Subcritical hydrolysis of defatted meal of crambe seed: A strategy for the full use of the matrix

Abstract

This work investigated the subcritical water hydrolysis (SWH) of defatted crambe seed meal to obtain total reducing sugars (RS), fermentable sugars (FS) and platform chemical products (PC). For this purpose, the experiments evaluated the effect of temperature (180, 200 and 220 °C) and pressure (5, 10 and 15 MPa) of the process conducted in semi-continuous mode. The results obtained indicate that the temperature of 180 ºC allowed the obtaining of RS and FS, while the higher PC contents are the result of the increase in this variable. Pressure influenced, in isolation, only the obtaining of FS, requiring synergy with temperature to obtain the other products. The dry hydrolysates presented xylose and glucose as predominant FS, and levulinic acid as PC. The FT-IR data demonstrated that the SWH process is efficient for the conversion of biomass into FS and PC, allowing the production of compounds with higher added value. The characterization of the residual biomass (RB) indicated the solubilization of phytochemicals into the hydrolysate, and the loss of its color suggests degradation due to the occurrence of the Maillard reaction of the residual constituents. Additionally, organic acids were identified by FT-IR and the characterization of RB demonstrated relative bioherbicidal potential, in addition to the possibility of thermochemical conversion for energy production, consolidating the concept of biorefinery to the matrix in question.