INTENSIFICATION OF THE FREEZE-THAW PRETREATMENT OF DISINTEGRATED POPLAR WOOD

Thisresearch wasfocused on the effect of water content in the cells of disintegrated Populus nigraL. on a freeze-thaw pretreatment method before an enzymatic hydrolysis. Two chipped andsieved fractions 2.5 mm and0.7 mm and two milled fractions,characterized as 18°SR (Shopper–Riegler index) and 37°SR,of the disintegrated 5 years old poplartree were used for ourexperiment. Glucose and xylose yields were measured after 24 and 48 hours ofenzymatic hydrolysis with a 15% load of the enzyme measured to a total cellulose content. Theinfluence of nine freeze-thaw cycles under -20°C and +20°C was considered. The results showed thatanincrease in moisture content positively affects yields in all fractions but adesirable result was achieved mainly for the 0.7 mm fraction where the total yield increased by about 16%.More effective wayis afiner wetbeating ofwood mass, while wood fibrereceivesmoisture already in the technological process.Thehighest glucan conversion 51,74% and the total hemicelluloses conversion 47,72% was achieved for the finest fraction 37°SR.Thehigher moisture content has a positive effect on the increase in theconversion of oligosaccharides, especially glucan, in chipped fractions.