Process for isomaltose production

Abstract

The present invention relates to a method of producing oligosaccharide syrups, in particular to the production of syrups having a high concentration of saccharides with a degree of polymerization of at least 2, comprising the steps of: enzymatic reaction of a substrate at a temperature in the range of 50° C. to 100° C. obtaining a saccharide solution comprising monosaccharides and disaccharides, trisaccharides and higher saccharides; nanofiltration of the saccharide solution at a temperature in the range of 60° C. to 100°C. obtaining a syrup essentially comprising disaccharides, trisaccharides and higher saccharides; recovering said syrup; optionally recycling the permeate resulting from the nanofiltration step to the enzymatic reaction.

1 . A method of producing an oligosaccharide syrup comprising the steps of: 
 enzymatic reaction of a substrate at a temperature in the range of 50° C. to 100° C. obtaining a saccharide solution comprising monosaccharides and disaccharides, trisaccharides and higher saccharides,    nanofiltration of the saccharide solution at a temperature in the range of 60° C. to 100° C. obtaining a syrup essentially comprising disaccharides, trisaccharides and higher saccharides,    recovering said syrup,    optionally recycling the permeate resulting from the nanofiltration step to the enzymatic reaction.    
     
     
         2 . A method according to  claim 1 , wherein the substrate comprises at least one monosaccharide type.  
     
     
         3 . A method according to  claim 1 , wherein the substrate is a mixture of at least two different monosaccharide types.  
     
     
         4 . A method according to any of claims  1 - 3 , wherein the monosaccharide type is selected from glucose, fructose, galactose, UDP-galactose, mannose, xylose, and arabinose.  
     
     
         5 . A method according to  claim 3 , wherein the mixture comprises glucose and fructose.  
     
     
         6 . A method according to  claim 5 , wherein fructose is from 40% to 50% and glucose is from 46% to 56%, preferably fructose is from 42% to 46% and glucose is from 50% to 54%.  
     
     
         7 . A method according to  claim 1 , wherein the substrate is liquefied starch or maltodextrins.  
     
     
         8 . A method according to  claim 1 , wherein the substrate is a disaccharide, such as sucrose or lactose.  
     
     
         9 . A method according to any of the preceding claims, wherein the enzymatic reaction is conducted with immobilised enzymes.  
     
     
         10 . A method according to  claim 9 , wherein the enzymes are entrapped in a particle with a semipermeable membrane.  
     
     
         11 . A method according to any of claims  1 - 8 , wherein the enzymes are soluble enzymes and the enzymatic reaction is conducted in a membrane reactor separating the saccharide solution from the enzymes.  
     
     
         12 . A method according to any of the preceding claims, wherein the enzymatic reaction is conducted at a temperature from 60° C. to 100° C., preferably 63° C. to 80° C., more preferably from 65° C. to 75° C.  
     
     
         13 . A method according to any of the preceding claims, wherein the enzymes are heatstable enzymes.  
     
     
         14 . A method according to any of the preceding claims, wherein the enzymatic reaction is a reverse hydrolysis reaction.  
     
     
         15 . A method according to  claim 14 , wherein the enzyme is selected from the group consisting of glucoamylase, α-glucosidase, β-glucosidase (cellobiase), β-galactosidase, α-galactosidase, xylobiase, β-mannosidase, α-mannosidase.  
     
     
         16 . A method according to any of the preceding claims, wherein the enzymatic reaction is a transferase reaction.  
     
     
         17 . A method according to  claim 16 , wherein the enzyme is selected from the group consisting of fructosyltransferase, dextransucrase, transglucosidase, sialyltranferase, and fucosyltransferase.  
     
     
         18 . A method according to any of the preceding claims, wherein the oligosaccharide syrup is a disaccharide syrup.  
     
     
         19 . A method according to  claim 18 , wherein the disaccharide syrup is selected from the group consisting of isomaltose syrup and gentobiose syrup.  
     
     
         20 . A method according to  claim 19 , wherein the isomaltose concentration in the saccharide solution is from 5% to 30%, preferably from 10% to 20%.  
     
     
         21 . A method according to any of claims  18 - 20 , wherein the ratio of disaccharide to total dry substance in the syrup recovered is from at least 40%, preferably at least 50%, most preferably at least 70%.  
     
     
         22 . A method according to any of the claims  1 - 17 , wherein the oligosaccharide syrup comprises a mixture of oligosaccharides having a degree of polymerization from 2 to at least 10, preferably 2 to 6.  
     
     
         23 . A method according to any of the preceding claims, wherein the nanofiltration step comprises diafiltration.  
     
     
         24 . A method according to any of the preceding claims, wherein nanofiltration is operated at a pressure of 10-30 atm.  
     
     
         25 . A method according to any of the preceding claims, wherein nanofiltration is operated at a temperature in the range of 63° C. to 90° C., preferably 65° C. to 80° C.  
     
     
         26 . A method according to any of the preceding claims, which is a continuous method.  
     
     
         27 . A method according to any of the  claims 1  to  25 , which is conducted as a batch method.  
     
     
         28 . A method according to any of the preceding claims, wherein the recycled permeate is subjected to reverse osmosis to remove water before the permeate enters the enzymatic reaction.  
     
     
         29 . A method according to any of the preceding claims, wherein the ratio by weight of monosaccharides to total dry substance in the permeate is at least 80%, preferably at least 90%.  
     
     
         30 . A method according to  claim 5  or  6 , wherein the permeate comprises at least 55% fructose on basis of total dry substance in the permeate.  
     
     
         31 . A system for producing a oligosaccharide syrup comprising 
 an enzyme reactor ( 1 ) having at least one inlet and at least one outlet and means for controlling the temperature in the tank,    means ( 4 ) for passing saccharide solution from the reactor outlet(s) to at least one nanofiltration unit ( 2 ),    at least one nanofiltration unit ( 2 ) having a nanofiltration membrane dividing the nanofiltration unit ( 2 ) into an entrance side having at least one inlet and at least one outlet ( 3 ), and an exit side having at least one outlet ( 5 ), and having means for controlling the pressure applied to the membrane,    optionally means for recycling material from an outlet ( 5 ) of the exit side of the nanofiltration unit ( 2 ) to the enzyme reactor ( 1 ).    
     
     
         32 . A system according to  claim 31 , wherein the enzyme reactor ( 1 ) is a membrane reactor.  
     
     
         33 . A system according to  claim 31 , wherein the enzyme reactor ( 1 ) is a column reactor.  
     
     
         34 . A system according to any of the claims  31 - 33 , wherein the nanofiltration unit ( 2 ) is operated as a diafiltration unit.  
     
     
         35 . A system according to any of the claims  31 - 34 , wherein means for reverse osmosis ( 7 ) is provided downstream of the nanofiltration unit ( 2 ) in the means for recycling material to the enzyme reactor ( 1 ).  
     
     
         36 . A disaccharide syrup obtainable by the method according to any of the claims  1 - 29 , wherein the ratio by weight of disaccharide to total dry substance is from at least 40%, preferably at least 50%, most preferably at least 70%, and the ratio by weight of monosaccharide to total dry substance is from 0.5% to 30%, preferably 0.5% to 20%, most preferably 0.5% to 10% the balance being trisaccharides and higher saccharides.  
     
     
         37 . A disaccharide syrup according to  claim 36 , wherein the composition is as follows:  
       
         
           
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   % DP x  on dry substance 
                 
                     
                     
                 
                     
                 
                 
                 
                 
               
                     
                   monosaccharides (DP1) 
                    0.5-30% 
                 
                     
                   disaccharides (DP2) 
                     50-99% 
                 
                     
                   trisaccharides (DP3) 
                   0.01-20% 
                 
                     
                   higher saccharides (DP4+) 
                   0.01-10% 
                 
                     
                     
                 
                     
                     
                 
             
                
                
                
                
               
               
                
               
            
             
                
                
                
                
                
                
               
            
           
         
       
     
     
         38 . A disaccharide syrup according to claims  36  or  37 , wherein the disaccharide is isomaltose.  
     
     
         39 . A disaccharide syrup according to  claim 38 , wherein the syrup comprises at least 40% isomaltose, preferably at least 50% isomaltose, more preferably at least 70% isomaltose.  
     
     
         40 . An oligosaccharide syrup obtainable by the method according to any of the claims  1 - 29 , wherein the ratio by weight of monosaccharide to total dry substance is at most 10%, preferably at most 5% and the ratio by weight of saccharides having a polymerization degree from 2 to 6 to total dry substance is at least 90%.  
     
     
         41 . A method of producing at least 55% pure fructose, comprising the steps of: 
 enzymatic reaction of glucose and fructose at a temperature in the range of 50° C. to 80° C. obtaining a saccharide solution comprising glucose and fructose, and disaccharides, trisaccharides and higher saccharides,    nanofiltration of the saccharide solution at a temperature in the range of 60° C. to 80° C. obtaining a syrup essentially comprising disaccharides, trisaccharides and higher saccharides,    recovering said syrup, and recovering the permeate resulting from the nanofiltration step.