Composition and properties of pectin polysaccharides of St. John’s wort Hypericum Perforatum L.

Three fractions of acidic water-soluble polysaccharides (concentration of glucuronic acid 10?C65%) were obtained from the above-ground part of St. Johns wort Hypericum perforatum L. by serial extraction with water and 0.7% aqueous solution of ammonium oxalate. Enzymatic hydrolysis of these polysaccharides using endo-polygalacturonase indicates that their carbohydrate chains contain the units of galacturone formed by 1,4-??-linked residues of non-substituted D-galacturonic acid. The extracted polysaccharides have been purified by means of gel filtration. It has been shown that water-soluble polysaccharides obtained by extraction with water manly contain the residues of galactose, mannose, glucose, and arabinose (the concentration of glucuronic acid being 10?C27%) while the polysaccharide fraction extracted using 0.7% aqueous solution of ammonium oxalate is presented by pectin polysaccharides. Only the residues of galacturonic acid (55?C72%) have been identified among glucuronic acids in its composition using chromatography/mass spectrometry of trimethylsilyl derivatives. In addition, this fraction contains the residues of the neutral monosaccharides which are typical for pectins: arabinoses, galactoses, rhamnoses, and glucose; there are also minor concentrations of residues of xylose and mannose. IR spectra of pectin polysaccharides of St. John??s wort have absorption bands in the ranges 1740, 1640?C1620, 1236?C1200, and 1200?C1000 cm^?1 which are typical for pectins. It has been demonstrated that aqueous solutions of pectin polysaccharides of St. John??s wort (2 mg/mL) have pronounced antioxidant activity (44% of the activity of trolox taken for 100%).     

Studies on the intermolecular distribution of industrial pectins by means of preparative size exclusion chromatography

Three industrial high methoxyl pectins have been fractionated by size exclusion chromatography (SEC) on a preparative scale and the chemical composition, viscosity and light scattering behaviour of the fractions have been investigated. Chemical analysis revealed that the composition varies greatly from one SEC fraction to another. In all three pectin samples, the fractions of low molecular size contain most of the free neutral polysaccharides as well as some free pectin ‘hairy regions’. In addition, the lemon pectin samples contain some pectin molecules of large size which are rich in neutral sugars. Phenolic and proteinaceous compounds coelute with neutral sugar-rich fractions. However, in the apple pectin, phenolics and proteins occur predominantly in the fractions of low molecular size. Lemon pectin molecules, especially that of the lemon A sample, are prone to aggregation in the presence of calcium cations. The aggregate fraction can be disrupted by shear forces, heating or the presence of a chelating agent. The formation of such calcium-pectinate aggregates seems to be due to the presence of some molecules with low degrees of methoxylation. Light scattering measurements also suggest that even very narrow SEC fractions remain highly heterogeneous on the basis of their molecular weight, thus indicating large differences in molecular conformation.     

Changes in cell-wall polysaccharides from the mesocarp of grape berries during veraison

Softening of grape berries ( Vitis vinifera L. × V. labruscana cv. Kyoho) was evaluated by studying changes in composition and degradation of cell-wall polysaccharides. The grape berry softens at the beginning of the second growth cycle many weeks before harvest. The softening stage is called 'veraison' by viticulturists. On day 50 after full bloom, green hard berries (before veraison [BV]), softening berries (veraison [V]) and partly peel colored berries (C) were selected from the same clusters. In addition, mature berries (M) were collected on day 78 after full bloom. Mesocarp tissues at each stage were fractionated into hot water-soluble (WS), hot EDTA-soluble (pectin), alkali-soluble (hemicellulose) and residual (cellulose) fractions. Neutral and acidic sugar contents of WS and pectin fractions decreased only after the V stage, while the neutral sugar content of the hemicellulose fraction decreased from the BV to V stages. Cellulose content constantly decreased as the berry ripened, but the large decrease was found from the BV to V stages. Molecular masses of pectic and hemicellulosic polysaccharides decreased from the BV to V stages. Hemicellulosic xyloglucan was markedly depolymerized from the BV to V stages. The neutral and acidic sugar composition of each fraction changed little during the berry ripening. These data indicated that softening of berry during veraison involved the depolymerization of pectin and xyloglucan molecules and decrease in the amounts of hemicellulose and cellulose.     

Predicting In Vitro Rumen VFA Production Using CNCPS Carbohydrate Fractions with Multiple Linear Models and Artificial Neural Networks

The objectives of this trial were to develop multiple linear regression (MLR) models and three-layer Levenberg-Marquardt back propagation (BP3) neural network models using the Cornell Net Carbohydrate and Protein System (CNCPS) carbohydrate fractions as dietary variables for predicting in vitro rumen volatile fatty acid (VFA) production and further compare MLR and BP3 models. Two datasets were established for the trial, of which the first dataset containing 45 feed mixtures with concentrate/roughage ratios of 10∶90, 20∶80, 30∶70, 40∶60, and 50∶50 were used for establishing the models and the second dataset containing 10 feed mixtures with the same concentrate/roughage ratios with the first dataset were used for testing the models. The VFA production of feed samples was determined using an in vitro incubation technique. The CNCPS carbohydrate fractions (g), i.e. CA (sugars), CB₁ (starch and pectin), CB₂ (available cell wall) of feed samples were calculated based on chemical analysis. The performance of MLR models and BP3 models were compared using a paired t-test, the determination coefficient (R²) and the root mean square prediction error (RMSPE) between observed and predicted values. Statistical analysis indicated that VFA production (mmol) was significantly correlated with CNCPS carbohydrate fractions (g) CA, CB₁, and CB₂ in a multiple linear pattern. Compared with MLR models, BP3 models were more accurate in predicting acetate, propionate, and total VFA production while similar in predicting butyrate production. The trial indicated that both MLR and BP3 models were suitable for predicting in vitro rumen VFA production of feed mixtures using CNCPS carbohydrate fractions CA, CB₁, and CB₂ as input dietary variables while BP3 models showed greater accuracy for prediction.     

Pectin polysaccharides of rowan Sorbus aucuparia L.

Water-soluble polysaccharide fractions were extracted from the fruit of rowan Sorbus aucuparia L. by water and 0.7% ammonium oxalate water solution. The total yield was 4.2%. It is demonstrated that these fractions are pectin polysaccharides, and their carbon chains are primarily composed of galactunoric acid residue (up to 68%), arabinose and galactose. Sephacryl S-500 gelfiltration of rowan fruit pectin polysaccharides proved their relative homogeneity pertaining to their molecular weights, whereas endo-polygalacturonase enzymatic hydrolysis gives evidence of the presence of extended galacturonan (rhamnogalacturonan) ranges in their carbohydrate chains. Methylation of rowan pectin polysaccharides shows that their carbohydrate pendants are formed by 1,5-linked arabinofuranose residue, 1,4-linked glucopyranose residue, 1,6-linked galactopyranose residue, 1,3,6-linked mannopyranose residue and 1,3,6-linked galactopyranose residue. Glucopyranose residue is identified at non reducible ends of these pendants. It was demonstrated that antioxidant activity of water solutions of pectin polysaccharides extracted from rowan S. aucuparia L. (0.5 mg/mL) is 37?C53% of trolox activity, which is 100%.     

Hypoglycaemic effect of defatted seeds and water soluble fibre from the seeds of Syzygium cumini (Linn.) skeels in alloxan diabetic rats

The effect of feeding orally along with diet of different fractions obtained from the seeds of S. cumini was tried on fasting blood glucose and glucose tolerance in normal and alloxan diabetic rats. The quantitative determination showed that S. cumini seeds contained 40% of water soluble gummy fibre and 15% of water insoluble neutral detergent fibre (NDF). This study demonstrated that feeding for 21 days of the diets containing 15% powdered unextracted (intact) seeds containing water soluble gummy fibre, 15% powdered defatted seeds from which lipid and saponins were removed only and 6% water soluble gummy fibre isolated from S. cumini seeds significantly lowered blood glucose levels and improved oral glucose tolerance whereas feeding of the diets containing 15% powdered degummed S. cumini seeds from which water soluble gummy fibre was removed but which contained neutral detergent fibre (NDF) and 2.25% water insoluble neutral detergent fibre (NDF) isolated from S. cumini seeds neither lowered blood glucose levels nor improved oral glucose tolerance in both normal and diabetic rats. These observations indicate that the hypoglycaemic effect of S. cumini seeds was due to water soluble gummy fibre and also that water insoluble neutral detergent fibre (NDF) and other constituents of the seeds had no significant hypoglycaemic effects.     

Characterisation of secreted polysaccharides and (glyco)proteins from suspension cultures of Pyrus communis

High molecular weight material recovered from the culture filtrate of cell suspension cultured Pyrus communis was composed of 81% carbohydrate, 13% protein and 5% inorganic material. This material was separated into three fractions (one neutral (Fraction A) and two acidic (Fractions B and C)), by anion-exchange chromatography on DEAE-Sepharose CL-6B using a gradient of imidazole-HCl at pH 7.0. The monosaccharide and linkage composition of each fraction was determined after carboxyl reduction of uronic acid residues. From the combined results of the carbohydrate analyses, we conclude that the high molecular weight extracellular material consists of three major and two minor polysaccharides: a (fucogalacto)xyloglucan (36%) in the unbound neutral Fraction A; a type II arabinogalactan (as an arabinogalactan-protein, 29%) and an acidic (glucurono)arabinoxylan (2%) in Fraction B; and a galacturonan (33%) and a trace of heteromannan in Fraction C. The main amino acids in the proteins were Glx, Thr, Ser, Hyp/Pro and Gly. Further separation of Fraction B by solvent partition, SDS-PAGE and analysis by LC-MS/MS identified the major proteins as two chitanases, two thaumatin-like proteins, a beta-1,3-glucanase, an extracellular dermal glycoprotein and a pathogenesis-related protein.     

Standardization of procedures for nitrogen fractionation of ruminant feeds

The Cornell Net Carbohydrate Protein Model (Chalupa et al., 1991; Sniffen et al., 1992) has developed the need for uniform procedures to partition feed nitrogen into A, B, and C fractions (Pichard and Van Soest, 1977). While carbohydrate fractions are relatively standardized (based on NDF, ADF with corrections for ash, protein, and lignin), the fractionation of plant nitrogen has been open to considerable variation in procedures. This has led to non-uniformity among reported values for nitrogen fractions. This paper recommends reliable procedures for nonprotein nitrogen (NPN) and buffer-soluble protein. These procedures have been examined for reproducibility and relevance to biological expectations. Procedures for acid-detergent insoluble nitrogen (ADIN), and neutral-detergent insoluble nitrogen (NDIN) are also included as they are required for the model. Some alternatives in certain procedures are offered.     

Study of supramolecular structures released from the cell wall of Candida albicans by ethylenediamine treatment

Candida albicans cell wall components were analyzed by ethylenediamine (EDA) treatment. Based on their different solubility properties, the cell wall components produced three fractions (A, B, and C). Fractions B (EDA-soluble, water-insoluble) and C (EDA-insoluble) contained glucan, chitin, and protein in different proportions. After zymolyase (mainly a β-glucanase complex) or chitinase treatment of fractions B and C, more polysaccharides and proteins were solubilized by a second EDA treatment, suggesting that the solubility of the polymers in EDA depends on the degree of polymer interactions. Western blot analysis using two monoclonal antibodies (1B12 and 4C12) revealed electrophoretic patterns that were similar in mycelial and yeast morphologies, except that in material obtained from mycelial walls, an additional band was detected with MAb 1B12. Fluorescence microscopy of cell wall fractions treated with FITC-labeled Con-A, Calcofluor white, and FITC-labeled agglutinin showed that glucan and mannoproteins are uniformly distributed in fractions B and C, while chitin is restricted to distinct patches. Transmission electron microscopy demonstrated that fraction C maintained the original shape of the cells, with an irregular thickness generally wider than the walls. When fraction C was treated with chitinase, the morphology was still present and was maintained by an external glucan layer, with an internal expanded fibrillar material covering the entire cellular lumen. Degradation of the glucan skeleton of fraction C with zymolyase resulted in the loss of the morphology. Received: 1 April 1996 / Accepted: 2 September 1996     

Identification of lucerne stem cell wall traits related to in vitro neutral detergent fibre digestibility

Genetic improvement of forage digestibility, especially utilizing marker assisted selection and recombinant DNA techniques, requires identification of specific biochemical traits and associated genes that impact digestibility. We undertook a study to identify cell wall (CW) traits of lucerne (Medicago sativa L.) stems that were consistently and strongly correlated with in vitro neutral detergent fibre (NDF) digestibility, a measurement that has been shown to correlate with animal performance. Spring and summer harvested lucerne stem material, for 2 years, from 24 individual plants in each of two germplasm sources were analyzed for 16 and 96 h in vitro NDF digestibility, and cell wall concentration and composition (monosaccharide constituents of cellulose, hemicellulose, and pectin; and Klason lignin (KL)) by the Uppsala dietary fibre method using near-infrared reflectance spectroscopy (NIRS). Pearson correlation coefficients were calculated for the relationships among these cell wall traits and with in vitro NDF digestibility. Concentrations of the pectin monosaccharide components were all negatively correlated (r=−0.73 to −0.94) with total cell wall concentration. In contrast, the three most abundant cell wall components glucose (Glc), xylose (Xyl) and Klason lignin were not correlated, or only weakly positively correlated (r<0.35), with cell wall concentration. Cell wall concentration was consistently negatively correlated (r=−0.60 to −0.94) with both 16 and 96 h in vitro NDF digestibility. In contrast, Klason lignin concentration was only marginally correlated (r<0.30) with 16 h in vitro NDF digestibility, but strongly negatively correlated (r=−0.71 to −0.74) with 96 h in vitro NDF digestibility. This is consistent with previous reports which show that lignin affects potential extent of digestion, but not rate. Cell wall glucose and xylose concentrations were inconsistently correlated with fibre digestibility. The monosaccharide components of pectin were consistently positively correlated (r=0.54–0.90) with in vitro NDF digestibility, except for 96 h in vitro NDF digestibility of spring harvested stems. Growth environment (year) and germplasm source had only minor impacts on the preceding correlation patterns, whereas spring versus summer harvests accounted for the inconsistencies observed among correlations for cell wall traits. The results of this study indicate that genetic improvement of fibre digestibility of lucerne stems should target genes that reduce total cell wall concentration, perhaps by reducing the rate of xylem tissue deposition during maturation, and reduce Klason lignin and increase pectin concentrations in the cell wall to improve potential extent and rate of fibre digestibility, respectively.     

The structure, function, and biosynthesis of plant cell wall pectic polysaccharides

Plant cell walls consist of carbohydrate, protein, and aromatic compounds and are essential to the proper growth and development of plants. The carbohydrate components make up ∼90% of the primary wall, and are critical to wall function. There is a diversity of polysaccharides that make up the wall and that are classified as one of three types: cellulose, hemicellulose, or pectin. The pectins, which are most abundant in the plant primary cell walls and the middle lamellae, are a class of molecules defined by the presence of galacturonic acid. The pectic polysaccharides include the galacturonans (homogalacturonan, substituted galacturonans, and RG-II) and rhamnogalacturonan-I. Galacturonans have a backbone that consists of α-1,4-linked galacturonic acid. The identification of glycosyltransferases involved in pectin synthesis is essential to the study of cell wall function in plant growth and development and for maximizing the value and use of plant polysaccharides in industry and human health. A detailed synopsis of the existing literature on pectin structure, function, and biosynthesis is presented.     

A comparative study of the apparent total tract digestibility of carbohydrates in Icelandic and Danish warmblood horses fed two different haylages and a concentrate consisting of sugar beet pulp and black oats

Four Icelandic (ICE) and four Danish Warmblood (DW) horses were used in a crossover study with two treatments to investigate the effect of breed and the effect of stage of maturity of haylage on the apparent total tract digestibility (ATTD) of a diet consisting of sugar beet pulp, black oats and haylage early or late cut. Fibre was analysed as crude fibre (CF), acid detergent fibre (ADF), neutral detergent fibre (NDF) and dietary fibre (DF = non-starch polysaccharides (NSP) plus lignin). In haylage all analysed fibre fractions increased with advancing stage of maturity, with the cell wall components cellulose, non-cellulosic residue, xylose and lignin causing this increase. Crude protein (CP) and sugars decreased with advancing stage of maturity. Feeding early cut haylage resulted in a significantly (p < 0.05) higher ATTD of dry matter (DM), organic matter (OM), energy, NDF, total NSP, DF and CP compared to feeding late cut haylage. There was a significantly (p < 0.05) higher ATTD of CF, DF and starch in ICE than in DW. Diet affected several faecal parameters with a significantly (p < 0.05) lower pH in faeces when horses were fed the early cut haylage. Concentrations of total short-chain fatty acids were significantly (p < 0.05) higher in faeces from horses fed early cut haylage, reflecting the higher fermentability (higher ATTD) of this diet. There was no marked effect of breed on faecal parameters. The DF analysis method gave the most appropriate differentiation of the fibre fractions and their digestibility, compared to the traditional CF, ADF and NDF analyses. A major advantage of the DF analysis is the capacity of recovering soluble fibres. The results suggested that ICE had higher ATTD of DF than DW, and this was caused by a tendency for a higher ATTD of cellulose, but further studies are required to verify that in general.     

Bioactive polysaccharides from the stems of the Thai medicinal plant Acanthus ebracteatus: their chemical and physical features

Crude water-soluble polysaccharides were isolated from Acanthus ebracteatus by hot water extraction followed by ethanol precipitation after pre-treatment with 80% ethanol. The crude polysaccharides were separated into neutral and acidic polysaccharides by anion-exchange chromatography. The neutral polysaccharide (A1001) was rich in galactose, 3-O-methylgalactose and arabinose, whereas the acidic polysaccharide (A1002) consisted mainly of galacturonic acid along with rhamnose, arabinose and galactose as minor components indicating a pectin-type polysaccharide with rhamnogalacturonan type I (RG-1) backbone. 3-O-Methylgalactose is also present in the acidic fraction. Both neutral and acidic fractions showed potent effects on the complement system using pectic polysaccharide PM II from Plantago major as a positive control. A small amount of 3-O-methylgalactose present in the pectin seemed to be of importance for activity enhancement in addition to the amount of neutral sugar side chains attached to RG-1. The relationship between chemical structure and effect on the complement system of the isolated polysaccharides is considered in the light of these data. The presence of the rare monosaccharide 3-O-methylgalactose may indicate that this can be used as a chemotaxonomic marker. The traditional way of using this plant as a medical remedy appears to have a scientific basis.     

Modifications of cell wall polysaccharides during auxin-induced growth in azuki bean epicotyl segments

Changes in sugar compositions and the distribution pattern ofthe molecular weight of cell wall polysaccharides during indole-3-aceticacid (IAA)-induced cell elongation were investigated. Differentialextraction of the cell wall and gel permeation chroma-tographyof wall polysaccharides indicated that galactans, polyuronides,xylans, glucans and cellulose were present in the azuki beanepicotyl cell wall. When segments were incubated in the absence of sucrose, IAAenhanced the degradation of galactans in both the pectin andhemicellulose fractions, whereas to some extent it enhancedthe polymerization of xylans and glucans in the hemicellulosefraction and an increase in the amounts of polyuronides in thepectin fraction and of -cellulose. In the presence of 50 mMsucrose, IAA caused large increases in the amounts of all thewall polysaccharides, and enhanced the polymerization of galactans,xylans and glucans in the hemicellulose fraction. These results and an important role of galactan turnover incell wall extension are discussed. (Received December 11, 1979; )     

Estimate of chitin in raw whole insects

Insects contain significant amounts of fiber as measured by crude fiber, acid detergent fiber (ADF) or neutral detergent fiber (NDF). It has always been assumed that the fiber in insects represents chitin based on the structural similarity between cellulose and chitin and the fact that the ADF fraction from insects contains nitrogen. In this study, a number of insect species that are raised commercially as food for insectivores were analyzed for moisture, crude protein (nitrogen × 6.25), fat, ash, NDF, ADF, and amino acids. Additionally, the ADF fraction was analyzed for nitrogen and amino acids to determine if proteins might be present in the ADF fraction. The ADF fraction contained a significant amount of amino acids accounting for 9.3–32.7% of the ADF (by weight). The presence of amino acids in the ADF fraction means that using ADF to estimate insect chitin results in an overestimation of insect chitin content. Using ADF adjusted for its amino acid content, the estimated chitin content of these insect species ranged from 2.7–49.8 mg/kg (as is) and 11.6–137.2 mg/kg (dry matter basis). Additionally, these data suggest that for the species measured here the amount of chitin nitrogen is quite small (as a % of total nitrogen) and that crude protein (nitrogen × 6.25) provides a reasonable estimate of the true protein for most species of insects. Zoo Biol 0:1–11, 2007. © 2007 Wiley‐Liss, Inc.     

Chemical and biochemical variation in animal manure solids separated using different commercial separation technologies

Chemical and biochemical properties were investigated in 47 solids collected from commercial solids separation plants separating liquid manure into a nutrient-rich solid fraction and a nutrient-poor liquid fraction. The samples originated from five different types of separation technologies, separating primarily swine manure and anaerobically digested manure. The largest variations in measured chemical and biochemical characteristics between samples from the five different separation technologies were found for ash, total P, total C, DM and C distribution in the biochemical fractions (neutral detergent solubles (NDS), hemicellulose, cellulose and lignin). Principal component analysis (PCA) of the data obtained showed that the chemical and biochemical characteristics of the solids were dependent on the type of technology used for separation.     

An alternative oven method combined with different detergent strengths in the analysis of neutral detergent fibre

Two methods for preparing neutral detergent fibre (NDF) – the standard method of Van Soest, P.J., Robertson, G.B., Lewis, B.A., `Symposium: Carbohydrate methodology, metabolism, and nutritional implications in dairy cattle.' J. Dairy Sci. 74 3583–3597 (1991), and an alternative 16 h oven method at 90°C. Neutral detergent solution (100%) was compared with solutions diluted to 50, 25 and 0% of normal strength. Sodium sulfite and a heat-stable amylase were used in all treatments. Forty-four samples consisting of 11 dried and ensiled forages, three straws, nine starchy concentrates, 10 high-protein concentrate feeds, three samples of tropical browse leaves and eight manures from both ruminants and non-ruminants were used. The 0% treatment was the only treatment giving significantly higher NDF values compared to the others (p<0.05). Sensitivity to detergent strength seemed to be sample-specific in the high protein group as meat meal and maize gluten had higher NDF values at reduced detergent strengths. We recommend using the oven method and a detergent strength of 25% of the current standard in combination with sodium sulfite for low protein feeds. For starchy feeds a heat-stable amylase should be used and high lipid samples should be acetone-extracted before isolating NDF. For high protein feed samples only the standard method can yet be recommended. The oven method is labour-saving and more convenient and arguments for reduced detergent strength suggest lower cost and reduced waste water pollution.     

Release of Small Polyuronides from Nitella Cell Walls during Ionic Exchange

Mono-divalent ion exchange in isolated cell walls of Nitella flexilis (L.) Ag. induces a marked loss of wall polymers and a decrease in the wall cationic exchange capacity. These data correlate with the replacement in the walls of adsorbed Mn²⁺ by Na⁺ ions. Boiling wall samples in methanol for 1 h or keeping the ionic solutions chilled to 4°C does not inhibit the cell wall polymer leakage but modifies the kinetics both of the ionic exchange and of the released polymers. These data are more compatible with physical rather than enzymic induced processes. The extracted polymers in the successively renewed NaCl solutions initially belong to the wall protein and pectin fractions and mainly to pectic fractions subsequently. Determination of the average degree of polymerization shows that the average molecular size of the lost acidic polysaccharides increases with extraction time up an average polymerization degree of 25. Enzyme-linked immunosorbent assay inhibition tests show the presence of homopolymer blocks equal to or higher than 10 in the released polymer fragments. Compositional analysis of released polysaccharides suggests that the pectin lost by action of monovalent ions was largely composed of rhamnogalacturonans whose acidic residue fraction is approximately 60% in association with galactose chains. Small quantities of glucuronylated xylans are also found.     

Alkaline extractability of pectic arabinan and galactan and their mobility in sugar beet and potato cell walls

The organisation of sugar beet and potato cell walls was studied using alkaline extractions following a response surface methodology, simultaneously with solid-state ¹³C NMR spectroscopy. The influence of two extraction parameters: NaOH concentration (0.05, 0.275, 0.5 M) and temperature (40, 65, 90 °C) on the composition (neutral and acidic sugars) of the residues recovered was established. Treatments of increasing harshness progressively washed off non-cellulosic polysaccharides from the cell walls. Alkaline treatments applied to sugar beet cell wall material (SB-CWM) revealed the presence of diverse pectin populations. The existence of distinct pectin populations in potato cell wall material (P-CWM) was less outstanding. Solid-state ¹³C NMR applied to SB-CWM and P-CWM and residues after treatment by 0.275 M NaOH at 65 °C revealed two fractions of pectic arabinan and galactan side chains. One fraction was highly mobile, whereas the other one displayed restricted mobility.     

Distribution of C and N in soluble fractionations for characterizing the respective biodegradation of sludge and bulking agents

This study utilized C and N distribution in different soluble fractionations instead of the routine C/N ratio to characterize the respective biodegradation of sludge and bulking agents in bio-drying or composting. For sludge, C was mainly distributed (31.8%) in the neutral detergent soluble and water insoluble fraction (SOL), whereas it was mainly distributed in the cellulose-like fraction (CEL) for straw (39.5%) and sawdust (45.8%). A large proportion of N was in the 35 °C water-soluble fraction (W35 °C) for sludge (34.0%) and straw (52.5%), while for sawdust it was in the lignin-like fraction (LIG; 49.4%). For sludge, the C and N loss were mainly contributed by W35 °C (36.9% and 52.4%). The other fractions also contributed a lot. For straw, 22.4% of C and 89.8% of N lose in W35 °C. The hemicellulose-like (HEM) and CEL fraction also gave a large contribution to C loss (28.5% and 40.1%), while contributing little to N loss.