Simultaneous saccharification and fermentation residues as potential sources of phenolics by fast pyrolysis (Py-GC/MS) and alkaline hydrolysis

Abstract

Unlike 1 G bioethanol, the success of 2 G technology faces difficulties. The economic difficulties of 2 G bioethanol can be solved with an additional income in by-products, mainly from lignin. The present study investigated the generation of phenolics via fast pyrolysis and alkaline hydrolysis using residues from saccharification and simultaneous fermentation (SSF) as substrate. The SSF residues were obtained from schemes with green coconut fiber (without chemical pretreatment) and corn cob (with previous acid pretreatment). Chemical composition, FTIR, and XRD analyses confirmed that the processing undergone by SSF residues altered the lignocellulose structure. Due to extractives removal and lignin increase, the fast pyrolysis experiments with SSF residues favored the generation of phenolics over C1-C4 products. Phenol was the main product in the pyrolysis of untreated green coconut fiber (14.64%) and SSF residue (13.51%), while the 2-methoxy-4-vinylphenol content in the bio-oil was doubled with the SSF corn cob residue (from 12.87% to 27.01%). SSF corn cob residue showed a high yield of hydroxynamic acids after alkaline hydrolysis with sodium hydroxide. The p-coumaric acid yield reached 4337 mg/100 g in experiments at 60 °C. Based on the results, the conversion of SSF residues appears as an alternative to obtain commercially appealing phenolics and may be attractive for 2 G bioethanol technology.