Valorization of andiroba (Carapa guianensis Aubl.) residues through optimization of alkaline pretreatment to obtain fermentable sugars

Abstract

The residual peels of andiroba seeds were submitted to alkaline pretreatment that aimed to maximize the recovery of fermented sugar. Evaluation of the best operation performance via the reaction time variables (20, 60, and 100 min), NaOH concentration (2, 3, and 4% (m/v)), and temperature (60, 90, and 120 °C) at a fixed solids concentration of 5% (m/v) was performed. A Box-Behnken experimental design was used. Lignocellulosic material was characterized by cellulose (30.57 ± 1.00%), hemicellulose (15.08 ± 0.65%), lignin (36.02 ± 1.05%), extractives (7.49 ± 0.03%), and ash (1.53 ± 0.28%). The optimization was performed using the response surface methodology approach. The model provided a coefficient of determination (R2) of 0.95. The predicted optimal conditions for the process were a reaction time of 100 min, NaOH concentration of 4% (m/v), and temperature of 120 °C, which allowed the authors to obtain a saccharification of approximately 47.9%.