Preparation of cellobiuronic acid from polysaccharide

Abstract

Cellobiuronic acid may be prepared by hydrolysis of gellan. The method provides embodiments expressed in terms of amounts of cellobiuronic acid produced, amounts of gellan gum hydrolyzed and amounts of cellobiuronic acid present in fractions of a hydrolysate The method may further include isolation of a separated fraction of the hydrolysate where the separated fraction comprises cellobiuronic acid. A preferred embodiment of the method includes hydrolyzing gellan gum with a protic acid under reaction conditions that convert at least 95 wt.% of the gellan gum to a hydrolysate comprised of cellobiuronic acid and monosaccharides and isolating a separated fraction of the hydrolysate where cellobiuronic acid comprises at least a 95 wt.% of saccharides in the separated fraction.

What is claimed is:  
     
         1 . A method of preparing cellobiuronic acid comprising: 
 exposing polysaccharide to partially hydrolyzing conditions to produce a hydrolysate comprising saccharides, the saccharides comprising cellobiuronic acid; and    isolating the cellobiuronic acid; wherein,    the polysaccharide comprises oxidized and nonoxidized monosaccharide residues where oxidized monosaccharide residues are not directly bonded together, and the oxidized monosaccharide residues comprise at least 10% of the total number of residues.    
     
     
         2 . The method of    claim 1    wherein the polysaccharide has not previously been subjected to a synthetic oxidation process.  
     
     
         3 . The method of    claim 1    wherein the polysaccharide comprises residues of glucuronic acid and other monosaccharides selected from the group consisting of fructose, galactose, mannose and rhamanose.  
     
     
         4 . The method of    claim 1    wherein the oxidized monosaccharide residues comprise at least 40% of the total of the residues.  
     
     
         5 . The method of    claim 1    wherein the oxidized monosaccharide residue comprises a carboxylic acid group.  
     
     
         6 . The method of    claim 1    wherein the oxidized monosaccharide comprises a carboxylic ester group.  
     
     
         7 . The method of    claim 1    wherein the polysaccharide is gellan.  
     
     
         8 . The method of    claim 7    wherein the gellan is clarified gellan.  
     
     
         9 . The method of    claim 7    wherein the gellan is deacetylated gellan.  
     
     
         10 . The method of    claim 1    wherein acid hydrolysis is used to produce the hydrolysate.  
     
     
         11 . The method of    claim 1    wherein the hydrolysate comprises about 30 to about 60 wt. % disaccharide based on the total weight of saccharides in the hydrolysate.  
     
     
         12 . The method of    claim 1    wherein the hydrolysate comprises about 40 to about 50 wt. % cellobiuronic acid based on the total weight of saccharide in the hydrolysate.  
     
     
         13 . The method of    claim 1    wherein the hydrolysate comprises at least 70 wt. % monosaccharide and disaccharide, based on the total weight of saccharide in the hydrolysate.  
     
     
         14 . The method of    claim 1    wherein the hydrolysate comprises at least 60 wt. % of monosaccharide and disaccharide, based on the total weight of polysaccharide.  
     
     
         15 . The method of    claim 1    wherein the hydrolyzing produces a hydrolysate comprising at least 100 grams of cellobiuronic acid.  
     
     
         16 . The method of    claim 1    wherein the hydrolyzing produces a hydrolysate comprising at least 1,000 grams of cellobiuronic acid.  
     
     
         17 . The method of    claim 1    wherein the isolation provides a separation of disaccharide from both monosaccharide and oligosaccharide.  
     
     
         18 . The method of    claim 1    wherein the isolation comprises anion exchange chromatography.  
     
     
         19 . The method of    claim 1    wherein the isolation comprises precipitation.  
     
     
         20 . The method of    claim 1    wherein the isolated cellobiuronic acid is essentially free from glucose.  
     
     
         21 . The method of    claim 1    wherein at least 100 grams are isolated.  
     
     
         22 . A method of hydrolyzing polysaccharide comprising contacting polysaccharide with a hydrolyzing agent selected from the group consisting of acid, base and hydrolytic enzyme, under conditions that provide a hydrolysate comprising disaccharide and monosaccharide, wherein the disaccharide comprises cellobiuronic acid, and the cellobiuronic acid is present in the hydrolysate at a concentration of at least 5 wt. % based on the total weight of polysaccharide, and wherein the polysaccharide has not previously been subjected to oxidizing conditions.  
     
     
         23 . The method of    claim 22    wherein the polysaccharide is gellan.  
     
     
         24 . The method of    claim 23    wherein the gellan is selected from the group consisting of native gellan gum, clarified gellan gum, deacetylated gellan gum and gellan gum that is both clarified and deacetylated.  
     
     
         25 . The method of    claim 22    wherein the hydrolysate comprises at least 20 wt. % cellobiuronic acid based on the total weight of polysaccharide.  
     
     
         26 . The method of    claim 22    wherein the hydrolysate comprises at least 100 grams of cellobiuronic acid.  
     
     
         27 . The method of    claim 22   , further comprising separating cellobiuronic acid from monosaccharide.  
     
     
         28 . The method of    claim 22   , further comprising isolating an anionic fraction comprising cellobiuronic acid from a neutral fraction comprising one or more monosaccharides.  
     
     
         29 . The method of    claim 22   , further comprising separating monosaccharide and disaccharide from other saccharide species present in the hydrolysate.  
     
     
         30 . The method of    claim 22   , further comprising separating monosaccharide from disaccharide, wherein the disaccharide comprises cellobiuronic acid.  
     
     
         31 . The method of    claim 22   , further comprising isolating cellobiuronic acid in a solvent-free form.  
     
     
         32 . A method of hydrolyzing gellan comprising contacting gellan with an aqueous composition having a pH between 2 and 7, under conditions effective to partially hydrolyze the gellan to cellobiuronic acid, and separating the cellobiuronic acid from water.