The present invention provides a method for extracting polymeric pentose, preferably xylan, from a polymeric pentose containing liquid/slurry, preferably black liquor, comprising the following steps: a) providing a polymeric pentose containing liquid/slurry; b) concentrating the polymeric pentose by membrane separation of a said polymeric pentose containing liquid/slurry; and c) adding alcohol to the concentrate obtained in step b) and subsequently acidifying said concentrate obtained in step b) for precipitating polymeric pentose whereby a polymeric pentose product, or an intermediate polymeric pentose product, is obtained. In this above way polymeric pentose, e.g. xylan, is separated whereby the use of methanol (less lignin must be kept in solution) and acid (less acid which buffers the pH-decrease) become much lower. The present invention also provides according to a second aspect a polymeric pentose product or an intermediate polymeric pentose product obtainable by the method according to the first aspect. The present invention also provides according to a third aspect use, preferably for the production of food additives or as chemical feed stock, of the polymeric pentose product or the intermediate polymeric pentose product of the second aspect of the invention.