RESUMEN
Oil-tea camellia fruit shell (CFS) is a very abundant waste lignocellulosic resource. The current treatments of CFS, i.e. composting and burning, pose a severe threat on environment. Up to 50 % of the dry mass of CFS is composed of hemicelluloses. However, chemical structures of the hemicelluloses in CFS have not been extensively studied, which limits their high-value utilization. In this study, different types of hemicelluloses were isolated from CFS through alkali fractionation with the assistance of Ba(OH)2 and H3BO3. Xylan, galacto-glucomannan and xyloglucan were found to be the major hemicelluloses in CFS. Through methylation, HSQC and HMBC analyses, we have found that the xylan in CFS is composed of â4)-ß-D-Xylp-(1â and â3,4)-ß-D-Xylp-(1â linked by (1â4)-ß glycosidic bond as the main chain; the side chains are α-L-Fucp-(1â, â5)-α-L-Araf-(1â, ß-D-Xylp-(1â, α-L-Rhap-(1â and 4-O-Me-α-D-GlcpA-(1â, connected to the main chain through (1â3) glycosidic bond. The main chain of galacto-glucomannan in CFS consists of â6)-ß-D-Glcp-(1â, â4)-ß-D-Glcp-(1â, â4,6)-ß-D-Glcp-(1â and â4)-ß-D-Manp-(1â; the side chains are ß-D-Glcp-(1â, â2)-ß-D-Galp-(1â, ß-D-Manp-(1â and â6)-ß-D-Galp-(1â connected to the main chain through (1â6) glycosidic bonds. Moreover, galactose residues are connected by α-L-Fucp-(1â. The main chain of xyloglucan is composed of â4)-ß-D-Glcp-(1â, â4,6)-ß-D-Glcp-(1â and â6)-ß-D-Glcp-(1â; the side groups, i.e. ß-D-Xylp-(1â and â4)-ß-D-Xylp-(1â, are connected to the main chain by (1â6) glycosidic bond; â2)-ß-D-Galp-(1â and α-L-Fucp-(1â can also connect to â4)-ß-D-Xylp-(1â forming di- or trisaccharide side chains.