Process for enzymatic hydrolysis of lignocellulosic material and fermentation of sugars

A process for preparation of a sugar product from ligno-cellulosic material, comprising:

• enzymatic hydrolysis, in a reactor, of ligno-cellulosic material using an enzyme composition comprising at least two cellulases and whereby the enzyme composition at least comprises GH61;
• wherein:
• the enzymatic hydrolysis occurs for a first part of time and a subsequent second part of time;
• and
• (i) during the first part of time oxygen is added to the ligno-cellulosic material to maintain a concentration of dissolved oxygen in the range of 0.02 mol/m3 to 0.12 mol/m3, during the second part of time the concentration of dissolved oxygen is at a concentration at least 50% less than during the first part of time, and the first part of time is 2% to 80% of the total enzymatic hydrolysis time;
• or
• (ii) during the first part of time dissolved oxygen in the ligno-cellulosic material is at a concentration that is at least 50% less than during the second part of time, during the second part of time oxygen is added to the ligno-cellulosic material to maintain a concentration of dissolved oxygen in the range of 0.02 mol/m3 to 0.12 mol/m3, and the second part of time is 2% to 80% of the total enzymatic hydrolysis time;
• and
• dissolved oxygen is measured under normal atmospheric pressure and at about 62° C.;
• the reactor has a volume of 1 m3 or more;
• and
• the ligno-cellulosic material has a dry matter content of 10 wt % or more.