LİGNOSELÜLOZİK MATERYALDEN SUBKRİTİK ŞARTLARDA HİDROTERMAL YÖNTEMLE LAKTİK ASİT ÜRETİMİ
Project no. 655 · Status: Kapanmış · 2017
Summary
The studies were carried out in three stages as a biorefinery approach, liquid hot water pretreatment, enzymatic hydrolysis and fermentation. In the first stage, the lignocellulosic liquid, which has a robust structure was pretreated with liquid hot water pretreatment. By the pretreatment, lignin in biomass content was removed and fermentable sugars were obtained from hemicellulose and cellulose. After pretreatment, two phases of the sample were obtained as solid (raffinate) and liquid (hydrolyzate). Optimization of pretreatment was created using the D-optimal experimental design in the Design Expert 7.0 program. According to experimental design results, optimum conditions for temperature, pressure and retention time were determined as 153 ° C, 153 bar and 50 minutes, respectively. After the pretreatment, the highest reducing sugar content in the hydrolyzate fraction of the biomass was 77 mg / g. After pretreatment, enzymatic hydrolysis was applied to the solid (raffinate) fraction. Optimization for the enzymatic hydrolysis step, the Design Expert 7.0 program was created using the Box-Behnken experimental design. According to experimental design results, optimum conditions for solid / liquid ratio, enzyme amount, retention time were determined as 5% (w / v), 20 FPU / ml, 72 hours, respectively. In enzymatic hydrolysis process, the highest amount of reducing sugar was found to be 200 mg / g. In the lactic acid fermentation stage, the liquid (hydrolyzate) obtained after pretreatment was obtained by submerged fermentation by using 'Rhizopus oryzae’ fungi. The highest lactic acid content was found to be 6.8 g / L at 24 hours and the lactic acid yield was 0.28 g / l.h