Carbohydrate behaviour of Arundo donax L. in ethanol±alkali medium of variable composition during organosolv deligni®cation Anatoly A. Shatalov * , Helena Pereira Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade Te Âcnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa Codex, Portugal Received 22 May 2001; accepted 1 October 2001 Abstract The effect of medium alkalinity, organic solvent concentration and liquor-to-material ratio on the main carbohydrate constituents of Arundo donax L. stem cellulose, hemicelluloses and uronic acids) under conditions of ethanol±alkali deligni®cation has been examined. A protective action of alcohol addition against carbohydrate degradation was observed. The amount of non-cellulosic polysaccharides as well astheintrinsicviscosityofpulpsincreasedwithariseinethanolcontentinthereactionmixture.Theincreaseinmediumalkalinitywasfound to have a detrimental effect on carbohydrates and caused substantial loss of hemicelluloses. Elevated alkali and solvent concentrations were found to favour uronic acid groups degradation and hexenuronic acid formation during ethanol±alkali pulping. The liquor-to-material ratio had only some effect on uronic acid behaviour without any appreciable in¯uence on cellulose and hemicelluloses. q 2002 Elsevier Science Ltd. All rights reserved. Keywords: Arundo donax L; Ethanol±alkali pulping; Carbohydrate degradation; Uronic acid groups; Hexenuronic acids 1. Introduction The use of alternative non-wood sources of®bre in paper- making has received substantial attention. There are two important reasons for the continuous interest in this area. Firstly, there is a decrease in wood availability with the increasing demand for market pulp in some rapidly devel- oping countries in Asia, Africa and Latin America. Secondly, the current overproduction of food in the Western European countries has stimulated a search for new non- food crops for industrial utilisation Moore, 1996; Leminen, Johansson, Lindholm, Gullichsen, & Yilmaz, 1996). Arundo donax L. or giant reed) is a widely distributed perennial rhizomatous grass. The high degree of adaptabil- ity to different ecological conditions Perdue, 1958), annual harvesting period and high biomass productivity Dalianis, Sooter, & Christou, 1994) make Arundo donax of interest as a ®bre crop for pulp and paper production. The ®rst comparative experiments on organic solvent based deligni®cation so-called `organosolv' pulping) of Arundo donax showed the potential of this approach for the production of high quality non-wood ®bres Shatalov & Pereira, 2000, 2001a). The more promising results were obtained by ethanol reinforced alkaline pulping ethanol± soda or ethanol±alkali pulping). First tested on softwoods Nakano, Daima, Hosoya, & Ishizu, 1981), the ethanol± alkali pulping was successfully applied to such crops as bagasse and wheat straw Liang, Zhou, Xiao, & Wang, 1988). In the present paper, we present the results on the in¯u- ence of reaction medium composition on the carbohydrate complex of A. donax L. reed under conditions of ethanol± alkali deligni®cation. 2. Experimental 2.1. Material The stems of A. donax L. reed were supplied by the Agri- cultural University of Athens, Greece Plant Production Department) in short culms, free from leaves. For pulping experiments the stems were disintegrated manually to a size of approximately 1±1.5 cm length, 2±3 mm width. The humidity of the material was determined. 2.2. Methods 2.2.1. Organosolv deligni®cation Ethanol±alkali pulping of Arundo donax was carried out in 100-ml stainless steel autoclaves rotated in an oil bath Carbohydrate Polymers 49 2002) 331±336 0144-8617/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved. PII: S0144-861701)00340-X www.elsevier.com/locate/carbpol * Corresponding author. Tel.: 1351-21-363-4662; fax: 1351-21-364- 5000. E-mail address: anatoly@isa.utl.pt A.A. Shatalov).