Chemical Methods for the Determination of Soluble and Insoluble Non-Starch Polysaccharides -Review (original) (raw)
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An Overview of Non Starch Polysaccharide
2015
Polysaccharides are macromolecules of monosaccharides linked by glycosidic bonds. Polysaccharides are widespread bi opolymers, which quantitatively represent the most important group o f nutrients in feed. These are major components of plant materials used in rations for monogastrics. Non-starch polysaccharides (NSP) contain s-glucans, cellulose, pectin and hemicellulose. NSP consist of both soluble and insoluble fractions. Soluble NSP of cereals such as wheat, barley and rye increases intestinal viscosity there by interfere w ith the digestive processes and exert strong negative effects on net utilisatio n of energy. NSP cannot be degraded by endogeneous enzymes and therefore reach the colon almost indigested. Insoluble NSP make up the bulk in the d iets. NSP are known to posses anti-nutritional properties by either encaps ulating nutrients and/or depressing overall nutrient digestibility through g astro-intestinal modifications.
International Journal of Food Properties, 2018
Cereals have captured global importance owing to the presence of bioactive moieties in cell wall. Numerous components have been considered but non-starch polysaccharides (NSP) of cereals cell wall are of prime concern. In this comprehensive review, the basic aim is to elaborate the functional and nutritional importance of cereals cell wall with special reference to NSP. Among bioactive components of cell wall, NSP, such as arabinoxylans, ßglucans, and arabinogalactans of wheat and barley, have gained much importance. Moreover, literature revealed that NSP have greater role as prebiotic, immunomodulator, antioxidant, anti-diabetic, and cardio-protector as well as major food applications.
Effect of extraction conditions on the solubility of non-starch polysaccharides of wheat and barley
Journal of Food Agriculture and Environment
The main physicochemical properties of non-starch polysaccharides (NSP) that are of nutritional significance include hydration properties, viscosity, cation exchange capacity and absorptive properties of organic compounds. Almost all water-soluble polysaccharides produce viscous solutions. The viscous properties of NSP depend on several factors, including their chemical composition, molecular size and composition of the extraction media. Wheat and barley contain substantial amounts of both soluble and insoluble NSP. The predominant water-soluble NSP in wheat is arabinoxylan (6-8%), while β-glucan is the predominant NSP in barley (7.6%). Experiments were conducted to investigate the influence of extraction conditions (pH and extraction time) on the viscosity of wheat and barley aqueous extracts. The extractions of soluble NSP were carried out in distilled water and in acidic buffer at three extraction times (15, 30 and 60 min) at 40°C. Water extract viscosity (WEV) and acid extract v...
Cereal Chemistry, 2010
Cereal Chem. 87(4):272-282 Noncellulosic polysaccharides from the cell walls of cereal grains are not digested by human small intestinal enzymes and so contribute to total dietary fiber intake. These polysaccharides are becoming recognized increasingly for their potential to lower the risk of serious diet-related conditions such as type II diabetes, cardiovascular disease, colorectal cancer, and diverticular disease. The effectiveness of noncellulosic cell wall polysaccharides in improving health outcomes is related to the fine structure and associated physicochemical properties. The two most nutritionally relevant wall polysaccharides of cereal grains are the arabinoxylans and the (1-3,1-4)-β-D-glucans. These polysaccharides have high molecular mass values but are nevertheless soluble in aqueous media, at least in part, where they adopt highly asymmetrical conformations and consequently form high viscosity solutions. Thus, arabinoxylans and (1-3,1-4)-β-D-glucans contribute to the soluble fiber component of human diets. The molecular size, solubility, and viscosity of the polysaccharides vary widely not only between different cereals but also within a single species. The variability in these properties reflects differences in the chemical structure of the polysaccharides, which in turn influences the beneficial effects of arabinoxylans and (1-3,1-4)-β-D-glucans in human diets. Here, we summarize information on the variability of fine structures of the arabinoxylans and (1-3,1-4)-β-D-glucans in common cereals and relate these to solubility, viscosity, and health benefits. The recent identification of genes involved in the biosynthesis of the (1-3,1-4)-β-D-glucans opens the way for the genetic improvement of cereal quality parameters that are important in human health.
Ultracentrifuge Methods for the Analysis of Polysaccharides, Glycoconjugates, and Lignins
Elsevier eBooks, 2015
Although like proteins, polysaccharides are synthesized by enzymes, unlike proteins there is no template. This means that they are polydisperse, do not generally have compact folded structures, and are often very large with greater nonideality behavior in solution. This chapter considers the relevant analytical ultracentrifuge methodology available for characterizing these and related carbohydrate-based systems and information this methodology supplies, in terms of sizes, shapes, and interactions using a comprehensive range of examples, including glycoconjugates and lignins. The relevance and potential of recent software developments such as SEDFIT-MSTAR, the Extended Fujita algorithm, and HYDFIT are considered.
2011
Abstract—Cereal grains contain various amounts of non-starch polysaccharides (NSP), which are composed predominantly of arabinoxylans (pentosans), s-glucans and cellulose. The detrimental effect of soluble NSP is mainly associated with the viscous nature of these polysaccharides and their physiological effects on the digestive medium. Experiments were conducted to investigate the influence of some extraction conditions on the viscosity of wheat and barley aqueous extracts. Water extract viscosities (WEV) appeared to be related to the particle size of the meals obtained after grinding. The study shows that viscosities of aqueous extracts of wheat and barley samples have maximum values at 0.5 mm size. The experiments carried out at different extraction temperatures revealed that the optimum temperature for extraction the soluble fraction of NSP is 40°C. At lower temperature (20°C) the extractability of NSP soluble fraction was lower, and at higher temperature (60°C) viscosity increa...
Planta, 2006
Plant cell wall polysaccharides vary in quantity and structure between different organs and during development. However, quantitative analysis of individual polysaccharides remains challenging, and relatively little is known about any such variation in polysaccharides in organs of the model plant Arabidopsis thaliana. We have analysed plant cell wall pectic polysaccharides using polysaccharide analysis by carbohydrate gel electrophoresis. By highly specific enzymatic digestion of a polysaccharide in a cell wall preparation, a unique fingerprint of short oligosaccharides was produced. These oligosaccharides gave quantitative and structural information on the original polysaccharide chain. We analysed enzyme-accessible polygalacturonan (PGA), linear b(1,4) galactan and linear a(1,5) arabinan in several organs of Arabidopsis: roots, young leaves, old leaves, lower and upper inflorescence stems, seeds and callus. We found that this PGA constitutes a high proportion of cell wall material (CWM), up to 15% depending on the organ. In all organs, between 60 and 80% of the PGA was highly esterified in a blockwise fashion, and surprisingly, dispersely esterified PGA was hardly detected. We found enzyme-accessible linear galactan and arabinan are both present as a minor polysaccharide in all the organs. The amount of galactan ranged from $0.04 to 0.25% of CWM, and linear arabinan constituted between 0.015 and 0.1%. Higher levels of galactan correlated with expanding tissues, supporting the hypothesis that this polysaccharide is involved in wall extension. We show by analysis of mur4 that the methods and results presented here also provide a basis for studies of pectic polysaccharides in Arabidopsis mutants.
Journal of Cereal Science, 2008
Isolated and purified endosperm cell walls (CW), used in this study, were derived from a Canadian malting barley variety, AC Metcalfe, grown in three different environments in Canada in 2003, and varying in grain protein and b-glucan contents, as well as in grain hardness. The CW were initially extracted with water at 45 C and subsequently digested with barley malt crude enzyme extract resulting in two fractions designated CW-WE45 and CW-MD, respectively. The remaining non-digested cell wall material (CW ND ) was further fractionated by sequential extraction with water at 95 C (CW ND -WE95), saturated barium hydroxide (CW ND -BaE), and 1 N sodium hydroxide (CW ND -NaE) at 25 C. Composition and molecular structure analyses were carried out for all fractions including the remaining cell wall residue (CW RES ). Extraction of CW with water followed by digestion with malt crude enzyme extract solubilized the majority of b-glucans (w55e70%) and glucomannans (w60e80%) but only a small portion of arabinoxylans (w20e30%) present in the intact CW. The CW-WE45 and CW ND -WE95 fractions consisted mostly of b-glucans exhibiting high average molecular weights (M w ) (2e3 Â 10 6 ), whereas the CW ND -BaE consisted mainly of arabinoxylans with M w about 1e1.5 Â 10 6 . The CW ND -NaE contained almost equal amounts of b-glucans and arabinoxylans and a small amount of glucomannans, whereas the CW RES contained approximately equal proportions of b-glucans, arabinoxylans and glucomannans. b-Glucans in CW ND -WE95, CW ND -NaE, and CW RES exhibited a higher ratio of 3-O-b-D-cellobiosyl-D-glucose to 3-O-b-D-cellotriosyl-D-glucose (DP3/DP4) compared to b-glucans in CW-WE45 and CW-MD. b-Glucans in CW ND -NaE showed the highest level of long cellulosic oligosaccharides with DP ! 5, whereas those in the CW RES had the highest DP3/DP4 ratio. The CW-MD was fractionated by ultrafiltration into high (CW-MD HMW ) and low-molecular weight (CW-MD LMW ) sub-fractions, with weight-average M w of w150e350 Â 10 3 and <10 Â 10 3 , respectively, as confirmed by size-exclusion chromatography. The monosaccharide composition of the sub-fractions indicated a more extended enzymic degradation of b-glucans and glucomannans than arabinoxylans. Some differences in composition and molecular structure of the cell wall constituents among the three barley samples were related to their solubility and enzymic digestibility.
Assignment
Polysaccharides are relatively complex carbohydrates and are the most abundant of organic compounds, constituting about half of the organic carbon on Earth. Polysaccharides are macromolecules made up of many monosaccharidesjoined together by glycosidic bonds, hence they are very large and oftenbranched. Polysaccharides differ not monosaccharides but also in the length of the chains and in the amount of chain branching. Depending on its chemical composition, a polysaccharide can be a homopolysaccharide, where all of the monosaccharides in the polysaccharideare of the same type, or a heteropolysaccharide, where more than one type of monosaccharide is present. Homopolysaccharides are often named for the sugar unit they contain, so glucose homopolysaccharides are called glucans, and mannose homopolysaccharides are mannans. Generally, polysaccharides are also called glycans, which differ in the type of glycosidic linkages, degree and type of branching, length of glucan chains, molecular rmass, and conformation of polymers. Glucans strongly contribute to specific polysaccharide characteristics such as solubility, rheology, and other physical characteristics. Polysaccharides have a general formula of Cx(H2O)y, where x is usually a large number between 200 and 2500. Considering that the repeating units in the polymer backbone are often 6-carbon monosaccharides, the general formula can also be represented as (C6H10O5)n, where n = 40 to 3000. The most common constituent of polysaccharides is D-glucose, but D-fructose, D-galactose, D-mannose, L-arabinose, and d-xylose are also found. Some monosaccharide derivatives found in polysaccharides include the amino sugars (D-glucosamine and D-galactosamine), as well as their derivatives (N-acetylneuraminic acid and N-acetylmuramic acid) and simple sugar acids (glucuronic and uronic acids). Derived compounds from polysaccharides include carboxymethylcellulose, butyrates, cellulose nitrates, hydroxyalkylcellulose,and methylcellulose from cellulose; acetate, adipates, phosphates,succinates, and carboxymethyl, hydroxylethyl, hydroxylpropyl, and cationic salts from starches; and carboxymethyl, hydroxylpropyl, and cationic salts from guar gum; as well as several other compounds. The largest functional group is the hydroxyls. A given sugar residue can form only one glycosidic linkage with a hydroxyl group of another molecule.Polysaccharides and oligosaccharides have reducing and nonreducing ends.The reducing end of an oligo-or polysaccharide is the one end not involved in a glycosidic linkage. The sugar units constituting all of the other ends are attached through glycosidic linkage (acetal) and therefore are nonreducing ends. In a polysaccharide, the hydroxyl groups may sometimes be methylated or converted to sulfate esters or ketals, formed with pyruvic acid. The ability to form branched structures distinguishes polysaccharides from proteins andnucleic acids, which occur only as linear polymers. Despite the variety of different monomer units and the kinds of linkages present, the conformational positions of carbohydrate chains are limited, unlike proteins. Polysaccharides are produced by renewable resources, including plants,animals, microorganisms, seeds, fruits, vegetables, plant exudates, seaweeds,and micro algae. Carbohydrates constitute about 75% of the