Switchable ionic liquids for biomass pretreatment and enzymatic hydrolysis

A method for preparing a sugar composition, the method comprising:

• i) forming a mixture comprising polysaccharide biomass and an ionic liquid solution, wherein
• the ionic liquid solution comprises water and an ionic liquid,
• the ionic liquid comprises a dicarboxylic acid anion and a cation,
• the pH of the mixture is greater than or equal to about 10, and
• the molar ratio of the dicarboxylic acid anion to the cation is at least about 1:2;
• ii) maintaining the mixture under conditions sufficient to dissolve at least a portion of the polysaccharide present in the polysaccharide biomass;
• iii) reducing the pH of the mixture containing the dissolved polysaccharide to at least about 7;
• iv) adding at least one glycoside hydrolase to the mixture having the reduced pH;
• and
• v) maintaining the mixture containing the glycoside hydrolase under conditions sufficient to hydrolyze at least a portion of the dissolved polysaccharide, thereby forming the sugar composition;
• wherein the sugar composition comprises at least one monosaccharide or oligosaccharide.