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Chemical Structures of Cellulose, Hemicelluloses, and Lignin
Published in David N.-S. Hon, Chemical Modification of Lignocellulosic Materials, 2017
Gyosuke Meshitsuka, Akira Isogai
Hemicelluloses in reaction woods are quite different from those in the normal woods, namely, galactan and β-(l–3)-glucan in compression wood and galactan in tension wood. It is also well known that a remarkable amount of a water-soluble polysaccharide, arabinogalactan, is contained in the heartwood of larch. Since this polysaccharide occurs mainly in the lumen of tracheids and is not a cell wall component, it may not be included in hemicelluloses. Although structures and distributions of hemicelluloses have been comprehensively studied in the last 20 years, their physiologic meanings in a cell wall are not known yet. This must be the most important point for the future study of hemicelluloses.
Polysaccharides as Nanomaterials for Therapeutics
Published in Dan Peer, Handbook of Harnessing Biomaterials in Nanomedicine, 2021
Arabinogalactan is a long, highly branched natural polysaccharide composed mostly of galactose and arabinose. Arabinogalactan is extracted mainly from the Larix tree and is available at 99.9% purity with reproducible Mw and physicochemical properties [44]. The unusual water solubility (70% w/w in water), biocompatibility, biodegradability, and ease of drug conjugation in an aqueous medium make arabinogalactan attractive as a potential drug carrier [44].
Rheological, Thermal, Structural, and Chemical Changes during Oxidation of Gum Arabic by Ozone
Published in Ozone: Science & Engineering, 2023
Zeynep Tuğba Özaslan, Şenol Ibanoğlu
Gum Arabic (GA, E404) is an edible sticky substance. It is obtained from the stems of Acacia Senegal and Acacia seyal (Sanchez et al. 2018). Gum tree can be found in arid environments throughout the sub-Saharan African region, from Senegal to East Africa (Cecil 2005). Joint Expert Committee for Food Additives (JEFCA) defined it like “a dried exudation obtained from the branches of A. Senegal (L)” (FAO 1999). It is a negatively charged biopolymer with a highly complex and branched structure containing both amino groups and carboxylic groups (Mariod 2018). The carbohydrate content of GA, which is easily soluble in cold and hot water, consists mostly of D-galactose and D-arabinose units, and this carbohydrate part constitutes about 97% of the total gum. Protein components such as arabinogalactan-protein and glycoprotein constitute less than 3% (w/w) of GA (Ali, Ganie, Mazumdar 2018) (Figure 1). Although GA could be used in textile, ceramics, cosmetics, and pharmaceutical industries, it is extensively utilized as stabilizer, thickener, emulsifier, and encapsulation material in confectionery, bakery products, dairy products, and soft drinks (Sanchez et al. 2018).
Effect of modified starches and gum arabic on the stability of carotenoids in paprika oleoresin microparticles
Published in Drying Technology, 2021
Ana Gabriela da Silva Anthero, Eveling Oliveira Bezerra, Talita Aline Comunian, Fernanda Ramalho Procópio, Miriam Dupas Hubinger
Among the various emulsifiers, carbohydrates, such as gum arabic and modified starches, are widely applied as encapsulant agents for hydrophobic compounds. Gum arabic consists mainly of high molecular weight polysaccharide (D-galactopyranose, L-rhamnose, L-arabinofuranose, and D-galacturonic acid) with protein fractions (arabinogalactan-protein). This hydrocolloid presents high water solubility, capability of forming films and good emulsifying properties as it is widely used to stabilize emulsion containing pigments, flavors, and oils.[11–13] An interesting study demonstrated good protection against carotenoid degradation at 25 °C that was promoted by a blend of gum arabic and maltodextrin (1:1) under water activity between 0.2 and 0.3[14] and good carotenoid retention in powder containing carrot juice.[15]
Plant gums for sustainable and eco-friendly synthesis of nanoparticles: recent advances
Published in Inorganic and Nano-Metal Chemistry, 2020
Gum arabic, a natural polysaccharide derived from exudates of A. senegal and A. seyal trees,[99] is one of the most widely used amphiphilic hydrocolloids in the food industries.[61,100] This gum is well-known for its complex chemical structure composed mainly of a highly branched polysaccharide and two protein–polysaccharide complexes as minor component.[99] Highly branched polysaccharide consisting of β-(1→3) galactose backbone with linked branches of arabinose and rhamnose, which terminate in glucuronic acid (found in nature as magnesium, potassium, and calcium salt). Second part made up arabinogalactan-protein complex in which polysaccharide moieties were linked through both O-serine and O-hydroxyproline.[101] This part of gum arabic is susceptible to bacteria polysaccharide lyase family that is specific for the L-rhamnose-alpha1,4-D-glucuronic acid linkage that caps the side chains of arabinogalactan–protein complex.[102] The third part contains highest protein content (around 50 w/w%), is a glycoprotein which varies in its amino acids composition from that of the arabinogalactan-protein complex (GAGP -gum arabic glycoprotein).[99]