Abstract:Liquorice residue, the residue of liquorice after the extraction of active ingredients, is rich in lignocellulose. The liquorice residue was pretreated with two dilute basic solutions (Na2CO3 aqueous solution and NaOH aqueous solution) and the mixtures of dilute basic solution (Na2CO3 aqueous solution or NaOH aqueous solution) and ethanolamine acetate, and the effects of different base concentrations and pretreatment temperatures on the composition and enzymatic hydrolysis of liquorice residue were studied. The results showed that the lignin removal reached 54.1% and cellulose recovery rate was 77.2% when the liquorice residue was pretreated with 2% (mass fraction) NaOH aqueous solution with a solid-liquid ratio (w/v) of 1:10 (i.e., 10 ml of solvent per gram of liquorice residue) for 1.5 h at 100 ℃, and the glucose yield was 53.5% after 24-h enzymatic digestion which was 4.0 times higher than that without pretreatment (10.6%). When the pretreated liquorice residue was subjected to high solid enzymatic digestion at a solid-liquid ratio of 3:10 with an enzyme dosage of 45 FPU/g of biomass for 72 h, the glucose concentration reached 86.2 g/L and xylose was 18.9 g/L. Using this hydrolysate as the carbon source for fermentation, the total production of 2,3-butanediol and acetoin was 43.9 g/L after 96-h fermentation, and the conversion rate was 0.42 g/g. Compared with the control group, the hydrolysate was more favorable to the growth of the bacteria, and the productivity of 2,3-butanediol and acetoin was increased, while the conversion rate was slightly lower.