A method of controlling the rate of cellulose hydrolysis, comprising: providing lignocellulosic biomass at a first pressure greater than atmospheric pressure, comprising: a first solid fraction comprising: cellulose; and lignin; and a first liquid fraction; separating said first solid fraction from said first liquid fraction; mixing said first solid fraction with water to form a slurry; wherein said slurry has a pH of pH 3.0 to pH 4.5; increasing said pH of said slurry by 0.5 pH units to 5.0 pH units to form an adjusted pH slurry; optionally, pre-heating said adjusted pH slurry to a temperature less than the critical point of water; contacting said adjusted pH slurry with a second reaction fluid comprising supercritical or near-supercritical fluid to form a reaction mixture comprising: a second solid fraction comprising: lignin; and a second liquid fraction comprising: a soluble C 6 saccharide selected from the group consisting of cello-oligosaccharides, glucose, galactose, mannose, fructose, and mixtures thereof; wherein said supercritical or near-critical fluid comprises water and, optionally, CO 2; and wherein said contacting said adjusted pH slurry with said second reaction fluid has a duration greater than 2 seconds; optionally, reducing the temperature of said reaction mixture to a temperature below 280°C; and optionally, hydrolyzing said second liquid fraction to form a C 6 saccharide selected from the group consisting of C 6 oligosaccharide having lower mer units, glucose, galactose, mannose, fructose, and mixtures thereof. providing lignocellulosic biomass at a first pressure greater than atmospheric pressure, comprising: a first solid fraction comprising: cellulose; and lignin; and a first liquid fraction; a first solid fraction comprising: cellulose; and lignin; and cellulose; and lignin; and a first liquid fraction; separating said first solid fraction from said first liquid fraction; mixing said first solid fraction with water to form a slurry; wherein said slurry has a pH of pH 3.0 to pH 4.5; increasing said pH of said slurry by 0.5 pH units to 5.0 pH units to form an adjusted pH slurry; optionally, pre-heating said adjusted pH slurry to a temperature less than the critical point of water; contacting said adjusted pH slurry with a second reaction fluid comprising supercritical or near-supercritical fluid to form a reaction mixture comprising: a second solid fraction comprising: lignin; and a second liquid fraction comprising: a soluble C 6 saccharide selected from the group consisting of cello-oligosaccharides, glucose, galactose, mannose, fructose, and mixtures thereof; wherein said supercritical or near-critical fluid comprises water and, optionally, CO 2; and wherein said contacting said adjusted pH slurry with said second reaction fluid has a duration greater than 2 seconds; a second solid fraction comprising: lignin; and lignin; and a second liquid fraction comprising: a soluble C 6 saccharide selected from the group consisting of cello-oligosaccharides, glucose, galactose, mannose, fructose, and mixtures thereof; a soluble C 6 saccharide selected from the group consisting of cello-oligosaccharides, glucose, galactose, mannose, fructose, and mixtures thereof; wherein said supercritical or near-critical fluid comprises water and, optionally, CO 2; and wherein said contacting said adjusted pH slurry with said second reaction fluid has a duration greater than 2 seconds; optionally, reducing the temperature of said reaction mixture to a temperature below 280°C; and optionally, hydrolyzing said second liquid fraction to form a C 6 saccharide selected from the group consisting of C 6 oligosaccharide having lower mer units, glucose, galactose, mannose, fructose, and mixtures thereof.