Lignocellulosic biomasses such as banana pseudostem are attractive cellulose sources for bioenergy production, and for the use in biorefinery processes. However, pretreatment of lignocellulosic material is required to remove hemicellulose and lignin, while increasing cellulose accessibility to enzymatic hydrolysis (i.e., decreasing biomass recalcitrance). The effect of different concentrations of acid (H 2 SO 4), alkaline (NaOH) and peroxide (H 2 O 2) pretreatments on the chemical composition, cellulose accessibility, and enzymatic digestibility of banana pseudostem were studied. The water insoluble solids (WIS) recovery was low (∼30%) for the severe pretreatment conditions applied, indicating high material solubilization. Acid pretreatment completely removed the hemicellulose content, whereas alkaline and peroxide pretreatments reduced its amount to 4.38 and 8.68%, respectively. In contrast, the lignin content increased (from 17.26 to 39.99%) after severe acid pretreatment, while alkaline and peroxide pretreatments reduced the lignin content to 7.65% and 7.17%, respectively. In line with hemicellulose and lignin removal, the cellulose content increased from 60.84 to 75.48 and 74.37%, respectively for alkaline and peroxide pretreatments, with no alteration for acid. Dye adsorption assays showed that alkaline and acid pretreatments resulted in high internal and external specific surface areasindicative of high cellulose accessibilitywhen compared with peroxide pretreatments. Overall, alkaline and acid pretreatments resulted in the highest glucose yields from enzymatic hydrolysis of banana pseudostem, compared with peroxide pretreatment. In conclusion, concentrations of each pretreatment that led to the highest glucose yields was identified, confirming that the banana pseudostem is a great source of fermentable sugars, with high potential for biofuel production.

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BACKGROUNDSugarcane bagasse is a heterogeneous and organized material that needs a pretreatment to access the polysaccharides (cellulose and xylan). The particle size of a non‐milled bagasse can influence the xylan and xylose solubilization, as well as the enzymatic hydrolysis of the pretreated material. Using bagasse selected on 16‐, 30‐, 40‐ and 50‐mesh sieves: xylan solubilization was performed with hydrogen peroxide; xylose was solubilized with diluted sulfuric acid; and enzymatic hydrolysis was conducted for glucose yield evaluation.RESULTSThe xylose solubilized by acid pretreatment resulted in a maximum of 6.59 g L−1 with no influence of particle size. The solubilized xylan showed linear correlation with a variation of 36.18% (16‐mesh bagasse) to 71.43% (<50‐mesh bagasse). Pretreated material submitted to enzymatic hydrolysis revealed that particle size influenced the pretreatment, increasing the glucose yield.CONCLUSIONSThe results showed that non‐milled sugarcane bagasse particle size selection positively influenced the solubilization of xylan, improving the enzymatic hydrolysis of the pretreated material. © 2020 Society of Chemical Industry (SCI)

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