Characterizations and application potentials of the hemicelluloses in waste oil-tea camellia fruit shells from Southern China

Oil-tea camellia fruit shell (CFS) is a considerable waste lignocellulosic resource. The current treatment of these wastes are composting and burning. Burning may pose a threat to air and since CFS contains 5-14% saponins, the composting may lead to water foaming and toxicity. CFS contains a large amount of hemicelluloses, which has the potential to be extracted and valorized. The chemical structures of CFS hemicelluloses have not been extensively analyzed, which limits their application. In this study, hemicelluloses were extracted by dimethyl sulfoxide and alkali solution from eight species of CFS in Southern China. The detailed compositional and structural characteristics of the separated hemicellulose components were studied. The content of hemicelluloses in CFS ranges from 40% to 55%. The hemicelluloses consist of L-rhamnose, L-arabinose, L-fucose, D-xylose, D-mannose, D-glucose, D-galactose and D-glucuronic acid units, among which xylose is the major component. The existence of the sugars that are rare in lignocellulosic materials, i.e. fucose and rhamnose, are confirmed as the minor components. From 2D NMR analysis, the major chemical structures/types of CFS hemicelluloses are found to be L-arabinose-4-O-methyl-alpha-D-glucuronic acid-D-xylose and galacto-glucomannan. The application potentials of the CFS hemicelluloses in fine chemicals were evaluated.