Fermented Cassava Residue Lignin Prepared by Sequential Acid Steam-Explosion and Hot-Alkaline Treatment and Its Antioxidant Properties

摘要

Fermented cassava residue (FCR) is a solid waste generated in cassava-based ethanol production that constitutes a major environmental challenge and wastes a natural resource. In the present study, a process involving sequential acid steam-explosion and hot-alkaline treatment was developed to prepare an antioxidant lignin in high yield and purity from FCR. Two-dimensional NMR analysis indicates that FCR lignin belongs to a guaiacyl/syringyl/hydroxyphenyl (G/S/H) class of lignin. ~(31)P NMR analysis, after hydroxyl group phosphorylation, indicates that phenolic hydroxyl in FCR lignin attributable to mostly G-OH. One FCR lignin (No. 3) possessed the antioxidant activity similar to that of butylated hydroxytoluene. This FCR lignin may have potential applications as a food antioxidant or in other industrial processes as an antioxidant.