Barley Husk Research Articles

Removal of solar red BA textile dye from aqueous solution by low cost barley husk: Equilibrium, kinetic and thermodynamic study

AbstractThe present study investigates the sorption potential of barley husk for the removal of solar red BA from aqueous solution. Sorption capacity, q (mg/g), of barley husk decreased with increasing initial dye concentration. The sorption equilibrium established within 90 min using 0.10 g biosorbent while it was prolonged to 135 min with increasing amount of biosorbent (0.25–0.50 g). The equilibrium data were fitted to Freundlich and Langmuir isotherms at different biosorbent doses. The results indicated the applicability of Freundlich isotherm at low‐biosorbent dose. Pseudo‐second‐order kinetic model was found to be best fit to the biosorption data with three biosorbent doses. The equilibrium thermodynamic data for the adsorption of the dyes gave ΔG0 values −79.77 kJ/mol at 303 K indicated the process to be occurred spontaneously at low temperature. FTIR analysis and SEM imaging of biosorbent were also carried out.L'objectif de la présente étude est d'analyser le potentiel de sorption du son d'orge afin d'éliminer le BA rouge solaire contenu dans les solutions aqueuses. La capacité de sorption, q (mg/g), du son d'orge diminue lorsque les concentrations initiales de colorant augmentent. L'équilibre de sorption a été établi à 90 min en utilisant 0.10 g de biorsorbant, mais a été prolongé à 135 min avec une plus grande quantité de biorsorbant (0.25 à 0.50 g). Les données relatives à l'équilibre ont été harmonisées aux isothermes de Freundlich et Langmuir à différentes doses de biosorbant. Les résultats indiquent que l'isotherme de Freundlich est applicable avec de faibles doses de biosorbant. Selon les résultats, le modèle cinétique de pseudo‐second ordre correspond le mieux aux données de biosorption avec les trois doses de biosorbant. Les données de l'équilibre thermodynamique pour l'adsorption des colorants ont permis d'obtenir des valeurs de ΔG0 de −79.77 kJ/mol à 303 K, ce qui indique que le processus s'est déroulé spontanément à faible température. Des analyses FTIR et une imagerie par MEB des biosorbants ont également été réalisées. © 2010 Canadian Society for Chemical Engineering

Lipid damage during frozen storage of Atlantic halibut (Hippoglossus hippoglossus) in active packaging film containing antioxidants

The use of peroxide value (PV), free fatty acids (FFA), thiobarbituric acid reactive substances (TBARS) and p-anisidine value (PA) proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation in samples of Atlantic halibut throughout frozen storage. After twelve months, the FFA values in the samples packaged with the film containing natural antioxidants (extracted from barley husks) were similar to the FFA value in the control sample after 9 months. Maximum peroxide value in the samples packaged with the antioxidant-containing film was found one month after the maximum value observed in the control sample. After six months, the concentration of malondialdehyde in the control sample was approximately 30–50% higher than in samples packaged in film containing antioxidants. The results confirm the efficacy of natural antioxidants derived from barley husks and antioxidant active packaging film in slowing down lipid hydrolysis and increasing the oxidative stability of Atlantic halibut flesh.

Enzymatic hydrolysis of autohydrolyzed barley husks

BACKGROUND: Barley husks were subjected to non-isothermal autohydrolysis of different severities, yielding a liquid phase rich in hemicellulose-derived compounds and a solid phase, composed mainly of cellulose and lignin. This solid phase was subjected to enzymatic hydrolysis in order to assess the effects of severity on the susceptibility of substrates to enzymatic hydrolysis. The effects of the liquid to solid ratio (LSR, in the range 6 to 18 g g−1) and cellulase to substrate ratio (CSR, in the range 3.3 to 8.2 FPU g−1) on the enzymatic hydrolysis were assessed. RESULTS: Up to 25.8 g oligomers per 100 g raw material were present in liquors from the hydrothermal processing. Enzymatic hydrolysis of solid phases obtained under selected conditions (log Ro = 4.14, LSR = 6 g g−1 and CSR = 5.8 FPU g−1) yielded glucose concentrations up to 67 g L−1 (corresponding to cellulose to glucose conversions close to 100%). CONCLUSION: It was shown that autohydrolysis is an effective method for improving the enzymatic susceptibility of barley husks. High cellulose conversions resulting in high glucose yields were achieved by enzymatic hydrolysis at low LSR and CSR. The liquid fraction obtained upon autohydrolysis contained large amounts of hemicellulose-derived compounds. Copyright © 2010 Society of Chemical Industry

Competition between domestic dogs and Ethiopian wolf (Canis simensis) in the Bale Mountains National Park, Ethiopia

AbstractThe potential effects of the domestic dogs (Canis familiaris) on the Endangered Ethiopian wolf (Canis simensis) through exploitative and interference competition were studied in the Web Valley of Bale Mountains national park between November 2001 and February 2003. All dogs were owned in the study area and no feral dogs were reported or observed during the research period. The diet of domestic dogs was dominated by barley husks and human faeces which contributed 45% and 20.7% of the total 382 meals observed during focal watch observations. Analysis of dog faeces provided similar results with barley husks, human faeces and animal carcasses occurring in 86.8%, 21.4% and 19.4% of the 1200 faecal samples analysed. Both focal watch and faecal analyses revealed that rodents contributed only a very small proportion of the diet of dogs accounting for only 4.2% of the focal watch and 2.8% of the faecal analysis of roaming dogs. As Ethiopian wolves fed almost exclusively on rodent year round, no significant exploitative competition between dogs and wolves were assessed. Only small proportion of the domestic dogs roamed in the Ethiopian wolf range and interference competition did not appear to be a serious threat for the Ethiopian wolf.

Evaluation of the effectiveness of a new active packaging film containing natural antioxidants (from barley husks) that retard lipid damage in frozen Atlantic salmon (Salmo salar L.)

Salmon is a perishable fish that contains high level of PUFAs (polyunsaturated fatty acids), which have many positive effects on human health, but which are extremely susceptible to oxidation. The development of new food packaging films by incorporation of antioxidants is expected to improve the shelf life of food and thus increase consumer safety and health. Determination of peroxide value (PV), conjugated dienes (CD), conjugated triene hydroperoxides (TH), free fatty acids (FFA), totox value (TV), thiobarbituric acid index (TBARS) and p-anisidine value (AV) by established methods proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation in samples of salmon during frozen storage. The results obtained confirm the efficacy of natural antioxidants derived from barley husks (NABH) in slowing down lipid hydrolysis and increasing the oxidative stability of salmon flesh. This study demonstrates the potential usefulness of natural antioxidants extracted from barley husks in the development of active packaging films for food preservation.

Barley husk and coconut shell reinforced polypropylene composites: The effect of fibre physical, chemical and surface properties

The main objective of this research was to study the potential of grain by-product such as barley husk, coconut shell as reinforcements for thermoplastic as an alternative or together with wood fibres. Thermal degradation characteristics of those fibres were studied to investigate the feasibility of these fibres to the processing point of view. The particle morphology and particle size was investigated by scanning electron microscopy. Water absorption properties of the fibres were studied to evaluate the viability of these fibres as reinforcements. The chemical composition and surface chemistry of those fibres were also determined to evaluate its importance in determining the end-use properties of composites. Polypropylene composites were fabricated using a high speed mixer followed by injection moulding with 40 wt.% of fibre load. Tensile and Charpy impact strength of resulting composites were investigated.

Adsorption of cationized barley husk xylan on kraft pulp fibres: influence of degree of cationization on adsorption characteristics

A water-soluble (glucurono)arabinoxylan (GAX) was isolated from barley husk using chlorite delignification followed by alkaline extraction and enzymatic purification of the extract. The isolated xylan was shown to adsorb on bleached softwood kraft fibres, but the degree of adsorption was rather low under the applied conditions. This can be explained by the inhibited adsorption of GAX molecules with a relatively high degree of arabinofuranosyl substitution, as indicated by iodine complexation and neutral carbohydrate analysis of the non-adsorbing xylans. In order to increase the driving force for adsorption of the more highly substituted GAX, the xylan was cationized through a reaction in an aqueous alkaline medium with 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). The chemical modification of xylan was confirmed by using 1H-13C HSQC (Heteronuclear Single Quantum Coherence) NMR, and was quantified by using elemental analysis. The GAX cationization, which introduced cationic charge densities ranging from 110 to 740 μeq/g, was shown to increase the rate and magnitude of adsorption extensively, due to the induced electrostatic interaction between the anionic fibres and the cationic xylan. Similar to non-modified xylan, cationic xylan possessed a non-electrostatic cellulose surface affinity, as shown by adsorption at high ionic-strength and on esterified (carboxyl-free) pulp fibres.

Presence of 1→3-linked 2-O-β-d-xylopyranosyl-α-l-arabinofuranosyl side chains in cereal arabinoxylans

The presence of a fairly uncommon side chain 2-O-β-d-xylopyranosyl-α-l-arabinofuranosyl in arabinoxylans (AX) from eight different cereal by-products was investigated, using 1H NMR spectroscopy and high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) after Shearzyme® (GH10 endo-1,4-β-d-xylanase) hydrolysis. This disaccharide side group was present in significant amounts in AX extracted from corn cobs and barley husks. For the first time, it was also detected in AX from oat spelts and rice husks, and in lesser amounts in wheat straw AX. Arabinoxylo-oligosaccharide (AXOS) containing the 2-O-β-d-Xylp-α-l-Araf side chain was purified from the oat spelt AX hydrolysate and the structure was fully analyzed using 1D and 2D NMR spectroscopy. The AXOS was identified as β-d-Xylp-(1→2)-α-l-Araf-(1→3)-β-d-Xylp-(1→4)-d-Xyl. To our knowledge, such a structure with 2-O-β-d-Xylp-α-l-Araf attached to the O-3 of the nonreducing end of xylobiose has not been described previously. New information on substitution of AX from various cereal by-products was obtained by combining NMR and enzyme-assisted HPAEC-PAD analysis.

Fractionation of industrial solids containing barley husks in aqueous media

Lignocellulosic materials, particularly the ones of residual nature generated in agricultural and industrial activities, represent a renewable, abundant and cheap source of raw materials for multiple purposes. Barley husks belong to this type of materials. Aqueous fractionation of a solid byproduct from malting industries (denoted MSW), mainly made up of barley husks, leads to a liquid phase containing bioactive components (oligosaccharides derived from hemicelluloses with prebiotic activity and low molecular weight phenolics with antioxidant activity) and to a solid phase containing cellulose and lignin as major components. Antioxidant compounds can be separated from fractionation liquors by physicochemical processing, providing a practical approach to sustainable development. Based on experimental data, the solubilization of MSW hemicelluloses is assessed in terms of kinetics, composition, material balances and properties of the isolated fractions. The nature, refining and properties of the antioxidant compounds extracted from liquors obtained by non-isothermal processing of MSW are discussed on the basis of experimental results.

Improvement of arabinoxylan isolation from barley husks

A method of extracting arabinoxylan from barley husks has previously been developed, but was found to suffer from three problems, namely: starch was dispersed in the aqueous phase during steam pretreatment, the yield of extracted arabinoxylan with high molecular mass was low in the steam pretreatment step, and there was high filtration resistance in the clarification step. This paper presents possible solutions to these problems. Starch was removed prior to steam pretreatment by boiling the husks in water for 1 h. This treatment decreased the content of glucan in the aqueous phase after steam pretreatment by 75%. The yield of arabinoxylan with a molecular mass greater than 5 kDa was increased from 5% to 25% by using alkaline impregnation (1 wt.% NaOH). A vibrating shear-enhanced microfiltration unit was proven to be an alternative method to traditional filtration for clarification of the aqueous phase.

Fractionation of Antioxidants from Autohydrolysis of Barley Husks

The liquid phase from nonisothermal autohydrolysis of barley husks was extracted with ethyl acetate and redissolved in ethanol to yield a crude extract (denoted BHEAE), which was subjected to further processing to enhance the antioxidant activity. A fractionation method, carried out for characterization purposes, consisted of the extraction of BHEAE with organic solvents of increasing polarity and further fractionation in Sephadex LH-20. Among the tested solvents, ethyl acetate allowed the highest yield, phenolic content, and antioxidant activity. Upon elution with methanol, products with high DPPH radical scavenging capacity (IC50 = 0.22 g/L) were obtained. The major compounds in the isolate were benzoic and cinnamic acids. Adsorption-desorption in commercial polymeric resins was carried out as an alternative strategy for BHEAE refining. This method is more suited for possible scale-up and provided a concentrate with a Trolox equivalent antioxidant capacity of 9 mM, which was obtained at a yield of 18 g/kg of barley husks.

Extraction of water-soluble hemicelluloses from barley husks

Heat treatment of barley husks was performed to extract arabinoxylan with high yield and high weight-averaged molecular mass (MW). Microwave irradiation was employed for initial screening of suitable residence times (2–15min), temperatures (120–210°C) and initial pH (3–13) of the reaction slurry. Microwave irradiation was shown to be a good method for predicting the effects of heat treatment on a larger scale using steam pretreatment. A MW of about 40,000Da was achieved without the addition of chemicals, by both microwave irradiation and steam pretreatment, with a yield of about 9%. The yield was significantly increased by slightly increasing the severity factor. However, the MW decreased below 20,000Da at severity factors above 3.7. Arabinosyl side groups were enzymatically hydrolysed from the arabinoxylan by α-l-arabinofuranosidase to a degree of 47%, demonstrating the ability to specifically alter the side group substitution of arabinoxylans with the use of enzymes.

Structural Comparison of Arabinoxylans from Two Barley Side-Stream Fractions

The structures of barley ( Hordeum vulgare) arabinoxylans isolated from two industrial side fractions, barley husks (BH) and barley fiber (BF), were characterized. Arabinoxylans were extracted with saturated barium hydroxide after enzymatic pretreatment. Barium hydroxide was selective toward arabinoxylans, and only a minor amount of glucose-containing material was coextracted. Acid methanolysis followed by gas chromatography, 1H NMR spectroscopy, and specific enzymatic treatments followed by anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) revealed that the chemical structure of barley husk arabinoxylan (BHAX) clearly differed from that of barley fiber arabinoxylan (BFAX). BFAX was more branched, containing more beta-D-xylopyranosyl (beta-D-Xylp) residues carrying alpha-L-arabinofuranosyl (alpha-L-Araf) units at both O-2 and O-3 positions. BHAX, on the other hand, contained more 2-O-beta-D-Xyl p-alpha-L-Ara f substituents than BFAX. BHAX and BFAX also differed with respect to the hydrodynamic properties investigated with multidetector size exclusion chromatography. BFAX had a higher weight-average molar mass and larger hydrodynamic volume, the latter indicating less dense conformation than BHAX. Mn, Mw /Mn, Rh, and the Mark-Houwink a value were also determined for both arabinoxylans.

Remediation of Textile Dye Waste Water Using a White-Rot Fungus Bjerkandera adusta Through Solid-state Fermentation (SSF)

A strict screening strategy for microorganism selection was followed employing a number of white-rot fungi for the bioremediation of textile effluent, which was generated from one Ireland-based American textile industry. Finally, one fungus Bjerkandera adusta has been investigated in depth for its ability to simultaneously degrade and enrich the nutritional quality of highly coloured textile effluent-adsorbed barley husks through solid-state fermentation (SSF). Certain important parameters such as media requirements, moisture content, protein/biomass production and enzyme activities were examined in detail. A previously optimised method of dye desorption was employed to measure the extent of dye remediation through effluent decolorisation achieved as a result of fungal activity in SSF. B. adusta was capable of decolourising a considerable concentration of the synthetic dye effluent (up to 53%) with a moisture content of 80-85%. Protein enrichment of the fermented mass was achieved to the extent of 229 g/kg dry weight initial substrate used. Lignin peroxidase and laccase were found to be the two main enzymes produced during SSF of the dye-adsorbed lignocellulosic waste residue.

The effect of barley husk arabinoxylan adsorption on the properties of cellulose fibres

This study investigates the adsorption of (glucurono)arabinoxylan (GAX) on cellulose fibres and the properties thereof. A water-soluble GAX, from barley husks (Hordeum vulgare), was isolated using chlorite delignification and alkaline extraction followed by enzymatic purification. The isolated GAX fraction showed an arabinose to xylose ratio of 0.22 and a weight average molar mass of 20,200 g/mol, as determined by size exclusion chromatography (SEC) in DMSO:H2O. The GAX was adsorbed on cellulose fibres under well controlled conditions, where temperature and initial concentration of GAX proved to be important parameters in controlling the level of adsorption. The adsorption process was also dependent on xylan molecular structure. Carbohydrate analysis on the modified fibres showed a preferential adsorption of low substituted xylans (arabinose to xylose ratio of ∼0.10). During the adsorption process the GAX solution was analyzed using SEC-RI-MALLS in aqueous solvent, which demonstrated a molecular xylan adsorption on cellulose fibres. Additionally, a decrease in light scattering responses, which corresponds to an adsorption of aggregated xylan and/or xylan with a great tendency towards self-association, could be observed during the adsorption process. This was demonstrated by adsorption of GAX on regenerated cellulose fibres (Lyocell), which compared to native fibres possesses a relatively smooth fibre surface. Atomic force microscopy analysis visualised a heterogeneous decoration of the Lyocell fibres with xylan agglomerates. The effect of GAX adsorption on paper strength was also investigated. A GAX modified kraft pulp showed an evident increase in tensile strength, which might be due to a retained fibre–fibre bonding ability for xylan coated fibrils after drying and rewetting.

Isolation of hemicelluloses from barley husks

In this work, arabinoxylan, the primary hemicellulose in barley husks, was isolated from barley husks by steam explosion and ultrafiltration. Ultrafiltration and diafiltration were used to concentrate and to increase the purity of the product which was intended for use as an oxygen barrier film in food packaging. A composite fluoropolymer membrane with a nominal molecular mass cut-off of 10,000 g/mol was used during ultrafiltration and diafiltration. The average flux during ultrafiltration to a volume reduction of 0.85 was 90 L/m 2 h. The flux was approximately constant (50 L/m 2 h) during diafiltration. Polysaccharides constituted about 40% of the solids fraction before ultrafiltration and nearly 70% after diafiltration. Arabinoxylan made up 45% of the polysaccharide fraction after diafiltration.

Non-isothermal autohydrolysis of barley husks: Product distribution and antioxidant activity of ethyl acetate soluble fractions

Non-isothermal treatments of barley husks in aqueous media were performed under a variety of operational conditions, to cause the hydrolytic degradation of hemicelluloses. The amount and composition of solid and liquid phases were determined. Liquors from treatments were extracted with ethyl acetate in order to remove non-saccharide components (mainly derived from the extractive acid-soluble lignin fractions), and the extracted fractions were quantified and assayed for antioxidant activity using the DPPH radical scavenging test. Posthydrolysis of autohydrolysis liquors led to xylose-containing solutions suitable as fermentation media. The dependence of the major process parameters (concentrations of monosaccharides and monosaccharide-degradation products obtained after autohydrolysis–posthydrolysis, yield of ethyl acetate soluble compounds and antioxidant activity of isolates) on the severity of treatments was assessed. The ethyl acetate soluble fraction obtained under the best processing conditions showed an antioxidant activity in the range reported for synthetic antioxidants.

Integral utilisation of barley husk for the production of food additives

AbstractA new and effective chemical–biotechnological process for the global utilisation of barley husk (obtained from the spent grains in the brewing process) is reported. With the proposed process the three main components of the lignocellulosic residue (cellulose, hemicellulose and lignin) are utilised. A first treatment with sulfuric acid (pre‐hydrolysis) allowed the solubilisation of hemicelluloses to give xylose and glucose‐containing liquors (suitable to make fermentation media for the continuous lactic acid (LA) production with L. pentosus) and a solid phase containing cellulose and lignin. In this set of experiments, a maximum volumetric productivity (QP) = 2.077 g L−1 h−1 and product yield (YP/S) = 0.62 g g−1 were obtained for a dilution rate of 0.01 h−1. The solid residues from pre‐hydrolysis were treated with NaOH in order to increase their cellulase digestibility, and dissolve the lignin content. The cellulose residue was used as substrates for lactic acid production by simultaneous saccharification and fermentation (SSF) in media containing Trichoderma reesei cellulases and Lactobacillus rhamnosus cells using the complete MRS broth or a cheaper medium. In both cases similar LA concentrations and volumetric productivities were achieved (P = 73.4–71.0 g L−1 and QP = 1.28–1.25 g L−1 h−1, respectively), where P is LA concentration. The lignin solution obtained after the alkaline treatment was extracted with ethyl acetate in order to obtain the phenolic components. The extract obtained at pH 3 showed three times more antioxidant activity than the one extracted at pH 12.8, with an EC50 of 1.396 g L−1 for pH 3 and 4.604 g L−1 for pH 12.8. The best extracts showed twice antioxidant activity than BHT. Copyright © 2007 Society of Chemical Industry

Evidence of the presence of 2- O-β- d-xylopyranosyl-α- l-arabinofuranose side chains in barley husk arabinoxylan

(Glucurono)arabinoxylans were extracted from barley husks and degraded with endo-β-xylanase or subjected to periodate oxidation. The released oligosaccharide fragments were separated and isolated on Biogel-P2, and their structures were determined by NMR spectroscopy. The oligosaccharides identified consisted of β- d-(1→4)-linked xylopyranosyl residues, of which some were substituted at O-3 with α- l-arabinofuranosyl groups or at O-2 with 4- O-methylglucuronic acid. In addition to these substituents, a disaccharide side chain, 2- O-β- d-xylopyranosyl-α- l-arabinofuranose, attached at position O-3 of the main chain, was proved to exist in arabinoxylan from barley husks. The compound was fully characterized with NMR, and all 1H and 13C NMR signals were assigned. The arabinose to xylose ratio was low (∼0.2) and no 2,3-disubstitution existed. No blocks of substituted xylose residues could be observed along the main chain.

Electron seed dressing of barley—aspects of its verification

Seeds (e.g. cereal grains) are treated with low energy electrons for seed dressing to inactivate phytopathogenic organisms on their surface and in the seed coat. To verify the electron treatment of barley by e-ventus® technology, three physical detection methods were investigated: photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR). Influencing factors such as storage time and temperature, geographic origin of samples and light exposure were studied. All three detection methods proved to be suitable, with PSL being the most convenient. But also ESR by measuring the barley husks offered a simple and rapid verification. Although TL was more laborious to perform, it was highly reliable. PSL was able to classify electronically dressed seeds after storage times of at least 12–13 months independent of storage temperatures, assayed in the range of 5–23 °C. The applicability of ESR after storage was dependent on the measuring system used and on storage temperature. At room temperature the advanced E-Scan™ spectrometer allowed verification of treatment for at least 7.5 months, whereas the EMS 104 spectrometer was applicable only up to 2 months of storage. Storage temperatures of 5 °C markedly prolonged the verifiability of treatment. Using TL, treated samples stored at room temperature could be easily verified for at least 13 months. Fading of the PSL signal of treated barley was observed under the influence of light, the extent of fading being influenced by illuminance but not by treatment of the samples with high or low energy electrons. Contrary to PSL, TL and ESR were found to be still applicable for the detection of treated barley exposed to light.