Compositions of Monomeric Sugars in Some Nigerian Hardwoods

Abstract

Compositional analysis of monomeric sugars in carbohydrate fractions of 10 African angiosperms has been carried out using acid hydrolysis and high performance anion exchange chromatography with borate post column derivatization (HPAEC-Borate). The monomeric sugars in the wood stems were dominated by glucose, primarily from the cellulosic fraction of the biomasses. Xylose and small fractions of mannose constituted the main sugars from the hemicellulose fractions. The concentration of glucose peaked at 510 mg/g (dry sample) in Sterculiar rhinopetala, the lignocellulose with the least concentration of mannose among the samples. The ratio of the xylose to 4-O-methylglucuronic acid in Terminalia ivorensis suggested that this sample has more acidic xylan than Trilepsium madagascariensis, the sample with the richest xylan content (15 wt. %). The concentration of arabinose, rhamnose and galactose were mostly below 10 mg/g (dry sample) in all samples. The analysis of the non holocellulosic fractions of the samples revealed high lignin contents, which ranged 19.4 wt. % - 33.8 wt. % and high extractive contents, ranged between 1.8 wt. % and 11.0 wt. % (on dry basis).

Keywords:Biomass, Extractives, Hardwoods, Lignin, Monomeric sugar, Polysaccharide