Optimization and kinetic analysis of untreated brewers’ spent grain saccharification process via enzymatic hydrolysis

The enzymatic hydrolysis of dried brewers' spent grain without being pretreated was investigated in this work. The enzymatic hydrolysis experiments were carried out using Cellic (R) CTec2 as enzymatic complex and the glucose yield was optimized with respect to temperature, solid loading and enzyme loading. The optimization of enzymatic hydrolysis obtained through the response surface methodology was validated experimentally resulting in a glucose yield of 11.71 +/- 0.09 g(glucose) g(DM)(-1) at 48.6.C, 6.7 % w/w biomass loading, and 0.22 mL g(DM)(-1) as enzyme concentration. The glucose yield obtained corresponds to 44 % of the theoretical one. The temporal profile of glucose concentration was modeled by using the Chrastil's model, and by a modified version of its classical formulation. The models were compared with respect to the fit goodness and precision of parameter estimation. Even if both models were able to properly describe the transient behavior, the proposed modified Chrastil's model provided a more precise parameter estimation compared to the classical one.