Xylobiose

Xylobiose is a disaccharide composed of two β-D-xylopyranose units linked by a β(1→4) glycosidic bond. It is formed from the pentose sugar xylose, with the two xylose residues giving the overall formula C10H18O9 and a molecular weight near 282 g/mol. The linkage joins the C1 carbon of one xylose to the C4 carbon of the other; the reducing end is the anomeric carbon of the terminal xylose, making xylobiose a reducing sugar.

In nature and industry, xylobiose arises during the enzymatic breakdown of xylan, a major component of plant hemicellulose. Xylan degradation by xylanases and β-xylosidases produces xylobiose as an intermediate, which can then be hydrolyzed to two molecules of xylose by β-xylosidase. Xylobiose is typically found in xylan-derived hydrolysates and in dietary fiber-containing materials where partial xylan digestion has occurred.

Properties of xylobiose include its water solubility and its status as a reducing sugar, capable of participating in reactions typical of reducing carbohydrates. In research contexts, xylobiose serves as a substrate for studying β-xylosidase activity and as a model compound in studies of xylan degradation and microbial fermentation. It is not commonly used as a sweetener compared with other sugars due to its relatively modest sweetness and specific metabolic handling.