Non-starch polysaccharide compositions of rice grains with respect to rice variety and degree of milling

The chemical compositions of cell wall materials (CWM) in brown and milled rice were investigated using four rice varieties, Taichung Sen 10 (TCS10, indica), Tainung 67 (TNu67, japonica), Taichung Sen Waxy 1 (TCSW1, indica waxy), and Taichung Waxy 70 (TCW70, japonica waxy). The yield of CWM preparation, equivalent to total dietary fiber content, followed the order of TNu67 > TCS10 > the waxy cultivars. This order also held for the water solubility and pectic substance content of the CWM preparations and the compositional ratio of arabinose to xylose of all CWM samples. Comparatively, the nonwaxy CWM were rich in pectic substances and glucans; whereas the waxy CWM counterparts were dominant with hemicellulose plus cellulose and arabinoxylan-related polysaccharides. These results were more significant for the hot-water-soluble than insoluble parts and mainly dependent of rice variety rather than the degree of milling.     

Structure of pectic polysaccharides isolated from onion Allium cepa L. using a simulated gastric medium and their effect on intestinal absorption

The polysaccharide fraction extracted with simulated gastric juice from onion bulbs contained a mixture of galactan with short-length sugar chains, pectic polysaccharides and evident content of proteinaceous material. Galacturonan and rhamnogalacturonan were the main constituents of the linear regions of the sugar chains of the pectic polysaccharides. The ramified regions included rhamnogalacturonan-I. NMR data revealed that the side chains of the ramified region contained mainly 1,4-linked β-d-galactopyranose residues and lesser content of 1,3-linked β-d-galactopyranose and 1,5-linked α-l-arabinofuranose residues. Furthermore, the proteinaceous material was determined to be partly linked to the sugar chains.     

Role of pectic polysaccharides in structural integrity of apple cell wall material

Texture modulating properties of aqueous dispersions of apple cell wall material differed from those of tomato or kiwifruit, particularly under high shear. It was previously hypothesized that this may be due to the fact that the apple cell wall showed less in vivo solubilization of pectic polysaccharides during ripening compared to tomato or kiwifruit. However, in vitro solubilization of the pectic polysaccharide content of apple CWM by endo-polygalacturonase and/or extraction with 0.05 M sodium carbonate, did not affect the loss in wall integrity shown by tomato or kiwifruit CWMs under shear. In addition, the pectin-depleted residue after Na₂CO₃ extraction possessed better water retaining and viscosity generating properties than the original cell wall material. Following treatment of apple CWM with cellulase, the viscosity of suspensions decreased, emphasising the role that the cellulose–hemicellulose network plays in the water-retaining capacity of the cell wall. Residue from CWM after cellulase treatment consisted of ∼85% pectic polysaccharides. Surprisingly, the integrity of these “cellulose-free” walls was maintained after shear. It is concluded that differences in structural properties of the CWMs of apple compared to kiwifruit or tomato are not simply related to pectin solubilization but to a fundamental difference in the architecture of the apple cell wall.     

Glycosidic linkages of legume,grass and cereal straw cell walls before and after extensive degradation by rumen microorganisms

The technique of methylation analysis for the location of glycosidic linkages in cell wall polysaccharides was applied directly (after dry milling in liquid nitrogen) to whole wheat and barley straws, cell wall preparations from early- and late-cut perennial ryegrass and white clover, and their extensively degraded residues recovered from the rumen. The addition of an internal standard, methyl-β-D-allo-pyranose, to milled samples enabled the recovery of partially-methylated sugars to be quantified, and the recovery of parent sugars from methylated material to be compared with values obtained by direct estimation of monosaccharides by the alditol acetate method. Recovery of sugars from methylated samples was generally higher than that predicted by the alditol acetate method, particularly from digested residues. All four samples of Gramineae showed similar proportions of glycosidic linkages in which (1 →4)-linked xylose and glucose units accounted for more than 80% of total identified partially-methylated sugars. The proportions of glycosidic linkages found in digested residues of straws were essentially the same as those found in the parent material. In residues of the more digestible ryegrass there was a two- to three-fold increase in (1→4)-linked xylose units without branch points at the O-2/O-3 positions, the proportions of these branch points being substantially reduced. A corresponding reduction in the proportion of (1→2)-, (1→3)-and terminally-linked arabinose units was also found. The proportion of both (1→4)- and (1→3)-linked glucose units were also reduced in digested residues. These changes were greater in the early-cut than in the late-cut sample. White clover differed from the Gramineae in a number of respects. Galactose units predominantly in the form of (1→4)-, (1→6)- and terminally-linked units, were the major non-cellulosic sugars present. The proportion of all forms of galactose was reduced in digested residues, but (1→6)-linked units appeared more resistant to degradation than (1→4)-linked units. Like ryegrass, the proportion of xylose units increased in digested residues from clover, while the proportion of glucose decreased. The proportion of (1→4)-linked mannose units, initially present at levels ten times as great as in the Gramineae, was also substantially reduced.     

Cell Wall Composition of Olives

Cell walls of olives (Olea europaea L.), Hojiblanca and Manzanilla, were isolated and fractionated into polysaccharides, and compositions compared. Pectic and hemicellulosic fractions were purified by ion exchange and gel filtration chromatography, and neutral sugar and uronic acid composition determined. Differences occurred between cultivars and seasons: Manzanilla had higher pectic polysaccharides and lower xylans. Hojiblanca showed similar but lesser differences. Arabinans were the main neutral pectic polysaccharides with arabinose > 80%. Homogalacturonans and rhamnogalacturonans were > 50% of the acidic pectic fractions. Degree of esterification and molecular weights were related to extracting solvent. Xyloglucans and galactoglucomannans were neutral hemicelluloses with molecular weights ? 260 kD. Glucuronoarabinoxylans had higher molecular weights (up to 400 kD). Acidic xylans were important in the pulp.     

Modification of pectin polysaccharides during ripening of postharvest banana fruit

Pectin is one of the major components of the primary cellular walls and middle lamella in plant tissues. In this study, water-soluble pectin (WSP) and acid-soluble pectin (ASP) fractions were isolated from pulp tissues of banana fruit at various ripening stages. Their monosaccharide compositions, glycosyl linkages and molecular mass distributions were evaluated. As ripening progressed, fruit firmness decreased rapidly, which was associated with the increase in the WSP content and the decrease in the ASP content. Meanwhile, the molecular mass distributions of WSP and ASP fractions exhibited a downshift tendency, indicating the disassembly of pectin polysaccharides. Moreover, galactose and galacturonic acid as the major monosaccharide compositions of pectin polysaccharides increased in WSP fraction but decreased in ASP fraction during fruit softening. GC–MS analysis further revealed that pectin polysaccharide had a 1,4-linked galactan/galacturonan backbone with different types of branching and terminal linkages in WSP and ASP fractions. During banana fruit ripening, the amount of 1,4-linked Galp residues of ASP fraction decreased significantly whereas 1,3,6-linked Galp, 1,2-linked Manp and 4-linked Araf residues disappeared, which was related to depolymerization of pectin polysaccharides. Overall, the study indicated that the modifications in polysaccharide compositions and glycosyl linkages, reduced molecular mass distributions and enhanced depolymerization of pectin fraction during banana ripening were responsible for fruit softening.     

The structural studies of a polysaccharide purified from Oat Lao-Chao

Oat Lao-Chao contains bioactive components such as polysaccharides, of which immunomodulatory activity is recognised as the most important biological activity of polysaccharides. This paper studied optimisation of manufacturing Oat Lao-Chao, extraction of polysaccharide and removal of its protein, separation and purification of polysaccharide. The results showed that a water-soluble polysaccharide coded as LCPS-2 was isolated from Oat Lao-Chao. The polysaccharide was homogeneous and produced an asymmetrical peak obtained by high-performance gel permeation chromatography. Monosaccharide analysis revealed that LCPS-2 was containing arabinose, xylose, galactose, glucose and mannose in a ratio of 1.01: 0.72: 0.76: 0.28: 0.10. The GC-MS results of the derived alditol acetates from the permethylated LCPS-2 showed some separate peaks corresponding to (→6)- Galp,(→3,6)-Galp, terminal Ara, (→5)-Ara, (→1)-linked Xyl, (→3)-Xyl and (→6)-Glc units. NMR analysis and acid hydrolysis experiments indicated that the core structure features include a chain consisting of (1,3,6)-linked Galp, (1,4)-linked Galp, (1,5)-linked Ara residues.     

龙胆多糖的结构表征及其体外免疫活性

对龙胆多糖的结构和生物活性进行研究,采用甲基化分析多糖的链接方式。结果表明,龙胆多糖中存在(→1)末端和(1→5)-链接的呋喃阿拉伯糖基、(1→4)-链接的吡喃半乳糖基,同时也存在其他含量比较少的糖基和分支。龙胆多糖中糖醛酸是以(1→4)-链接的半乳糖醛酸方式存在,对龙胆多糖的生物活性起着重要的作用。龙胆多糖可以促进RAW264.7细胞增殖并产生NO,而且NO的产生是通过一氧化氮合成酶mRNA上调实现的,同时龙胆多糖可以上调细胞因子COX-2和TNF-α的mRNA表达水平。     

Cocoa bean carbohydrates: roasting-induced changes and polymer interactions

Roasting induced change to carbohydrates and cell wall polysaccharides was investigated in three varieties of cocoa beans. The concentrations of glucose and fructose decreased after roasting but levels of the non-reducing sugars, sucrose, raffinose, stachyose and verbascose, were not markedly affected. Approximately 10% of the arabinose content of the polysaccharides was degraded but, overall, the pectic and hemicellulosic polymers remained intact after roasting. The degree of esterification and acetylation of the pectic polysaccharides were unaffected by roasting. Roasting did promote an interaction between polysaccharides, proteins, polyphenolics and Maillard products. This led to the formation of insoluble complexes which co-purified with, and augmented, the levels of cell wall material isolated from roasted compared to unroasted beans. The implications of the results are discussed in relation to the role that “Klason lignin” plays in the formation of these chemical amalgams during roasting.     

A study on the composition of garlic skins and the structural features of the isolated pectic acid

An investigation of the composition of garlic skins showed the presence of proteins, lipids, lignin, mannitol, pectin and polysaccharides. Garlic skins are rich in pectin (27%), combined rhamnose (11.42%) and galactose (5.6%). Periodate oxidation studies of pectic acid showed the absence of 1,3-linked residues and branch points and indicated a linear galacturonan of 1,4-linked D-galacturonic acid. Chromatographic analyses were carried out on the hydrolysis products of pectic acid, which had been oxidised by periodate plus bromine, and also on those obtained after reduction of the periodate-oxidised pectic acid.     

Extraction of pectic polysaccharides from sugar‐beet cell walls

Previous methods of extracting pectin from sugar‐beet have used pulp as the starting material. As the temperature and pressure of the pulping process may modify the architecture of the cell wall, we have adapted a relatively non‐disruptive method to characterise cell wall material (CWM) isolated directly from the sugar‐beet. Cell walls from mature sugar‐beets (Beta vulgaris L Aztec) were sequentially extracted four times with imidazole and twice with sodium carbonate to produce six heterogeneous pectic polysaccharide extracts, and with KOH to produce a hemicellulosic extract which was predominantly xylans. Heterogeneity of the extracted pectins was indicated by differences in FTIR spectra, uronic acid content, % methyl esterification, % feruloylation, % acetylation, molecular weight distribution and neutral sugar composition. The highest proportion of feruloyl esters was found in polysaccharides solubilised by the second sodium carbonate extraction. Anion exchange chromatography of these polysaccharides gave three fractions, one of which contained most of the feruloyl ester. These results indicate that feruloyl esters are not randomly distributed among the different pectic polysaccharides in the sugar‐beet cell wall, and that esterification is likely to be dependent on the local sugar sequence or conformation. © 2000 Society of Chemical Industry     

Arabinan and arabinan-rich pectic polysaccharides from quinoa (Chenopodium quinoa) seeds: Structure and gastroprotective activity

After removal of starch, cell wall polysaccharides of seeds of quinoa were studied. They were extracted successively with water and with aq. 10% KOH. The extracted polysaccharides were fractionated and purified by freeze–thaw treatment and by sequential ultrafiltration through membranes. The purified fractions (PQW, K2-30EM, K1-10RM and K1-30RM) were analyzed by sugar composition, HPSEC, methylation and ¹³C NMR spectroscopy analysis. The results showed that PQW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions K2-30EM, K1-10RM and K1-30RM were related to rhamnogalacturonan type I with a branched arabinan and galactan side-chains. This arabinan has (1 → 5)-linked α-l-arabinofuranosyl units substituted exclusively in O-3. The main differences between these fractions were their molecular mass and content of Rha and GalA, which probably arise from an increase in their rhamnogalacturonan backbone. A pool of these polysaccharides (arabinan and arabinan-rich pectic polysaccharides) showed gastroprotective activity on ethanol-induced acute gastric lesions in rats.     

Pectin isolated from white cabbage--structure and complement-fixing activity

This study was done to investigate whether white cabbage contained polysaccharides with immunostimulatory activity using the complement-fixing test as an indicator. The main polysaccharide isolated was of pectin nature. Methanolysis and (13)C-NMR showed that the polymers consisted of highly esterified alpha-galactopyranoside (alpha-GalpA), significant amounts of alpha-arabinose furanoside (alpha-Araf), beta-Galp and lesser amounts of rhamnose in the pyranose form (Rhap) and xylose in the pyranose form (Xylp). Linkage analyses showed that the alpha-GalpA residues were mainly 1,4-linked with small amounts of 1,3,4-linkages. The alpha-Araf residues were mainly terminally (t)- and 1,5-linked, whereas beta-Galp was t-, 1,3-, 1,6-, and 1,3,6-linked. Positive Yariv reaction indicated polymers with arabinogalactan type 2 like structures. alpha-Rhap was mainly present as 1,2- and 1,2,4-linked residues and Xylp was t- and 1,4-linked. The molecular weight varied greatly and was from 10 to 150 kDa. Cabbage polymers had biological activity and this complement-fixing activity was greatly affected by hydrolytic removal of Araf from pectic side chains.     

Isolation,purification, and antioxidant activities of polysaccharides from Ziziphus Jujuba cv. Muzao

In the present study, crude polysaccharides from Ziziphus Jujuba cv. Muzao were isolated and purified using DEAE cellulose-52 and Sephadex G-100 size-exclusion chromatography; four fractions were collected, namely GZMP-1, GZMP-2, GZMP-3, and GZMP-4. The molecular weights of these four fractions were measured to be 111.2, 95.1, 84.2, and 571.4 kDa, respectively, using high-performance gel permeation chromatography. Gas chromatography analysis of the monosaccharide composition confirmed that GZMP-1 was composed of rhamnose, arabinose, glucose, and galactose. Rhamnose, arabinose, and galactose were the main components present in GZMP-2 and GZMP-3, whereas GZMP-4 was composed of only rhamnose and arabinose. Scanning electron microscopy showed relatively smooth surfaces for GZMP-1 and GZMP-4, whereas GZMP-2 and GZMP-3 had more folds on their surfaces. Fourier transform infrared spectroscopy analyses indicated that GZMP-1 and ZMP mainly had α-type glycosidic linkages. The in vitro antioxidant activities of the polysaccharides revealed that jujube polysaccharides exhibit remarkable antioxidant activity, and can scavenge DPPH radical and OH radical in a concentration-dependent manner. The results of this work suggest that polysaccharides from Z. Jujuba cv. Muzao have potential to be used as functional food and in the development of natural antioxidant drug carriers.     

Effect of dry‐salt processing on the textural properties and cell wall polysaccharides of cv. Thasos black olives

BACKGROUND: Thasos is an olive variety cultivated mainly in Greece used to produce ‘naturally black dry‐salted olives’. This process consists in placing the olives in disposed layers with coarse sodium chloride. The loss of water and other solutes gradually debitters and wrinkles the fruits. In this study, the effect of dry‐salt processing on the texture and cell wall polysaccharide composition was investigated. RESULTS: This type of processing affected primarily the mechanical properties of the olive flesh. In processed olives, this tissue was approximately 4.5 times stronger and also more deformable up to failure and stiffer than that from the raw olives. The dry‐salt processing had its strongest effect on pectic polysaccharides. This included the increment of solubilization of arabinose‐rich polymers in aqueous solutions, and thus their partial loss to the soak medium during dry‐salting. Contrarily, galacturonic acid‐rich polymers were further retained in the processed olives, probably by their stabilization within the cell walls by reduction of the electrostatic repulsion between the acidic groups of these polysaccharides due to sodium ions. CONCLUSION: The texture improvement of olive flesh by dry‐salt processing seems to be correlated with the reorganization of the galacturonic acid‐rich pectic polysaccharides into the cell wall of the fruit. Copyright © 2008 Society of Chemical Industry     

Degradation of carrot (Daucus carota) fibres with cell-wall polysaccharide-degrading enzymes

Carrot Daucus carota L fibres were degraded with two enzyme preparations, SP249 from Aspergillus aculeatus and Celluclast from Trichoderma reesei. The enzymic activities of these complexes indicate that SP249 was particularly active on pectic polymers, and Celluclast could degrade amorphous and crystalline cellulose. A combination of both preparations degraded carrot fibres with a synergistic effect and led to the solubilisation of 95% of the cell-wall polysaccharides. The kinetics of solubilisation of sugars and gel-permeation chromatography of the soluble products show that pectic polymers were rapidly solubilised and then, in a second stage, degraded mainly to monomers, whereas cellulose was more slowly hydrolysed to cellobiose and glucose. Part (67%) of the polysaccharides were saccharified, the residual soluble material being rhamnogalacturonans containing arabinose residues. Residual insoluble fibres (10% of initial weight) were not liquefied and were composed mainly of lignin, proteins and polymers of glucose, xylose and galacturonic acid.     

茉莉花渣中果胶型多糖的结构特征与免疫调节作用

为探究茉莉花渣中果胶型多糖的结构特征与免疫调节作用，本研究通过水提醇沉、蛋白脱除、阴离子交换柱层析和凝胶柱层析分离得到两种多糖JSP-3和JSP-4。通过相对重均分子量测定、单糖组成测定、部分酸水解液-质联用测定以及核磁共振波谱分析了两种多糖结构特征，最后以小鼠巨噬细胞RAW 264.7为模型，通过探究其对小鼠巨噬细胞的增殖率、吞噬率、ROS产生量以及NO、TNF-α、IL-6分泌量的影响来研究免疫调节作用。结果表明，JSP-3和JSP-4为两种均一多糖，相对重均分子量分别为15.48 kDa和 44.75 kDa，主要由半乳糖醛酸、鼠李糖、半乳糖和阿拉伯糖构成，存在不同比例的半乳糖醛酸聚糖结构域（JSP-3:32.87%±3.53%；JSP-4:68.64%±0.67%）与鼠李糖半乳糖醛酸聚糖结构域（JSP-3:61.12%±3.37%；JSP-4:28.28%±0.46%），说明两者均为果胶型多糖。与对照组相比，JSP-3和JSP-4在12.5~100 μg/mL的浓度范围内无细胞毒性，在一定浓度下能够通过促进小鼠巨噬细胞的吞噬作用，显著增加ROS产生量以及NO、TNF-α和IL-6的分泌量（P<0.05）。在相同浓度下，JSP-4比JSP-3能够刺激细胞分泌更多的NO、TNF-α和IL-6，说明JSP-4具有更强的免疫调节作用，这可能与其更高的半乳糖醛酸结构域比例和相对重均分子量有关。上述研究成果初步证明了茉莉花渣果胶型多糖的免疫调节作用，为其在免疫调节剂方面的应用提供了初步依据。     

Degradation characteristics of isolated and in situ cell wall lucerne pectic polysaccharides by mixed ruminal microbes

Two pectic polysaccharide fractions were isolated form lucerne (Medicago sativa L) leaves and used in fermentation experiments with mixed ruminal microbes. Both fractions were similar in chemical composition, containing galacturonic acid (52-58 mol%) and the neutral sugars arabinose (14-18 mol%), galactose (6-8 mol%) and rhamnose (8-12 mol%). Fermentation of both fractions was rapid and complete with a half-life of approximately 4 h. Production of total volatile fatty acids matched the degradation profile reaching a maximum level shortly after the rate of degradation began to decrease. The fermentation characteristics of citrus pectin and polygalacturonic acid were similar to those of the lucerne pectic fractions but galacturonic acid was much slower in its rate of degradation while soluble arabinogalactan from larchwood was virtually undegraded. Leaves of early bud stage lucerne and lower nodes and internodes of stems from full bloom lucerne were also fermented by mixed ruminal microbes. Pectic polysaccharides were rapidly and extensively degraded from both tissues. Initial rates were faster for leaves than for stems and the extent of pectic degradation was greater in leaves (8% residual) than in stems (17% residual). Selection of forage lines with increased pectic polysaccharides would provide greater amounts of rapidly available energy that could result in more efficient utilisation of the rapidly degraded protein in lucerne.     

An explorative study on the cell wall polysaccharides in the pulp and peel of dragon fruits (Hylocereus spp.)

The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.     

Physicochemical properties of cell wall materials from apple, kiwifruit and tomato

Cell wall materials (CWMs) were isolated from the fruit of ripe apple, kiwifruit and tomato using methods of isolation which maximised the water retaining capacity and viscosity generating properties of the CWMs. Aqueous suspensions of all three CWMs were able to form a gel-like matrix at a concentration of 1%. There was a dramatic enhancement in gel firmness of kiwifruit and tomato following a high shear treatment, but no such effect was apparent with apple CWM. Confocal microscopy showed that the shear-induced increase in viscosity was accompanied by fragmentation of the CWMs of kiwifruit and tomato which increased the available surface area for particle–particle and/or particle–solvent interaction. The viscosity of kiwifruit and tomato CWM dispersions was reduced in the presence of electrolytes indicating an important role for the double electrical layer in the gelling properties of the CWMs. The viscosifying properties of apple CWM were however independent of both shear and added electrolyte. This was attributed to the fact that CWM from apple resisted breakup under high shear. The greater connective integrity of the apple cell walls compared to that of kiwifruit and tomato is discussed in relation to differences in ripening induced changes to the pectic polysaccharides of the cell walls.