Chemical composition and in-vitro degradability of major chemical constituents of red clover harvested at different stages of maturity

The contents of extractives, starch, crude protein, non-starch polysaccharides and Klason lignin were determined in red clover harvested at six different stages of maturity. Chemical analysis of residues after incubation with rumen liquor in vitro revealed that the degradability of starch was 100% and of crude protein about 80% at all harvest times. The degradability of non-starch polysaccharides decreased from 76 to 51% during maturation and no degradation of Klason lignin was noticed. At all harvest times xylose was the least degraded non-starch polysaccharide residue followed by glucose and rhamnose. During maturation the greatest decrease in in-vitro degradability was noticed for the xylose residues followed by the glucose and the mannose residues.     

Changes during growth in anatomical and chemical composition and in-vitro degradability of lucerne

Lucerne (alfalfa) was harvested at different stages of maturity and the plants classified according to a phenological scale. The main class was separated into anatomical parts and analysed for content of extractives and crude protein and in-vitro degradability. Whole crop samples were also analysed for polysaccharide residues, Klason lignin and in-vitro degradability of crude protein and polysaccharide residues. The composition of the plant changed during maturation with an increase of the stem fraction from 18.5% to 50.7% of dry matter and a corresponding decrease in the leaf fraction from 72.9% to 18.4% of dry matter. The leaf fraction changed least in content of extractives and crude protein and in-vitro degradability while in the stems all these paramaters decreased radically. Chemical analysis of residues after incubation with rumen liquor in vitro of whole crop samples revealed that the degradability of crude protein declined from about 90% to about 80% and of non-starch polysaccharides from about 90% to about 60% during maturation. Xylose was the least degradable polysaccharide residue at all harvests. Xylose residues also showed the greatest decrease in degradability during growth. A comparison showed that stage of development and harvest date were of practically equal value as predictor of crude protein content in lucerne.     

Changes in cell-wall composition and degradability of sorghum during growth and maturation

Samples of sorghum (Sorghum bicolor Moench × Sorghum sudanense Stapf, cv ‘P 988’) were harvested at five growth stages. Quantitative methylation and acetalation–methylation methods were used to examine changes during growth of cell-wall polysaccharides, their association with phenolic compounds and the effects of changes on rumen degradability. Cellulose degradability, as measured by a nylon-bag method, decreased from 82·5% at the youngest stage to 36·5% at the milk-ripe stage, at a greater rate of change than degradability of dry matter. Among the monosaccharides contributing to cell-wall polysaccharides, the degradabilities of arabinose and uronic acid residues were consistently higher than those of xylose and glucose, the main components of structural carbohydrates. Recovery of parent neutral sugars from cell wall polysaccharides, calculated as the sum of partially methylated alditols, was in good agreement with the values obtained by direct estimation of individual sugars as their alditol acetate derivatives. Total non-starch polysaccharide content increased from 31·1% to 45·1% between the first two growth states, with little change evident thereafter. The relative proportion of individual to total sugars remained consistent throughout growth. The values for arabinose, xylose and glucose residues accounted for 4·9%, 27·9% and 63·0% of total neutral sugars, respectively. The pattern of glycosidic linkages detected could be mainly ascribed to the presence of (1–4)-β-D -glucans (cellulose), arabinoxylan, (1–3)(1–4)-β-D -glucans, (1–4)-β-D -galactan, (1–3)(1–6)-β-D -galactan, rhamnogalacturonan and, possibly, xyloglucan. The cellulose content of the five sorghums was, in order of growth, 14·3%, 21·8%. 22·3%, 21·2% and 22·0% of dry matter. The ratio of the mixed-linked g1ucan:cellulose decreased during growth. Arabinoxylan, the predominant hemicellulosic polysaccharide, was estimated to comprise about 33% of total neutral sugars consistently for all sorghum samples. Arabinose, found largely as terminal residues in the cell walls, carried various amounts of alkali-labile substituents, particularly at position 0–5, depending on the growth stage of sorghum. The extent of 0–5 substitution was closely correlated with both the lignin content (total phenolics minus phenolic acids, r = 0·903) and with cellulose degradability (r = 0·915).     

桑黄菌丝体多糖的分离纯化及理化性质分析

研究桑黄粗多糖的分离和纯化工艺,并对多糖组分进行理化性质分析。结果表明：经DEAE-52纤维素离子交换层析和Sephadex G-100凝胶过滤层析得到两个组分P-47000和P-8700;经高效液相色谱分析证明,两组分均为纯品,且不含蛋白质、核酸,为非淀粉类多糖,分子质量分别为4.74×104D和8.71×103D,均由鼠李糖、阿拉伯糖、木糖、葡萄糖、半乳糖组成,P-47000中各单糖物质的量比为3.47:1.99:1:63.27:13.44,P-8700中各单糖物质的量比为10.46:1:1.03:182.75:30.94。     

Endogenous rice endosperm hemicellulose slows in vitro starch digestibility

Hemicellulose, the primary non-starch polysaccharide originating from cell walls of rice endosperm, greatly influences the digestibility of starch in food matrix. Three rice varieties differing in total dietary fibre content were treated with hemicellulose and in vitro starch digestion with α-amylase was conducted. Removing the hemicellulase significantly promoted starch digestion, and the magnitude of the impact was dependent on rice variety. The impact was more pronounced in variety cw high in apparent amylose and total dietary fibre content, while was negligible on the japonica rice Nipponbare. Endogenous hemicellulose slowed in vitro starch digestibility in rice by interacting with amylose and amylopectin, particularly with the long chain amylopectins, inherent existing and during the cooking process. Non-starch polysaccharides, including hemicellulose, can be tailored in rice to modify the digestible carbohydrate content; however, more research is required to fully understand the interactions between non-starch polysaccharides and starch and their influences on grain quality.     

Impact of lignin composition on cell‐wall degradability in an Arabidopsis mutant

An Arabidopsis mutant that does not deposit syringyl‐type lignin was used to test the hypothesis that lignin composition impacts cell‐wall degradability. Two lines of the ferulate‐5‐hydroxylase‐deficient fah1 mutant and the wild‐type control line were grown in the greenhouse. In Experiment 1, the plants were harvested at the mature seed stage. For Experiment 2, plants were harvested 5, 6, 7 and 8 weeks after sowing. In both experiments stems were collected and analysed for cell‐wall concentration and composition, and in vitro degradability of cell‐wall polysaccharide components by rumen micro‐organisms. The absence of syringyl‐type lignin was confirmed for the mutant lines by nitrobenzene oxidation and pyrolysis‐GC‐MS. Lignin concentration was the same for all three Arabidopsis lines, at all stages of maturity. The Arabidopsis stems were similar to forage legumes in that the potentially degradable cell‐wall fraction was very quickly degraded. Cell‐wall polysaccharide degradability did not differ among the Arabidopsis lines in the first experiment after 24‐h fermentations, but the cell‐wall polysaccharides of the fah1‐2 mutant line were less degradable after 96‐h than either the wild‐type or the fah1‐5 mutant. In contrast, in Experiment 2 no differences among lines were found for cell‐wall polysaccharide degradability after either 24‐ or 96‐h fermentations; however, signficantly higher levels of ester‐bound ferulic acid were found in the walls of the fah1 mutant lines. As expected, increasing stem maturity was correlated with reduced degradation of cell‐wall polysaccharides. These experiments indicate that either lignin composition, as measured by syringyl‐to‐guaiacyl ratio, does not alter cell‐wall degradability in Arabidopsis, or that the fah1 mutation has other effects on the cell walls of these mutants such that the impact of the change in syringyl‐to‐guaiacyl ratio is masked. © 1999 Society of Chemical Industry     

Effect of non-starch polysaccharides on the in vitro digestibility and rheological properties of rice starch gel

The starch digestibility and rheological properties of gels were evaluated in the presence of three non-starch polysaccharides (agar, xanthan gum and konjac glucomannan) with rice starch. Each polysaccharide was added to 30% (w/w) rice starch suspension at defined concentrations and starch gels were prepared. The extent of starch gel digestibility was determined by an in vitro method and rheological properties by a dynamic oscillatory test and a compression test. The added polysaccharides suppressed starch hydrolysis in the gels compared with the control, and a concentration dependency of this suppressive effect was observed. Adding agar and xanthan gum increased the storage shear modulus (G′) of starch gels, while adding konjac glucomannan decreased G′ values. The results indicate that the suppressive effect of non-starch polysaccharides on starch digestibility appears to be not only due to the rigidity of the gel, but also the interaction between starch and non-starch polysaccharides.     

Effects of simulated digestion in vitro on cell wall polysaccharides from kiwifruit (Actinidia spp.)

Cell wall polysaccharides are resistant to digestion and absorption in the human small intestine and are considered to be delivered to the colon in a chemically unaltered state. In this paper, pulp from green and gold kiwifruit was subjected to in vitro upper-intestinal tract digestion and the chemical and physical changes to cell wall polysaccharides (dietary fibre) were investigated. Yields of insoluble fibre decreased slightly with simulated digestion while soluble fibre yields increased. Constituent sugar and glycosyl linkage analysis of the soluble and insoluble fibre fractions revealed that the chemical composition and structure of the non-starch polysaccharides remained largely unchanged. However, the degree of methylesterification of galacturonic acid residues present in the pectin-rich soluble fibre fractions of both fruit decreased with treatment; size-exclusion chromatography detected changes in the molecular weight profiles of these fractions. These changes may affect the physicochemical properties and fermentability of kiwifruit dietary fibre in the large intestine.     

Influence of non-starch polysaccharides on the in vitro digestibility and viscosity of starch suspensions

The effects of adding non-starch polysaccharides (xanthan gum, guar gum, konjac glucomannan, and pectin) on the starch digestibility and viscosity of raw starch suspensions in a mixed system were determined. Each type of polysaccharide was added to high-amylose corn starch suspensions at defined concentrations. High-amylose rice starch suspensions mixed with xanthan and guar gum were prepared for comparison. The extent of starch digestibility was determined by an in vitro method, and the glucose diffusibility from the dialysis tube in the presence of polysaccharides was measured. The added polysaccharides were observed to decrease the starch digestibility in a mixed system. When compared at the same concentration, xanthan gum showed the most pronounced suppressive effect on starch digestibility and glucose diffusibility from the dialysis tube. The addition of polysaccharides increased the viscosity of the starch suspension. Significant relations were found between the extent of starch digestibility and the apparent viscosity at low shear rate.     

Fermentation characteristics of polysaccharide fractions extracted from the cell walls of maize endosperm

Cell walls were extracted from maize endosperm and separated into different polysaccharide fractions by sequential extraction with solutions of saturated Ba(OH)₂, demineralised water and 1 and 4 M KOH. Solubilised polysaccharides were collected after each extraction. Residues were collected following the extractions with demineralised water and 1 and 4 M KOH. The original cell wall (CW) material, extracts and residues were analysed for their fermentation characteristics using an in vitro cumulative gas production technique. The rate of fermentation of the alkali‐treated residues was faster than that of the original CW material, except for the 4 M KOH residue, which had a similar rate of degradation to the original CW material. The polysaccharides solubilised from the cell wall (extracts) were all rapidly fermented, more rapidly than both CW and residues. A division of the gas production profile into two phases using curve fitting was in good agreement with a division of the cell wall fermentation into the fermentation of arabinoxylans and cellulose. Therefore the likelihood of preferential degradation of arabinoxylans from the maize cell wall was discussed. The volatile fatty acid production pattern was fairly well explained by the fermentation rate and composition of the substrates. It was concluded that breaking the interactions of polysaccharides in the maize cell wall by mild alkali extraction increases the fermentability of maize cell walls in the gastrointestinal tract of farm animals. Contrarily, more severe alkali extractions will reduce the fermentability of maize cell walls. © 2002 Society of Chemical Industry     

Structural characterization and antioxidant activities of 2 water-soluble polysaccharide fractions purified from tea (Camellia sinensis) flower

Abstract: The water‐soluble crude polysaccharide tea flower polysaccharide (TFP), obtained from tea (Camellia sinensis) flower by boiling‐water extraction and ethanol precipitation, was fractionated by Sephadex G‐100 column chromatography, giving 2 polysaccharide fractions termed TFP‐1 and TFP‐2. The structural features of TFP‐1 and TFP‐2 were investigated by high‐performance liquid chromatography (HPLC), gel‐permeation chromatography (GPC), rheometer, infrared (IR) spectra, nuclear magnetic resonance (NMR) spectroscopy, atomic force microscope (AFM), and scanning electron microscope (SEM). Results indicated that TFP‐1 was composed of glucose: xylose: rhamnose: galactose = 1.0:1.2:0.81:0.98 with a molecular weight of 167.5 KDa, while TFP‐2 comprised glucose: xylose: rhamnose: arabinose = 1.0:0.76:2.3:2.3 with a molecular weight of 10.1 KDa. The ¹H NMR revealed that TFP‐1 contained α‐L‐Rhap, α‐D‐Galp, α‐D‐GalpNAc, α‐D‐Xylp, α‐D‐Glcp, and β‐D‐Glcp residues, while TFP‐2 was illustrated to have α‐L‐Rhap, α‐L‐Arap, α‐D‐Xylp, α‐D‐Glcp, and α‐D‐GlcpNAc residues. Antioxidant activities of these fractions were investigated using various in vitro assay systems compared with ascorbic acid. In conclusion, TFP‐2 exhibited the higher antioxidant activities and could be explored as a novel potential antioxidant. Practical Application: At present, commonly low‐grade tea is preferred to extract the tea polysaccharide, to take full advantage of tea flower resource to extract polysaccharides can greatly reduce the cost of tea products. Thus, the search for plant‐derived biomaterials from this study could generate natural value‐added products from underutilized tea plant waste and used as a medicinal agent against chronic health problems, such as cancers, aging, and atherosclerosis caused by reactive free radicals that produced from oxidation.     

Effect of extrusion on in situ ruminal protein degradability and in vitro digestibility of undegraded protein from different feedstuffs

BACKGROUND: The effect of extruding maize, barley, whole soybean (WSB), peas, lupins and soybean meal (SBM) on their in situ ruminal protein degradability and in vitro digestibility of the rumen undegraded protein (RUP) was studied. Two mixtures containing 0.75 WSB or lupins and 0.25 maize were also formulated. RESULTS: Extrusion of maize resulted in an increase of its effective protein degradability from 0.538 to 0.734 (P < 0.001), whereas the opposite occurred with barley (from 0.854 to 0.797; P < 0.001). Extrusion increased the in vitro digestibility of the RUP of both cereals, increasing therefore the amount of barley crude protein (CP) digested in the intestines (PDI) from 62 to 176 g kg^?1 CP (P < 0.01), whereas maize resulted in lower (332 versus 229 g kg^?1 CP; P < 0.01). Extrusion decreased (P < 0.001) the protein degradability of the three legume seeds and increased (P < 0.001) the in vitro digestibility of the RUP, resulting in a PDI increase (P < 0.001), from 60 to 367 g kg^?1 CP for peas, from 69 to 265 g kg^?1 CP for WSB and from 107 to 205 g kg^?1 CP for lupins. This effect was enhanced when WSB was extruded jointly with maize. The extrusion of SBM also resulted in an increase in the PDI from 296 to 384 g kg^?1 CP (P < 0.001). CONCLUSION: Extrusion decreases the rumen protein degradability of legume seeds, soybean meal and barley, and increases the digestibility of the RUP, resulting in an increase in the feed protein digested in intestine. The extrusion of soybean seeds together with maize enhances these effects. Copyright © 2008 Society of Chemical Industry     

The nutritive value for ruminants of thin stillage and distillers' grains derived from wheat,rye, triticale and barley

A study was conducted to determine nutrient degradabilities of thin stillages and distillers' grains derived from wheat‐, rye‐, triticale‐ and barley‐based ethanol production. In vitro protein degradabilities of wheat, rye, triticale and barley thin stillages were determined using a protease enzyme assay. One ruminally fistulated cow was used to determine ruminal nutrient degradabilities for wheat, rye, triticale and barley distillers' grains. Results of the in vitro study showed that the soluble protein fraction was highest for rye thin stillage and lowest for barley thin stillage. The degradation rate of the slowly degradable protein fraction was higher for wheat and triticale thin stillage than rye thin stillage and was higher for rye than barley thin stillage. Effective degradability of crude protein followed the order rye (659 g kg⁻¹) > triticale (632 g kg⁻¹) > wheat (608 g kg⁻¹) > barley (482 g kg⁻¹) thin stillage. Ruminal degradability of dry matter was highest for rye and lowest for barley distillers' grains. Ruminal degradability of dry matter was also higher for wheat than triticale distillers' grains. Crude protein from barley distillers' grains had a lower ruminal degradability relative to crude protein from wheat and rye distillers' grains. Ruminal degradability of neutral detergent fibre was highest for rye distillers' grains (470 g kg⁻¹), intermediate for wheat and triticale distillers' grains (average 445 g kg⁻¹) and lowest for barley distillers' grains (342 g kg⁻¹). It was concluded that thin stillage and distillers' grains derived from barley had a lower nutritive value for ruminants compared with those derived from wheat, rye and triticale. © 2000 Society of Chemical Industry     

Forage quality variation among maize inbreds: Relationships of cell-wall composition and in-vitro degradability for stem internodes

Forty-five inbred maize (Zea mays L) lines were evaluated for genetic variation in stem cell-wall concentration, composition and degradability, and for relationships among cell-wall components and polysaccharide degradability. Cell-wall neutral sugars, uronic acids, Klason lignin, and ester- and ether-linked phenolic acids were measured on lower stem internode samples collected at the time of silking in 2 years. Twenty-four and 96 h in-vitro ruminal fermentations were used to determine the rapidly and potentially degradable cell-wall polysaccharide fractions, respectively. Genetic variation (P < 0.05) was found for all measures of cell-wall composition and many estimates of rapidly and potentially degradable cell-wall polysaccharide components. Inbred line means varied by 50–300% for most traits. Three brown midrib mutant inbred lines included in the study were not the lowest in lignin content nor did they exhibit the greatest cell-wall degradabilities in this population of inbred maize. Year of growth (environment) influenced (P < 0.05) cell-wall traits even though reproductive physiological maturity at sampling was similar in both years. Degradability of the cell-wall polysaccharide components were intercorrelated (P < 0.05) within the rapidly and potentially degradable fractions, but rate and extent of degradation of the cell-wall components were not correlated (P > 0.05), except for uronic acids. A multiple regression model of principal components (R² = 0.41, P < 0.05) indicated that cell-wall lignification and substitution of wall polymers with phenolic and uronic acids were negatively associated, and pectic substances were positively related with rapid polysaccharide degradation. Very little of the variation (R² = 0.15, P < 0.05) in potential cell-wall polysaccharide degradation could be explained by this multiple regression analysis. There is a large degree of genetic variation among current inbred maize lines for stem cell-wall quality traits, which should allow improvement of maize as a forage crop. Because of the complex matrix interactions in cell-wall organization, however, no single cell-wall component, or simple combination, can accurately predict degradability of maize cell walls.     

Indigestible fraction of okara from soybean: composition,physicochemical properties and in vitro fermentability by pure cultures of <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> and <Emphasis Type="Italic">Bifidobacterium bifidum</Emphasis>

Major non-digestible components of soybean seeds and okara were determined by an in vitro enzymatic-physiological method, alternative to dietary fibre. Total indigestible fraction was higher in okara (41.6%) than in seeds (28.5%), and consisted of soluble and insoluble fractions, mainly composed of non-starch polysaccharides, klason lignin and resistant protein. Total protein was lower in okara (32.29%) than in seeds (46.97%), as were oil (14.72% okara–20.89% seeds) and ash contents (3.18% okara–4.60% seeds). In vitro digestibility of protein was lower for okara (84.3%), than for soybean seed (91.8%). Moreover, okara showed high swelling (10.54 ± 0.14 mL/g d.w.) and water retention capacity (8.87 ± 0.06 g/g d.w.) and was fermented in vitro to a greater extent by Bifidobacterium bifidum (29.8%), than by Lactobacillus acidophilus (8.3%). For its composition, physico-chemical properties and bifidogenic capacity in vitro, okara is a potential candidate to be a prebiotic fibre-rich ingredient of new functional foods. An erratum to this article can be found at     

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.     

Non-starch polysaccharides from sunflower (Helianthus annuus) meal and palm kernel (Elaeis guineenis) meal—preparation of cell wall material and extraction of polysaccharide fractions

Two different chemical methods, sequential extraction with alkali and sodium chlorite and treatment with 4-methylmorpholine N-oxide (MMNO), were applied to the extraction of non-starch polysaccharides (NSP) from the enzymically deproteinated, water-insoluble cell wall materials of sunflower (Helianthus annuus L) meal and palm kernel (Elaeis guineensis Jacq) meal. The NSP content accounted for 550 g kg^?1 (sunflower meal) and 750 g kg^?1 (palm kernel meal) of the cell wall materials. Neither of the treatments alone was capable of solubilising more than about half of the original NSP. Combined treatment using alkali/chlorite followed by MMNO completely dissolved cell wall material from palm kernel meal, whereas a small residue (40 g kg^?1 of original NSP) was left in sunflower meal. Loss of NSP occurred with both methods (total NSP recovery ranging from 88% for alkali/chlorite extraction of sunflower to 64% for MMNO extraction of palm kernel). Due to differences in solubility revealed upon acidification and/or dialysis, extracts became subdivided into precipitates and soulble fractions. The sugar composition of the resulting fractions enabled a tentative identification of teh major non-starch polysaccharides; sunflower meal was found to contain cellulose, (acidic) xylans, polyuronide-containing fractions and xyloglucan; palm kernel meal was found to contain mannans, cellulose and xylans, with the major part of the mannans originating from the endosperm and the xylans being almost exclusively located in the endocarp.     

沙棘多糖分离纯化及抗氧化活性

分离纯化沙棘多糖（sea buckthorn (Hippophae rhamnoides) polysaccharides,SBP）,并对其单糖组分、结构表征及体外抗氧化活性进行分析。通过水提醇沉、Sevag法除蛋白得到沙棘粗多糖,利用DEAE-52纤维素柱对其进行分离纯化得到中性多糖SBP-I和酸性多糖SBP-II、SBP-III 3 种组分。单糖组分结果表明,SBP-I由物质的量比为1.18∶1∶2.20∶32.17∶1.45的阿拉伯糖、木糖、甘露糖、葡萄糖及半乳糖组成;SBP-II由物质的量比为1∶0.28∶1.02∶0.20的木糖、甘露糖、葡萄糖及半乳糖组成;SBP-III由物质的量比为1∶2.15∶0.28的木糖、葡萄糖及半乳糖组成;红外光谱测定表明,3 种组分均具有多糖的特征吸收峰;体外抗氧化实验结果表明,粗多糖及3 种纯化多糖组分均具有较好的抗氧化性且随样品质量浓度的增加抗氧化活性也随之升高,抗氧化能力大小顺序为：VC＞SBP-III＞SBP-II＞SBP-I＞粗多糖。     

Composition and in-vitro digestibility of carbohydrates of wheat plants harvested at bloom and soft-dough stages

Wheat plants (Triticum aestivum) were harvested at the bloom and soft-dough stages, separated into leaves + sheaths, stems and spikes, and the effect of stage of maturity on neutral detergent fibre (NDF) composition and degradability was studied, the accumulation of starch in the spikes compensated for the decrease in the degradability of NDF polysaccharides so that the in-vitro digestibility of the organic matter (OM) was not changed between the bloom and soft-dough stages. Minor compositional changes occurred in the NDF of the various botanical fractions which can hardly explain the drop in NDF degradability with maturity. There was a decline in the ratio of hemicellulose to lignin, and the changes in NDF-monosaccharide degradability were probably related to the extension of covalent bonding between those matrix components during maturation. Irrespective of botanical fraction and maturity stage, NDF xylose was less digestible than NDF glucose. Between bloom and soft-dough stages there was an increase of 36% in the yield of digestible OM.     

Water-extracted polysaccharides of selected cereals and influence of temperature on the extractability of polysaccharides in sorghum

Non-cellulosic and non-starchy (I₂-KI negative) glucose-rich polysaccharides from wheat, ragi, rice and sorghum were extracted with water at ambient temperature (25°C). Ethanolic fractional precipitation of the polysaccharides yielded a number of fractions containing varying proportions of hexoses (0.7–98%) and pentoses (1–56%). Polysaccharides from sorghum were also extracted at 4, 55°C and at boiling water temperature. Prior amylolysis of the sorghum flour followed by extraction at boiling water temperature was found to give a better yield of non-starch glucose-rich polysaccharides.