Second-generation ethanol process for integral use of hemicellulosic and cellulosic hydrolysates from diluted sulfuric acid pretreatment of sugarcane bagasse

Ultrasonic-Assisted Dual-Alkali Pretreatment and Enzymatic Hydrolysis of Sugarcane Bagasse Followed by Candida tropicalis Fermentation to Produce Xylitol

“…The common methods of pretreatment of sugarcane bagasse are physical methods, chemical methods, biological methods, and physical-chemical combination methods. Common physical methods such as mechanical activation ( 6 ), microwave treatment ( 7 ), and ultrasonic treatment ( 8 ) mainly increase the surface area of the raw material by changing the physical structure of the lignocellulosic raw materials, while chemical methods mainly use chemical reagents such as acid, alkali, and ionic liquid to make raw materials swell, thereby disrupting the tightly bound structure of hemicellulose, lignin, and cellulose, reducing the crystallinity of cellulose ( 9 ). Alkaline pretreatments, including NaOH, Ca(OH) 2 , and ammonia water pretreatment, can be used to remove lignin from sugarcane bagasse, which generally swells the sugarcane bagasse and reduces the crystallinity of cellulose ( 10 – 12 ).…”

Dilute acid pretreatment for enhancing the enzymatic saccharification of agroresidues using a Botrytis ricini endoglucanase

“…The highest levels of RS were observed in sugarcane bagasse treated with 1.5% acid (911 mg⋅g −1 ), in rice husk with 1% acid (764 mg⋅g −1 ), and wheat bran with 0.5% acid (406.5 mg⋅g −1 ). The use of diluted sulfuric acid caused 89.5% of hemicellulose solubilization and 82% of monomeric sugars production of sugarcane bagasse 22 About 30% of lignin removal was obtained after pretreatment of Napier grass with 3% sulfuric acid 23 The maximum glucose yield (54.5%) was obtained with 0.05% sulfuric acid in acacia wood 24 The highest sugar yield was 66.75% after treatment of coffee‐cut stems with acid pretreatment 25 The lignocellulosic degradation with the use of imidazole was dependent on temperature, and the best result for the recovery of cellulose (62.4% w/w) was obtained at 170°C for 2 h 26 Thus, the lignocellulosic degradation and release of reducing sugar depend on the pretreatments, contents of bases and acid, and biomass.…”

“…The main objective of lignocellulosic biomass pretreatment is to disrupt the lignocellulose complex by partial degradation of hemicellulose and lignin 8 This increases the efficiency of the enzymatic hydrolysis process, through the reduction of the occurrence of crystalline cellulose in favor of amorphous forms, which offers greater accessibility to cellulolytic enzymes 20,12 (Sarkar et al, 2012). In addition, the pretreatment with diluted sulfuric acid also enables the hydrolysis of hemicellulose in xylose, arabinose, galactose, and mannose, 21,11,22,3 which is a determining factor for the validation of the pretreatment efficacy using spectrophotometry 16 In this study, we recorded the release of RS at different concentrations of acid pretreatment (Figure 1). The RS production of the wheat bran was observed in all concentrations of acid, but for sugarcane bagasse, and rice husk, there was no release of RS in the 1% and 1.5% of acid, respectively.…”

Strategies for improved xylitol production in batch fermentation of sugarcane hydrolysate using Saccharomyces cerevisiae

“…Besides being one of the largest crops worldwide, the sugarcane E2G industry is rapidly evolving (Center for Strategic Studies and Management (CGEE), 2017; Dionísio et al, 2021;Lopes et al, 2016), creating opportunities for the manufacturing of other added-value molecules. While prospects for better xylitol productivity have applied fed-batch cultivation (Baptista et al, 2018;Kogje and Ghosalkar, 2017), the use of a non-fed system accounts for a great share of the fermentation system used in the biomass valorization industry, validating such endeavor.…”

“…In this work, we investigate different cultivation conditions for improved xylitol production from sugarcane straw hydrolysate using an engineered S. cerevisiae and batch fermentation - operational condition frequently applied in the Brazilian sugarcane second-generation bioethanol (E2G) industry (Dos Santos et al, 2016). Besides being one of the largest crops worldwide, the sugarcane E2G industry is rapidly evolving (Center for Strategic Studies and Management (CGEE), 2017; Dionísio et al, 2021; Lopes et al, 2016), creating opportunities for the manufacturing of other added-value molecules. While prospects for better xylitol productivity have applied fed-batch cultivation (Baptista et al, 2018; Kogje and Ghosalkar, 2017), the use of a non-fed system accounts for a great share of the fermentation system used in the biomass valorization industry, validating such endeavor.…”