Chemical Composition and Structure of Pentosans (Turkish with English Abstract)

Yıl 2009, Cilt: 34 Sayı: 1, 37 - 42, 01.02.2009

Hülya Gül Halef Dizlek

Öz

Pentosans, which are the main non-starch polysaccharides of wheat kernel can be separated in to water-soluble and water-insoluble fractions. Arabinoxylans and arabinogalactans are the fundamental constituents of both. Arabinoxylans have a backbone of (1-4)-linked β-D-xylopyranosyl residues, which may be un-, mono-, or di-substituted with terminal α-L arabinofuranosyl residues. Arabinogalactans have a branch structure with β-D-galactopyranosyl residues linked through (1-3) and (1-6) glycosidic bonds and terminal α-L arabinofuranosyl residues. When compared with arabinoxylans, arabinogalactans have a higher ratio of galactose and lower ratio of xylose. Arabinose and xylose is the main constituent of water insoluble pentosans. Arabinoxylans form an average 60% of them. Arabinose to xylose ratio of water insoluble pentosans is higher than water soluble pentosans. Therefore they have higher branched structure, molecular weight and water binding capacity than water-extractable pentosans.

Anahtar Kelimeler

Non-Starch Polysaccharides, Water-Extractable Pentosans, Water-Unextractable Pentosans, Arabinoxylan, Arabinogalactan.  

Pentozanların Kimyasal Bileşimleri ve Yapıları

Öz

Buğday tanesinde bulunan başlıca nişasta dışı polisakkaritlerden olan pentozanlar; suda çözünen ve suda çözünmeyen pentozanlar olmak üzere iki grup altında incelenirler. Her ikisinin de yapısında arabinoksilan ve arabinogalaktan fraksiyonları bulunur. Arabinoksilanın temel yapısını birbirlerine β (1-4) glikozidik bağları ile bağlanmış anhidro-D-ksilopiranozil birimleri ile yan zincirlere tekli veya ikili olarak bağlanmış tek birimlik α-L arabinofuranozlar oluşturur. Arabinogalaktan, birbirlerine β-(1-3) ve β-(1-6) glikozidik bağları ile bağlanmış galaktopiranozil ünitelerinden oluşmuş dallı bir yapıya sahiptir. Sadece tek birimlik arabinoz üniteleri esas galaktoz ünitesine β- glikozidik olarak bağlanmıştır. Arabinoksilan ile karşılaştırıldığı zaman, arabinogalaktanın, galaktoz oranı yüksek, ksiloz oranı düşüktür. Suda çözünmeyen pentozanların da başlıca bileşenleri arabinoz ve ksilozdur ve bu pentozanların yaklaşık %60’ını arabinoksilanlar oluşturur. Suda çözünen pentozanlara göre, arabinozun ksiloza oranı daha yüksektir. Bu nedenle dallanma dereceleri, molekül ağırlıkları ve su bağlama kapasiteleri suda çözünen pentozanlara göre daha fazladır.

Anahtar Kelimeler

Nişasta Dışı Polisakkaritler, Suda Çözünen Pentozanlar, Suda Çözünmeyen Pentozanlar, Arabinoksilan, Arabinogalaktan.Nişasta Dışı Polisakkaritler, Suda Çözünen Pentozanlar, Suda Çözünmeyen Pentozanlar, Arabinoksilan, Arabinogalaktan.

Kaynakça

• Lineback DR, Rasper VF, 1988. Wheat carbohydrates. In Wheat: Chemistry and Technology, Y Pomeranz (ed), pp. 277-373, American Association of Cereal Chemists, Inc., USA.
• Yeh YF, Hoseney RC, Lineback R. 1980. Changes in wheat flour pentosans as a result of dough mixing and oxidation. Cereal Chem. 57 (2): 144-148.
• Izydorczyk MS, Biliaderis CG, Bushuk W. 1990. Oxidative gelation studies of water-soluble pentosans from wheat. J Cereal Sci, 11: 153-169.
• Rouau X, Moreau D. 1993. Modification of some physicochemical properties of wheat flour pentosans by an enzyme complex recommended for baking. Cereal Chem, 70 (6): 626-632.
• Izydorczyk MS, Biliaderis CG, Bushuk W. 1991. Comparison of the structure and composition of water-soluble pentosans from different wheat varieties. Cereal Chem, 68 (2): 139-144.
• Saulnier L, Peneau N.Thibault JF. 1995. Variability in grain extract viscosity and water-soluble arabinoxylan content in wheat. J Cereal Sci, 22: 259-264.
• Cleemput G, Booij C, Hessing M, Gruppen H, Delcour JA. 1997. Solubilisation and changes in molecular weight distribution of arabinoxylans and protein in wheat flours during bread-making, and the effects of endogenous arabinoxylan hydrolysing enzymes. J Cereal Sci, 26: 55-66.
• Hoseney RC. 1983. Principles of Cereal Science and Technology. American Association of Cereal Chemists, Inc., 327 s, USA.
• Westerlund E, Andersson R, Aman P, Theander O. 1990. Effects of baking on water-soluble non-starch polysaccharides in white bread fractions. J Cereal Sci, 12: 33-42.
• Izydorczyk MS, Biliaderis CG. 1992. Influence of structure on the physicochemical properties of wheat arabinoxylan. Carbohyd Polym 17: 237-247.
• Cleemput G, Roels SP, Oort MV, Grobet PJ, Delcour JA. 1993. Heterogeneity in the structure of water-soluble arabinoxylans in European wheat flours of variable bread-making quality. Cereal Chem, 70 (3): 324-329.
• Izydorczyk MS, Biliaderis CG. 1993. Structural heterogeneity of wheat endosperm arabinoxylans. Cereal Chem. 70 (6): 641-646.
• Andersson R, Westerlund E, Aman P. 1994. Natural variations in the contents of structural elements of water-extractable non-starch polysaccharides in white flour. J Cereal Sci, 19: 77-82.
• Dervilly PG, Rimsten L, Saulnier L, Andersson R, Aman P. 2001. Water-extractable arabinoxylan from pearled flours of wheat, barley, rye and triticale. evidence for the presence of ferulic acid dimers and their involment in gel formation. J Cereal Sci, 34: 207-214.
• Dervilly PG, Saulnier L, Roger P, Thibault JF. 2000. Isolation of homogeneous fractions from wheat watersoluble arabinoxylans. Influence of the structure on their macromolecular characteristics. J. Agric Food Chem, 48: 270-278.
• Izydorczyk MS, Biliaderis CG, Bushuk W. 1991. Physical properties of water-soluble pentosans from different wheat varieties. Cereal Chem, 68 (2): 145-150. 17. Hoffman RA, Roza M, Maat J, Kamerling JP, Vligenthart JFG. 1991. Structural characteristics of the cold-water soluble arabinoxylans from the white flour of the soft wheat variety kadet. Carbohyd Polym, 15: 415-430.
• Sancho AI, Bartolome B, Gomez-cordoves C., Williamson G, Faulds CB. 2001. Release of ferulic acid from cereal residues by barley enzymatic extracts. J Cereal Sci, 34: 173-179.
• Meuser F, Suckow P. 1986. Non starch polysaccharides. In: Chemistry and Physics of Baking, JMV. Frazier and T Galliard. (eds), pp. 42-61, The Royal Society of Chemistry.
• Fincher GB, Sawyer WH, Stone BA. 1974. Chemical and physical properties of an arabinogalactan-peptide from wheat endosperm. Biochem J, 139, 535-545.
• Strahm A, Amado R, Neukom H. 1981. Hydoxyproline-galactoside as a protein–polysaccharide linkage in a water soluble arabinogalctan-peptide from wheat endosperm. Phytochem, 20: 1061.
• Loosveld AMA. Delcour JA. 2000. The significance of arabinogalactan-peptide for wheat flour bread making. J Cereal Sci, 32: 147-157.
• Loosveld A, Maes C, Van Casteren WHM, Schols HA, Grobet PJ, Delcour JA. 1998. Structural variation and levels of water-extractable arabinogalactan-peptide in european wheat flours. Cereal Chem 75 (6): 815-819.
• Gruppen H, Marseille JP, Voragen AGJ, Hamer RJ. 1990. On the large scale isolation of water-insoluble cell wall material from wheat flour. Cereal Chem, 67 (5): 512-514.
• Gruppen H, Kormelink FJM, Voragen AGJ. 1993. Enzymic degradation of water-unextractable cell wall material and arabinoxylans from wheat flour. J Cereal Sci, 18: 129-143.
• Rouau X, Surget A. 1998. Evidence for the presence of a pentosanase inhibitor in wheat flours. J Cereal Sci, 28: 63-70.
• Courtin CM, Delcour JA. 2001. Relative activity of endoxylanases towards water-extractable and water-unextractable arabinoxylan. J Cereal Sci, 33: 301-312.
• Michniewicz J, Biliaderis CG, Bushuk W. 1990. Water-insoluble pentosans of wheat: composition and some physical properties., Cereal. Chem. 67 (5): 434-439.
• Eliasson AC. Larsson K. 1993. Cereals In Bread Making. Marcel Dekker, Inc., 376 s. USA.
• Michael ENA. 1990. Biochemistry of Food. Academic Press, Inc, 557 s. USA.