A process for manufacturing xylose by extracting hemicellulose from a cellulosic material, such as by a cold caustic extraction method, concentrating the extract, such as by nanofiltration, into a hemicaustic stream containing hemicellulose with greater than about 85 wt % xylan content, and subsequently hydrolysing the xylan from the hemicaustic stream to xylose. The high concentration of xylan within the concentrated hemicaustic stream enables hydrolyzation of the xylan to food-grade xylose and, optionally, hydrogenation of the xylose to xylitol without the need of a chromatographic separation step as previously required.