13-08: Enzymatic liquefaction and saccharification of sugar beet leaves for biofuel production

High solids processing holds great potential to improve the cost- and energy-efficiency of ethanol production. However, working with high solid streams presents challenges for transportation and mixing operations. Liquefaction and saccharification steps can overcome these challenges by improving rheological properties and converting structural polysaccharide in the biomass into fermentable sugars and other compounds. Sugar beets form the basis for greater than 30% of the world’s sugar production leaving sugar beet leaves (40-50% (wet basis) of total crop biomass) remains underused. This study developed an enzymatic liquefaction and saccharification process to convert sugar beet leaves into amendable liquefied stream for ethanol fermentation. Enzymatic liquefaction and saccharification of the sugar beet leaves was investigated at 12% and 6% total solids (TS) content, using a mix of cellulases, β-galactosidases, hemi-cellulases and pectinases. Optimal enzyme loadings were investigated. Under a selected enzyme loading, the result shows a fast liquefaction within 24 h. Hydrolysis of sugar beet leaves took less time at the lower TS content (6%). Reducing sugar concentration and yield reached the maximum in 3 days for 6% TS (14.4 g/L and 23.4% g/g TS, respectively) but in 7 days for 12% TS (27.8 g/L and 22.7 % g/g TS, respectively), which is approximately 120% increase in the yield by enzyme addition. The results will be very useful for designing the pretreatment processes for conversion of sugar beet leaves or similar biomass materials for biofuel and biochemical production.