Changes in carbohydrates during growth and development of bajra (Pennisetum typhoides), jowar (Sorghum vulgare) and kangni (Setaria italica)

Qualitative and quantitative changes in carbohydrate contents have been studied during the growth and development of bajra (Pennisetum typhoides), jowar (Sorghum vulgare) and kangni (Setaria italica). Besides traces of glucofructosans, sucrose, glucose and fructose are the principal sugars present in the leaf and stem tissues of all stages of growth. As growth proceeds, water-soluble carbohydrates increase in the stem, attaining a maximum value at flowering and initiation of seed formation and thereafter steadily decline reaching a low value at maturation. Cellulose also increases with growth in bajra and jowar stem. This increase is more marked at early stages of growth. Starch content gradually increases with the simultaneous decrease in free and total reducing sugars in the developing grains. Some fructosans are also synthesised in the grains during their formation and presumably serve as intermediates in the synthesis of starch.     

An assessment of the protein quality and vitamin b content of commonly used fermented products of legumes and millets

Fermented products of legumes, Bengal gram dhal (Cicer arietinum) and green gram dhal (Phaseolus aureus), and millets, bajra (Pennisetum typhoideum), jowar (Sorghum vulgare) and ragi (Eleucine coracana), were analysed for protein quality and vitamin B content. Fermentation reduced total crude protein by 6-8 % in the legume products and 4-6% in the millet products of bajra and ragi. No reduction in crude protein was observed in fermented jowar products. Temperature of batters increased considerably on fermentation, while pH decreased. The protein efficiency ratio (PER) and the true digestibility (TD) of legume products were not altered by fermentation, the biological value (BV) and net protein utilisation, (NPU), of Bengal gram dhokla improved significantly (P<0.05). The TD of fermented jowar increased significantly (P < 0.05) but not that of ragi, bajra and the legume products. BV and NPU of both jowar and ragi products increased significantly on fermentation (P<0.05) but not that of bajra. The thiamin and riboflavin contents of both the legume and millet products increased with increase in fermentation time. Steaming and cooking after fermentation reduced the thiamin and riboflavin content. However, fermentation after cooking of millet batters increased the levels of both vitamins markedly.     

Alternate Economical Starchy Substrates for the Production of 70% Sorbitol

In view of the soaring prices of corn and tapioca starch, use of their hydrolysate in the production of 70% sorbitol became less remunerative. Therefore, an economical alternative is explored by using hydrolysates of cereal flours, namely, rice (Oryzae sativa), wheat (Triticum aestivum), jowar (Sorghum vulagare) and bajra (Pennisetum typhoideum). A protocol is devised to a) prepare their high DE hydrolysates, b) purify it after saccharification, c) monitor the chemical characteristics of concentrated hydrolysate, as fedstock for Raney nickel catalyzed pressure hydrogenation and d) finally prepare 70% sorbitol. Merits and demerits of hydrolysates of these cereal flours are discussed in terms of operational limitations and percentage recovery, the governing factors for their industrial acceptability. Rice flour hydrolysate appears to be an alternative substrate, operationally and economically.     

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.     

A comparison of the insoluble residues produced by the Klason lignin and acid detergent lignin procedures

Two methods—Klason lignin (KL) and acid detergent lignin (ADL)— for determining lignin concentration in plants were compared using stem material from lucerne (Medicago sativa L), cocksfoot (Dactylis glomerata L) and switchgrass (Panicum virgatum L), at three stages of maturity, and leaf samples from lucerne and cocksfoot. For all forages, KL values were higher than ADL values. Lucerne samples, which had crude protein levels twice that of the grass species, had KL values that were only 30–40% higher than ADL values; in grasses, KL values were 200–300% greater than ADL values. The addition of nitrogenous materials (bovine serum albumin, lysine, and ammonium sulfate) to commercial xylan and cellulose did not result in additional KL residue. Pyrolysis-GC-MS revealed that both residues appeared to be similar to the orginal plant lignin and did not appear to be contaminated with carbohydrate or protein. The higher values for grass KL residues were not due to protein con- tamination or incomplete hydrolysis of carbohydrates, but were more likely due to the solubilization of lignin components by the ADL treatment. KL values may give a more accurate quantification of the total lignin within forage plants.     

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     

The effect of field drying on the non-structural carbohydrate composition in vetch hay

Common vetch (Vicia sativa L) was harvested and allowed to dry in the open air. The composition of fresh forage in non-structural carbohydrates varied markedly between years, the contents of sugars and starch in both leaves and stems being much higher in 1990-91 than 1991-92. Field drying produced a significant decrease in the amounts of these carbohydrates. The total losses of sugars and starch in hay, expressed as losses of dry matter, ranged from 28 to 15 g kg^-1, depending on the year.     

Lignin and Hydroxycinnamic Acids in Walls of Brown Midrib Mutants of Sorghum,Pearl Millet and Maize Stems

The characteristics of walls from stems of brown-midrib ( bmr ) mutants from Sorghum bicolor (L) Moench bmr6 and bmr18 (watery- to milky-grain stage), Pennisetum americanum (L) Leeke KS81-1089 (soft-dough stage) and Zea mays L bm3 (early-dent stage) with respect to the types of linkages of hydroxycinnamic acids to wall polymers and to structural features of their lignins were investigated. The lignin content of all mutants, determined using the acid detergent lignin procedure, was significantly lower than that of their normal counterparts. There was, however, no significant differences in total lignin contents between bmr and normal lines as determined by the acetyl bromide procedure or the sum of the acid-insoluble (Klason) lignin and acid-soluble lignin. It is suggested that this behaviour could be explained if bmr mutants are characterised by higher amounts of lignin with a lower degree of polymerisation than normal lines. The lowered S/V ratio and lowered total yield of alkaline nitrobenzene oxidation products in lignin from bmr mutants was confirmed. No etherified p -coumaric acid was found in any sample tested, except the normal line of pearl millet. The concentration of etherified ferulic acid, which is probably involved in ester-ether bridges between lignin and polysaccharides, was lower in bmr mutants than in the normal plants. The low content of ferulic acid bridges in bmr mutants may contribute to the elevated digestibilities of their stems.     

Lignification of switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii) plant parts during maturation and its effect on fibre degradability

Five cultivars of switchgrass (Panicum virgatum L) and four cultivars of big bluestem (Andropogon gerardii Vitman) were harvested at vegetative, boot and heading stages of maturity. Leaf and stem fractions were analysed for detergent fibre composition and 48-h ruminal in-vitro degradability, ester- and ether-linked non-core lignin phenolic acids, and core lignin composition. Big bluestem leaves contained more neutral detergent fibre than switchgrass, but general composition of the fibre did not differ. Stem fibre of switchgrass had relatively lower levels of cellulose and lignin at the vegetative stage than observed in big bluestem. Esterified and etherified p-coumaric and ferulic acid concentrations were generally higher in switchgrass plant parts. Yield of nitrobenzene oxidation products from core lignin was greater for switchgrass leaves, but very little difference in composition was noted. Leaf tissue contained lower concentrations of all lignin components than stems. Maturation resulted in increased total lignification, but all components did not respond in the same manner. Variation for all measures of lignification seemed to be as great within species as between the grass species. Degradability of fibre declined with maturation. The only species difference was that switchgrass fibre was more degradable at the vegetative stage. Relationships between lignification and fibre degradability were in agreement with some, but not all, previously reported relationships. Concentration of core lignin was only a significant predictor of fibre degradability when the relationship was examined across maturity stages. Within a stage of maturity, lignin composition was more closely related to fibre degradability than was concentration. However, the best predictors of fibre digestibility differed among species, plant part and maturity.     

Comparison of common lignin methods and modifications on forage and lignocellulosic biomass materials

BACKGROUND: A variety of methods have been developed for estimating lignin concentration within plant materials. The objective of this study was to compare the lignin concentrations produced by six methods on a diverse population of forage and biomass materials and to examine the relationship between these concentrations and the portions of these materials that are available for utilisation by livestock or for ethanol conversion. RESULTS: Several methods produced lignin concentrations that were highly correlated with the digestibility of the forages, but there were few relationships between these methods and the available carbohydrate of the biomass materials. The use of Na₂SO₃ during preparation of residues for hydrolysis resulted in reduced lignin concentrations and decreased correlation with digestibility of forage materials, particularly the warm‐season grasses. CONCLUSION: There were several methods that were well suited for predicting the digestible portion of forage materials, with the acid detergent lignin and Klason lignin method giving the highest correlation across the three types of forage. The continued use of Na₂SO₃ during preparation of Van Soest fibres needs to be evaluated owing to its ability to reduce lignin concentrations and effectiveness in predicting the utilisation of feedstuffs and feedstocks. Because there was little correlation between the lignin concentration and the biomass materials, there is a need to examine alternative or develop new methods to estimate lignin concentrations that may be used to predict the availability of carbohydrates for ethanol conversion. Copyright © 2011 Society of Chemical Industry     

Biodegradation of plant cell walls,wall carbohydrates,and wall aromatics in wheat grown in ambient or enriched CO2 concentrations

Mature internodes from wheat (Triticum aestivum L) grown in control (ambient at c 370 μnol mol^?1) or enriched (to 550 μmol mol^?1) concentrations of atmospheric CO₂ in the free-air CO₂ enrichment (FACE) system were analyzed for potential changes in biodegradation of constituents due to predicted increases in atmospheric levels of CO₂. The first internodes below the grain were incubated with the lignocellulose-degrading white rot fungus, Phanerochaete chrysosporium K-3, or incubated without microorganisms. Plant samples were then analyzed for dry weight loss, disposition of specific cell types to biodegradation using electron microscopy, carbohydrates and lignin using solid state NMR spectroscopy, and ester-and ether-linked aromatics using gas chromatography. Phanerochaete chrysosporium extensively degraded stems cells (c 75%) and both carbohydrate and aromatic portions of the wheat stems; proportionately more carbohydrates were removed by the fungus from the stems. Enriched CO₂ did not affect the chemical composition of wheat stems or the biodegradation by P chrysosporium of plant cell walls or wall components for the most part. Data from various methods all indicated that enriched CO₂ did not substantially alter the biodegradation of wheat cell wall internodes or wall components. Evidence was not found for an influence on C cycling due to CO₂ concentrations in this study.     

Responses of Lotus corniculatus to environmental change. 2. Effect of elevated CO2, temperature and drought on tissue digestion in relation to condensed tannin and carbohydrate accumulation

Clonal plants of three genotypes of Lotus corniculatus (cv Leo) were grown in eight controlled environments under combinations of two temperature regimes, two CO₂ concentrations and two watering regimes. Condensed tannins (proanthocyanidins), in-vitro digestibility, initial rates of gas evolution (as an indicator of the initial rates of fermentation of the substrate), volatile fatty acid evolution, and non-structural carbohydrate (NSC) levels were determined in leaves, stems and roots at full flowering. Under control conditions (average midsummer conditions in the United Kingdom) the total condensed tannin content of leaves varied six-fold between genotypes but condensed tannin contents in stems and roots were similar. Condensed tannin levels were significantly increased in leaves and stems of all three genotypes by doubling the CO₂ concentration while raising the temperature towards the optimum for growth significantly reduced condensed tannin levels. Drought stress significantly reduced condensed tannin levels in leaves and, particularly, in roots. Nutritive value was inversely related to condensed tannin levels in leaves and a negative relationship was observed between condensed tannin concentrations of more than 25–30 g kg⁻¹ dry matter and the initial rates of gas evolution when subjected to in-vitro fermentation with rumen micro-organisms. In leaves, digestibility was significantly increased by drought and by increasing temperature but reduced by high CO₂. In stems, digestibility was significantly increased by drought, but not significantly affected by increasing temperature, or by high CO₂ alone. In roots, digestibility was significantly increased by drought, and decreased by increasing temperature or CO₂. Increasing the growth temperature towards optimum growth reduced the content of NSC in all tissues with the greatest changes occurring in root tissue. Doubling the CO₂ concentration increased NSC levels in leaves and stems with starch content more than doubled under high CO₂ while, in roots, increased levels were only observed in combination with drought stress. There was a linear correlation between condensed tannin concentration and total NSC that was positive for leaves, neutral for stems and negative for roots. The relationship between carbohydrate levels and rates of gas production was negative for leaves and positive for stem and roots. © 1999 Society of Chemical Industry     

Lignin and Fiber Compositional Changes in Forages Over a Growing Season and Their Effects on In Vitro Digestibility

The composition of lignin and fiber was investigated in three forages, alfalfa (Medicago sativa L.), tall fescue (Festuca arundinacea Schreb.), and orchardgrass (Dactylis glomerata L.) hays, and the vegetative parts of corn (Zea mays) and wheat (Triticum aestivum L.) plants collected over the 1982 growing season to determine how lignin in different plants changes with plant growth and how this relates to changes in fiber and digestibility measures. The composition of lignin (by nitrobenzene oxidation) varied with the plant, harvesting frequency, and maturity, although changes were often more pronounced early in the growing season. Fiber composition and in vitro digestibility varied, but variability was spread over the entire growing season. Coefficients of determination between lignin components and fiber or digestibility measurements were highly forage dependent. The best predictor (among lignin components) of NDF or ADF or lignin content was p-hydroxybenzaldehyde for alfalfa, a mixture (acetovanillone and 4-allyl-2,6-dimethoxyphenol) for corn plant and orchardgrass, and syringic acid for tall fescue and wheat plant. Similarly, the best predictor of digestibility by a lignin component was the mixed component for alfalfa and orchardgrass and syringic acid for the others.     

Comparative study of carbohydrates in the two major species of jute (Corchorus capsularis and Corchorus olitorius

Unretted and retted bark and stem of Corchorus olitorius L and retted stem of C capsularis L, two species of jute, were analysed for ash, lignin, low molecular weight carbohydrates and polysaccharides. The results are compared with those from C capsularis published earlier. The unretted bark and stem of C olitorius contained less low molecular weight carbohydrates than the corresponding fractions of C capsularis. C olitorius bark contained less cellulose and more hemicellulose than C capsularis, particularly after retting. Xylans isolated from the retted fibre and stem of C olitorius were found to have a similar composition to those from C capsularis.     

Effects of seed rate,nitrogen level and leaf age on the yield of extracted protein from five different crops in West Bengal

The yield of leaf protein from five different crops grown at different seed rates and nitrogen levels was studied. Bajra (Pennisetum typhoideum Rich.) and mustard (Brassica nigra Koch) gave large protein yields. Harvesting just before the initiation of flowering produced the highest yield except with hybrid Napier (P. typhoideum x P. purpureum) and turnip (Brassica rapa L.). With the latter, maximum yield was obtained 45–52 days after sowing, and with the former 62 days. Seed rates of 120–150 kg/ha (4–5 times normal) were used with bajra and ragi (Eleusine coracana Gaertn), 30 kg/ha with mustard and 8 kg/ha with turnip. The yield of extracted protein was not increased by giving mustard more than 60, ragi more than 160 and bajra more than 240 kg N/ha. The N level for maximum response was not reached with turnip and hybrid Napier. More of the leaf protein was extracted from mustard and turnip than from the other species; mustard and turnip also gave the largest yields of protein (7.6 and 5.7 kg/ha/day respectively).     

Cell wall composition and degradability of forage stems following chemical and biological delignification

Chemical and biological delignification methods were used to investigate the relationship between the concentration and composition of lignin and degradation of forage cell walls. Stem material from lucerne (Medicago sativa L), smooth bromegrass (Bromus inermis Leyss) and maize (Zea mays L) stalks was treated with alkaline hydrogen peroxide, potassium permanganate, sodium chlorite, sodium hydroxide, nitrobenzene, and the lignolytic fungus Phanerochaete chrysosporium. Klason lignin and esterified and etherified phenolic acids were delermined. Cell wall neutral sugar and uronic acid composition and the extent of in-vitro degradability were measured. Chemical delignification generally removed lignin. but the fungal treatment resulted in the removal of more polysaccharide than lignin. The concentrations of esterfied and etherified p-coumaric and ferulic acids were generally reduced in treated cell walls; chlorite treatment preferentially removing p-coumaric acid whereas nitrobenzene treatment removed more ferulic acid. Syringyl moieties were completely removed from the core lignin polymer by nitrobenzene treatment of forage stems. Alkaline hydrogen peroxide and nitrobenzene were generally the most effective delignification treatments for improving polysaccharide degradability, with the grass species responding similarly to delignification whereas lucerne was somewhat less responsive. Fungal delignification, under these experimental conditions, did not improve cell wall degradability of these forages. Multiple regression and covariate analyses indicated that the lignin components measured were not powerful predictors of cell wall degradability. Neither the concentration nor the composition of the lignin fractions was consistently correlated with degradation. This lack of effect was attributed to the more generalised disruption of the cell wall matrix structure by delignification treatments.     

Analysis of cocoa pulp and the formulation of a standardised artificial cocoa pulp medium

Results of analyses of cocoa pulp from the Ivory Coast, Nigeria and Malaysia are reported. These include pH, viscosity and a_w measurements and concentration of soluble sugars, vitamins and anions. Pulp from Malaysian cocoa pods had a higher water content, lower citrate, hemicellulose, lignin and pectin concentration and a higher pH than Ivorian or Nigerian cocoa pods. The composition of a defined cocoa pulp medium which has the same overall composition, pH, a_w and viscosity as cocoa pulp is described. The defined cocoa pulp medium supported the growth of yeasts, lactic acid bacteria and acetic acid bacteria.     

Characterization of p‐coumarate accumulation,p‐coumaroyl transferase,and cell wall changes during the development of corn stems

BACKGROUND: Developmental changes occur in corn (Zea mays L.) stems from cell initiation to fully mature cell types. During cell wall maturation the lignin is acylated with p‐coumarates (pCA). This work describes characterization studies of the p‐coumaroylation process in relation to corn stem development. RESULTS: Corn plants from three locations were harvested and tissues were analyzed from all nodes and even‐numbered internodes above soil line. Changes in carbohydrates reflect a shift to lignification at the expense of structural polysaccharide synthesis. Accumulation of pCA paralleled the incorporation of lignin while ferulate (FA) remained relatively constant as a proportion of the cell wall (5–7 g kg^?1 CW). The p‐coumaroyl transferase (pCAT), which is responsible for attaching pCA to lignin monomers, displayed maximum levels of activity in the middle region of the stem (internodes 10–12, 2–3 nmol L^?1 min^?1 mg^?1). The syringyl content as a proportion of the total lignin did not change significantly with cell wall maturation although there was a trend towards increased amounts of syringyl units in the more mature cell walls. CONCLUSIONS: Incorporation of pCA into corn cell walls not only mirrored lignification but the pCAT activity as well. Levels of pCAT activity may be an indicator of rapid lignification specifically for syringyl type lignin. Copyright © 2008 Society of Chemical Industry     

Non-structural carbohydrate partitioning in Phaseolus vulgaris after vegetative growth

This study provides information on the concentration and quantity of starch, reducing sugars, total sugars, and non-reducing oligosaccharides in the organs of the common bean plant (Phaseolus vulgarisL cv Jamapa) during growth. The following observations were made: (1) the root, stems and branches were temporary carbohydrate storage organs; (2) until 80 days after sowing (DAS), the leaves were the major contributors to the non-structural carbohydrates of the whole plant; (3) during the developmental period studied, non-structural carbohydrate content in the rachis and pulvinus changed frequently; (4) the pod walls contained between 5 and 8% of total sugars at 72 DAS and by maturity soluble sugars diminished to less than 1%; (5) during seed growth (until 80 DAS), the pod walls contained between 11 and 18% starch (dry weight basis) and by maturity this carbohydrate had decreased to 2% of dry weight; and (6) starch represented the major non-structural storage carbohydrate in mature seeds (29%), as opposed to soluble sugars, which amounted to 2·3% of the dry weight.     

Cell wall fermentation kinetics are impacted more by lignin content and ferulate cross‐linking than by lignin composition

BACKGROUND: We used a biomimetic model system to ascertain how reductions in ferulate–lignin cross‐linking and shifts in lignin composition influence ruminal cell wall fermentation. Primary walls from maize cell suspensions with normal or reduced feruloylation were artificially lignified with various monolignols previously identified in normal, mutant, and transgenic plants. Cell wall fermentability was determined from gas production during in vitro incubation with rumen microflora and by analysis of non‐fermented polysaccharides. RESULTS: Hemicellulose fermentation lag time increased by 37%, rate decreased by 37%, and the extent declined by 18% as cell wall lignin content increased from 0.5 to 124 mg g^?1. Lignification increased lag time for cellulose fermentation by 12‐fold. Ferulate–lignin cross‐linking accounted for at least one‐half of the inhibitory effect of lignin on cell wall fermentation. Incorporating sinapyl p‐coumarate, a precursor of p‐coumaroylated grass lignin, increased the extent of hemicellulose fermentation by 5%. Polymerizing varying ratios of coniferyl and sinapyl alcohols or incorporating 5‐hydroxyconiferyl alcohol, coniferaldehyde, sinapyl acetate, or dihydroconiferyl alcohol into lignin did not alter the kinetics of cell wall fermentation. CONCLUSION: The results indicate that selection or engineering of plants for reduced lignification or ferulate–lignin cross‐linking will improve fiber fermentability more than current approaches for shifting lignin composition. Copyright © 2008 Society of Chemical Industry