette-shaped crystals from a lower purity lactose source including the steps as follows:
 (a) primary demineralisation of the lactose source by treatment with about 0.014M to 0.025M divalent metal ions to provide a lactose-containing solution and a mineral precipitate, and   (b) secondary demineralisation of the lactose-containing solution from step (a) by addition of alcohol at a concentration of about 25% to 75% total liquid volume to provide a lactose containing-solution and a mineral precipitate, and   (c) crystallisation of the lactose-containing solution from step (b).   
     
     
         2 . (canceled) 
     
     
         3 . A method according to  claim 1  wherein the crystallisation is carried out by a single step procedure. 
     
     
         4 . A method according to  claim 1  wherein the crystallisation is carried out over a period of about 4 hours. 
     
     
         5 . A method according to  claim 1  wherein the crystallisation is carried out over a period of about 2 hours. 
     
     
         6 . (canceled) 
     
     
         7 . A method according to  claim 1  wherein the primary demineralisation step is achieved by passage of the lower purity lactose source through a cation exchange resin and/or an anion exchange resin. 
     
     
         8 . A method according to  claim 1  wherein the lactose-containing solution from step (a) is concentrated to 20% to 60% total solids before step (b). 
     
     
         9 . A method according to  claim 1  wherein the divalent metal ion is calcium, magnesium or barium. 
     
     
         10 . A method according to  claim 1  wherein the divalent metal ion is calcium derived from calcium chloride or calcium hydroxide; magnesium derived from magnesium chloride; or barium derived from barium chloride. 
     
     
         11 . (canceled) 
     
     
         12 . A method according to  claim 1  wherein the alcohol is ethanol, methanol, isopropanol or propanol. 
     
     
         13 . A method according to  claim 12  wherein the alcohol is ethanol. 
     
     
         14 . (canceled) 
     
     
         15 . A method according to  claim 13  wherein the ethanol is present at approximately 60% total liquid volume. 
     
     
         16 . A method according to  claim 1  wherein the temperature of the divalent metal ion-treated solution and the alcohol is between 40° C. and 79° C. 
     
     
         17 . A method according to  claim 1  wherein the temperature of the divalent metal ion-treated solution and the alcohol is about 78° C. 
     
     
         18 . A method according to  claim 1  wherein the step (c) is carried out in alcohol. 
     
     
         19 . A method according to  claim 1  herein the step (c) is carried out in alcohol present at between 25% to 75% total liquid volume. 
     
     
         20 . A method according to  claim 1  wherein the crystals formed in step (c) are washed with an alcoholic solution containing between 0% and 20% water. 
     
     
         21 . A method according to  claim 1  wherein the high purity lactose has less than 0.3% ash. 
     
     
         22 . A method according to  claim 1  wherein the high purity lactose is pharmaceutical grade lactose with less than 0.1% ash. 
     
     
         23 . A method according to  claim 1  wherein, when clarified whey screened to remove cheese particles and centrifuged to remove fat is used as the lower purity lactose source, the divalent metal ion treatment of step (a) is preceded by an ultrafiltration step to obtain whey permeate. 
     
     
         24 . A method according to  claim 1  wherein the lactose-containing solution from step (a) is treated with one or more absorbents. 
     
     
         25 . A method according to  claim 24  wherein the absorbent is charcoal. 
     
     
         26 . A method according to  claim 24  wherein the lactose-containing solution from step (a) treated with one or more absorbents is concentrated by nanofiltration and evaporation prior to step (b). 
     
     
         27 . A method according to  claim 1 , wherein the high purity lactose is recovered by centrifugation and is further washed and dried. 
     
     
         28 - 30 . (canceled) 
     
     
         31 . Lactose in the form of rosette-shaped crystals produced by a method according to  claim 1 . 
     
     
         32 . Lactose according to  claim 31  wherein the lactose is of food grade standard. 
     
     
         33 . Lactose according to  claim 31  wherein the lactose is of pharmaceutical grade standard. 
     
     
         34 . Lactose according to  claim 31  wherein the lactose has a bulk density of 0.40 to 0.70 g/ml. 
     
     
         35 . Lactose in the form of rosette-shaped crystals. 
     
     
         36 - 50 . (canceled)