Optimization of high-solid enzymatic hydrolysis of two-step alkaline and dilute acid-pretreated sugarcane bagasse at low enzyme loadings by response surface methodology

Sugarcane bagasse-a lignocellulosic material derived from sugarcane after crushing and extracting of its juice-is a promising feedstock for bioethanol production. The current study presented a two-step alkaline and acid pretreatment of sugarcane bagasse using sodium hydroxide and maleic acid as a strategy to enhance enzymatic digestibility of sugarcane bagasse. The two-step alkaline and acid pretreatment resulted to a significant increase in glucan content (69.72%) with accompanying decreases in xylan (12.99%) and lignin (4.89%) contents. Preliminary study on enzymatic hydrolysis of the two-step alkaline and acid-pretreated sugarcane bagasse with low solid loading and low cellulase concentrations resulted to high glucose yields. Optimization of high-solid enzymatic hydrolysis of two-step alkaline and acid-pretreated sugarcane bagasse was executed based on Box-Behnken design (BBD). BBD-a response surface methodology-is a powerful method that can be used to test several parameters by applying a minimum number of experimental trials. The optimal level of process variables as indicated by the statistical model namely solid loading (20%, w/w), incubation time (72 h), enzyme loading (2 FPU/g glucan), and substrate feeding (mode 2) were validated. Optimization of the process parameters resulted to 61.85% of glucose yield which was close to its predicted value (65.71%). The current study highlights the potential of high-solid enzymatic hydrolysis using two-step alkaline and acid-pretreated sugarcane bagasse for efficient fermentable sugar production.

Automated summary

This study optimized the enzymatic digestibility of sugarcane bagasse through a two-step alkaline and acid pretreatment, resulting in high glucose yields. The process parameters were optimized using response surface methodology, and the glucose yield achieved was close to the predicted value. This study highlights the potential of efficient fermentable sugar production from sugarcane bagasse.