Xylose

An aldose monosaccharide comprising five carbon atoms, a pentose sugar that may be produced by hydrolysis of xylan from straw, hardwoods, and corn cobs. It is the building block of hemicellulose and therefore one of the most abundant sugars in plant biomass, and it serves as the substrate for manufacture of xylitol by hydrogenation. It is only partly fermented by ordinary baker’s yeast, which matters in bioethanol and brewing from lignocellulosic materials, where engineered yeasts are needed for full conversion. In foods it participates in the Maillard browning reaction faster than glucose, strongly influencing crust colour and flavour in baked goods. Its sweetness is lower than sucrose, and it is used in diabetic and specialty products.