Arabinoxylan Films Research Articles

Improving Biodegradable Films from Corn Bran Arabinoxylan for Hydrophobic Material and Green Food Packaging.

Non-biodegradable plastic materials pose environmental hazards and contribute to pollution. Arabinoxylan (AX) films have been created for applications in food packaging to replace these materials. The water interaction characteristics of biodegradable AX films were assessed following the extraction of AX from dry-milled corn bran (DCB), wet-milled corn bran (WCB), and dried distiller's grains with solubles (DDGS). Films were prepared with laccase and sorbitol before surface modification with lipase-vinyl acetate. Water solubility of the modified DCB films was significantly reduced (p < 0.05); however, the water solubility of modified WCB films decreased insignificantly (p > 0.05) compared to unmodified films. Water vapor permeability of the modified AX films from WCB and DDGS was significantly reduced (p < 0.05), unlike their unmodified counterparts. The biodegradation rates of the modified WCB AX and DDGS films increased after 63 and 99 days, respectively, compared to the unmodified films. The hydrophilic nature of AX polymers from WCB and DDGS enhances the biodegradability of the films. This study found that the modified WCB AX film was more hydrophobic, and the modified DDGS AX film was more biodegradable than the modified DCB AX film. Overall, surface modifications have potential for improving hydrophobicity of biopolymer films.

Enhancing Mechanical Properties of Corn Bran Arabinoxylan Films for Sustainable Food Packaging.

Arabinoxylan (AX)-based films can improve the mechanical characteristics of biodegradable materials when utilized for food packaging. However, the mechanical properties of AX films for food packaging applications require thorough investigation to establish their viability. In this study, AX was extracted from corn bran coproducts of dry-milling (DCB), wet-milling (WCB), and dried distiller's grains with solubles (DDGS) using an acid-alkali method. Packaging materials were produced using these AX extracts, each combined with laccase and sorbitol, forming the basis for three different films. These films were then modified by immersing the surface in a lipase-acetate solution. We evaluated their mechanical characteristics, including thickness, tensile properties, tear resistance, and puncture resistance. The thickness and tensile properties of the modified AX films derived from DCB and DDGS showed significant improvements (p < 0.05) compared to the unmodified AX films. In contrast, the modified AX films from WCB showed no significant changes (p > 0.05) in thickness and tensile properties compared to the unmodified WCB AX films. A significant increase in tear resistance (p < 0.05) was observed in all modified AX films after immersion in the lipase-acetate mixture. While puncture resistance was enhanced in the modified AX films, the improvement was not statistically significant (p > 0.05) compared to the unmodified films. The presence of hydroxyl (OH) and carbonyl (CO) groups on the surfaces of AX films from DCB and DDGS, modified by the lipase-acetate solution, suggests excellent biodegradability properties. The modification process positively affected the AX films, rendering them more bendable, flexible, and resistant to deformation when stretched, compared to the unmodified AX films.

Development and Characterisation of Arabinoxylan-Based Composite Films

In the last decades, the overuse of synthetic polymers in the packaging industry has become a serious global environmental problem due to their nonbiodegradability. To overcome this issue, attention has been driven to study alternative materials, namely the use of biodegradable biopolymers extracted from agro-industrial residues, as materials for food packages. In this work, the polysaccharide arabinoxylan, previously extracted from corn fibre by alkaline hydrolysis, was used to produce composite and multilayer films. The composite films were produced by casting an oil-in-water emulsion with different quantities of oleic acid, while the multilayer films (beeswax-arabinoxylan-beeswax) were manufactured by submerging the arabinoxylan films in a beeswax solution. Both film types, along with a film composed only of arabinoxylan, were characterised in terms of their antioxidant activity, optical and mechanical properties, surface hydrophobicity, and barrier properties against water vapour (WVP), gases, and ultraviolet-visible (UV-vis) radiation. All the films developed were soluble in water. The multilayer films were more advantageous than the emulsion-based ones due to their enhanced barrier properties against water vapour (WVP = 0.58 × 10−11 mol/m∙s∙Pa), oxygen (with a permeability of 3.28 × 10−12 mol·m−1·s−1·Pa−1) and UV-vis radiation and higher values of water contact angle (92.43°), tensile stress (4.11 MPa), and Young’s modulus (15.96 MPa). The films developed, especially the multilayer ones, showed a good potential to produce flexible packages for low-water-content food products (e.g., several types of nuts).

Effect of cellulose and starch fatty acid esters addition on microstructure and physical properties of arabinoxylan films

Arabinoxylan (AX) and cellulose were extracted from wheat straw, whereas starch was extracted from potato peel. Thereafter, cellulose and starch were esterified with lauric, myristic, palmitic and stearic acids to prepare corresponding cellulose (CFAs) and starch fatty acid esters (SFAs) with DS 2.1–2.8. XRD study revealed remarkable loss of crystallinity in cellulose and starch due to fatty acid esterification. The addition of palmitate and stearate esters of cellulose and starch to AX formed laminar film microstructures which limited water vapor permeability whereas films prepared by blending AX with laurate and myristate esters of starch and cellulose were less effective as water vapor barrier due to their non-layer microstructures. The laminar structures also resulted significant reduction in mechanical strength of the composite films. Furthermore, all AX-CFAs and AX-SFAs films were thermally more stable than native composite films. These films might be used to produce industrially useful coating material for food products.

Bio-based films from wheat bran feruloylated arabinoxylan: Effect of extraction technique, acetylation and feruloylation

This study demonstrates the potential of feruloylated arabinoxylan (AX) from wheat bran for the preparation of bioactive barrier films with antioxidant properties. We have comprehensively evaluated the influence of the structural features and chemical acetylation of feruloylated AX extracted by subcritical water on their film properties, in comparison with alkaline extracted AX and a reference wheat endosperm AX. The degree of substitution (DS) of AX had a large influence on film formation, higher DS yielded better thermal and mechanical properties. The barrier properties of AX films were significantly enhanced by external plasticization by sorbitol. Chemical acetylation significantly improved the thermal stability but not the mechanical or barrier properties of the films. The presence of bound ferulic acid in feruloylated AX films resulted in higher antioxidant activity compared to external addition of free ferulic acid, which demonstrates their potential use in active packaging applications for the preservation of oxygen-sensitive foodstuff.

How Do Arabinoxylan Films Interact with Water and Soil?

Biodegradable materials made from cereal arabinoxylan could provide an alternative source of packaging to replace current nonbiodegradable plastics. The main purpose of this research was to determine how arabinoxylan (AX) films made from wheat bran (WB) AX, maize bran (MB) AX, and dried distillers grain (DDG) AX made with either glycerol or sorbitol at varying levels (10, 25 or 50%) interacts with soil and water. The biodegradability of all films ranged from 49.4% biodegradable (DDG AX with 10% sorbitol) to 67.7% biodegradable (MB AX with 50% glycerol). In addition, the MB AX films with 25% sorbitol had the lowest moisture content at 9.7%, the MB AX films with 10% glycerol had the highest water solubility at 95.6%, and the MB AX films with 50% glycerol had the highest water vapor transmission rate (WVTR) at 90.8 g h−1 m−2. Despite these extreme trends in the MB AX films, the WB AX films were the least hydrophilic on average while the DDG AX films were the most hydrophilic on average. The 18 materials developed in this research demonstrate varying affinities for water and biodegradation. These materials can be used for many different packaging materials, based on their unique characteristics.

Evaluation of arabinoxylan isolated from sorghum bran, biomass, and bagasse for film formation

Arabinoxylans (AX) are potential agricultural co-products for material applications. Sorghum has seen increased production as a bioenergy crop for biofuel and co-product generation. AX from three sorghum fractions (bran, bagasse, and biomass) were isolated to study film formation. All three AX fractions exhibited high moisture sensitivity. Sorghum biomass AX produced low water vapor permeability compared to sorghum bran or sorghum bagasse AX films. Glycerol addition to sorghum bran AX films reduced tensile strength from 34.8 to 16.0 MPa at 0% and 10% (w/w) glycerol, respectively; reduced the storage and loss moduli during dynamic mechanical analyses at 50% relative humidity (RH) and decreased the rubber-to-plastic material transition temperature at 50% RH, from 78.1 °C to 38.4 °C at 0 and 10% (w/w) glycerol, respectively. Sorghum bran AX, while sensitive to water absorption at high RH, produced favorable strength performance compared to AX from other cereal grains indicating potential utilization as a renewable material.

Mechanical profiles and topographical properties of films made from alkaline extracted arabinoxylans from wheat bran, maize bran, or dried distillers grain

Cereal processing byproducts including wheat (Triticum aestivum L.) bran, maize (Zea mays L.) bran, and dried distillers grain are currently utilized in animal feed, but they could be utilized in value-added products such as food packaging materials. This study determined the topographical properties and mechanical profiles of films made from arabinoxylan extracts of wheat bran, maize bran, and dried distillers grain with the addition of either glycerol or sorbitol as a plasticizing agent at one of three levels (10, 25, or 50%). The arabinoxylan was extracted from these starting materials via alkaline extraction and purified using α-amylase, protease, and dialysis. Film properties analyzed included surface topography, puncture resistance, tensile strength, and tear resistance. Topographical analysis showed that the films made with wheat bran arabinoxylan were the roughest. The puncture resistances ranged from 0.7 N (dried distillers grain arabinoxylan films plasticized by 10% sorbitol) to 10.1 N (wheat bran arabinoxylan films plasticized by 50% sorbitol). The highest maximum tensile strength was 29.3 MPa for films made with maize bran arabinoxylan plasticized by 10% glycerol. In addition, these arabinoxylan films had tear resistances ranging from 0.3 N (maize bran arabinoxylan films plasticized by 50% glycerol) to 1.9 N (wheat bran arabinoxylan films plasticized by 50% sorbitol). These material profiles provide information about the strengths and weaknesses of 18 novel materials that could serve as food packaging materials in the future.

Effect of β-glucan-fatty acid esters on microstructure and physical properties of wheat straw arabinoxylan films

Arabinoxylans (AX) was isolated from wheat straw, whereas β-glucan (BG) was extracted from oat flour. The compositional analysis indicated wheat straw AX contained arabinose and xylose as major constituent sugars whereas higher β-glucan content (77%) was found in the extracted material from oat flour. The BG was conjugated with lauric (LA), myristic (MA), palmitic (PA), stearic (SA) and oleic (OA) acid to prepare corresponding β-glucan-fatty acid esters (BGFAs) with nearly similar degree of substitution. The effect of BGFAs to AX films on the water barrier, optical and mechanical properties were investigated. The addition of LABG and MABG to AX formed laminar structures in the composite films which limited water vapor permeability, giving rise to more opacity. Films prepared by blending AX with SABG and OABG were less effective as water vapor barrier due to their non-layer film microstructures; however they were less opaque. The laminar structures also imparted less mechanical strength and flexibility in the composite films. Furthermore, thermogravimetric analysis (TGA) revealed that all AX-BGFAs composite films were thermally more stable than pure AX and AX-BG films.

Glutaraldehyde crosslinking of arabinoxylan produced from corn ethanol residuals

This study investigated the possibility of substituting petroleum-based polymers with biopolymers for films and paper coatings. Arabinoxylan (AX) was extracted from distillers’ grains, a low-value corn ethanol byproduct, and modified through crosslinking with glutaraldehyde (GA) which was made into films and paper coatings. The effects of degree of substitution (DS) on film and coating properties of GA cross-linked AX, referred to as GAX, were investigated. The GAX films had markedly higher tensile strength, approximately 3 times higher than the unmodified AX films at low DS, with higher DS causing a negative effect on the film tensile strength. Compared to unmodified AX coating, paper coated with GAX also had significantly higher tensile index, presumably due to high adhesion between the coating and paper interface. When used as a coating binder with calcium carbonate pigments, GAX showed comparable performance to polyvinyl alcohol, a common industrial binder, demonstrating the potential to be substituted for the petroleum-based paper coating binder.

Covalently Cross-Linked Arabinoxylans Films for Debaryomyces hansenii Entrapment.

In the present study, wheat water extractable arabinoxylans (WEAX) were isolated and characterized, and their capability to form covalently cross-linked films in presence of Debaryomyces hansenii was evaluated. WEAX presented an arabinose to xylose ratio of 0.60, a ferulic acid and diferulic acid content of 2.1 and 0.04 µg∙mg−1 WEAX, respectively and a Fourier Transform Infra-Red (FT-IR) spectrum typical of WEAX. The intrinsic viscosity and viscosimetric molecular weight values for WEAX were 3.6 dL∙g−1 and 440 kDa, respectively. The gelation of WEAX (1% w/v) with and without D. hansenii (1 × 107 CFU∙cm−2) was rheologically investigated by small amplitude oscillatory shear. The entrapment of D. hansenii decreased gel elasticity from 1.4 to 0.3 Pa, probably by affecting the physical interactions between WEAX chains. Covalently cross-linked WEAX films containing D. hansenii were prepared by casting. Scanning electron microscopy images show that WEAX films containing D. hansenii were porous and consisted of granular-like and fibre microstructures. Average tensile strength, elongation at break and Young’s modulus values dropped when D. hansenii was present in the film. Covalently cross-lined WEAX containing D. hansenii could be a suitable as a functional entrapping film.

Influence of carboxymethylation on the surface physical–chemical properties of glucuronoxylan and arabinoxylan films

Xylans were carboxymethylated in order to increase their anionic nature and thus tune their surface free energy (SFE) and hydrophilicity, which are of crucial importance in the majority of special applications. Fourier transform infrared spectroscopy and polyelectrolyte titration results confirmed the successful carboxymethylation of the xylan samples. The main aim of this study was to investigate the influences of carboxymethylation of glucuronoxylan and arabinoxylans on the surface physical and chemical properties of the films made from them. Films were prepared by the casting method, and their surface morphologies were analyzed by atomic force microscopy. The surface chemical compositions of the films were investigated using X‐ray photoelectron spectroscopy, and their influences on SFE, i.e., Lifshitz–van der Waals and electron donor and acceptor contributions, were determined using goniometry. The introduction of ∼2 mmol/g of carboxyl groups into the glucuronoxylan or arabinoxylan molecular structures had a significant influence on the chemical and physical surface properties of the prepared films. Higher amounts of the carboxyl group present on the films' surfaces and higher surface roughness contributed to a significant increase (by 270%) in the electron donor component of SFE and to 40% improvements in the hydrophilicities of the films' surfaces. POLYM. ENG. SCI., 55:2706–2713, 2015. © 2015 Society of Plastics Engineers

Nanofibrillated cellulose reinforced acetylated arabinoxylan films

In this study, acetylated rye arabinoxylan (AcAX) films were reinforced with nanofibrillated cellulose from spruce (NFC) ranging from 1 to 10 wt% of the total composition. Free-standing composite films were casted without the use of any plasticizers. The homogeneous dispersion of NFC in the films was confirmed with scanning electron microscopy. The ultimate strength and the Young’s modulus determined by tensile tests increased from 65 MPa and 2190 MPa for neat AcAX films to 93 MPa and 3360 MPa for the 10% composite films, respectively. The elongation to break of the 10% NFC composite film was a remarkable 10.5%. The moisture absorbed was still less than 8 wt% for the films with 10% NFC content at 97% relative humidity at room temperature, which is low for hemicellulose-based films. The addition of NFC decreased the water permeability of the films at low NFC contents, which was studied in diffusion cells using radioactive labeled water. Thus NFC can be used in an unmodified form as reinforcement in AcAX films to prepare films or coatings that are more water and humidity resistant than neat hemicellulose-based films.

Lipases efficiently stearate and cutinases acetylate the surface of arabinoxylan films

This is the first report on successful enzyme catalyzed surface esterification of hemicellulose films. Enzyme catalyzed surface acetylation with vinyl acetate and stearation with vinyl stearate were studied on rye arabinoxylan (AX) films. Different surface analytical techniques (FT-IR, TOF-SIMS, ESCA, CA) show that lipases from Mucor javanicus, Rhizopus oryzae and Candida rugosa successfully surface stearate AX films and that a cutinase from Fusarium solani pisi surface acetylates these films. The specificities of cutinase and lipases were also compared, and higher activity was observed for lipases utilizing long alkyl chain substrates while higher activity was observed for cutinase utilizing shorter alkyl chain substrates. The contact angle analysis showed films with increased initial hydrophobicity on the surfaces.

Hydration and mechanical properties of arabinoxylans and β-d-glucans films

Arabinoxylans (AX) and (1→3)(1→4)-β-d-glucans (BG) are the main components of the cell walls in the endosperm of wheat grain. The relative occurrence of these two polysaccharides and the fine structure of the AX are highly variable within the endosperm. Films of AX and BG were used as models of the cell wall to study the impact of polymer structure on the hydration and mechanical properties of the cell walls. Effective moisture diffusivities (Deff) of AX and BG films were determined from 0 to 95% relative humidity (RH) at 20°C. Deff was influenced by the water content, and the structure of polysaccharides. Higher Deff was obtained for films made with highly substituted AX compared to values obtained for films made with BG or lowly substituted AX. Proton dipolar second moments M2 and water T2 relaxation times measured by TD-NMR, indicated that the highly branched AX films exhibited a higher nano-porosity, favoring water motions within films. Results from traction tests showed significant different mechanical properties between the AX and BG films. BG films exhibited much higher extensibility than AX films. Strength and extensibility of AX films decreased with increasing arabinose to xylose ratio. Our results show that the water motions and the mechanical properties of AX and BG films can be linked to the polysaccharide chains interactions that modulate the nanostructure of films.

Composite Films of Arabinoxylan and Fibrous Sepiolite: Morphological, Mechanical, and Barrier Properties

Hemicelluloses represent a largely unutilized resource for future bioderived films in packaging and other applications. However, improvement of film properties is needed in order to transfer this potential into reality. In this context, sepiolite, a fibrous clay, was investigated as an additive to enhance the properties of rye flour arabinoxylan. Composite films cast from arabinoxylan solutions and sepiolite suspensions in water were transparent or semitransparent at additive loadings in the 2.5-10 wt % range. Scanning electron microscopy showed that the sepiolite was well dispersed in the arabinoxylan films and sepiolite fiber aggregation was not found. FT-IR spectroscopy provided some evidence for hydrogen bonding between sepiolite and arabinoxylan. Consistent with these findings, mechanical testing showed increases in film stiffness and strength with sepiolite addition and the effect of poly(ethylene glycol) methyl ether (mPEG) plasticizer addition. Incorporation of sepiolite did not significantly influence the thermal degradation or the gas barrier properties of arabinoxylan films, which is likely a consequence of sepiolite fiber morphology. In summary, sepiolite was shown to have potential as an additive to obtain stronger hemicellulose films although other approaches, possibly in combination with the use of sepiolite, would be needed if enhanced film barrier properties are required for specific applications.

Arabinoxylan/nanofibrillated cellulose composite films

There is an increasing interest in substituting petroleum based polymer films, for food packaging applications, with films based on renewable resources. In many of these applications, low oxygen permeability and low moisture uptake of films are required, as well as high enough strength and flexibility. For this purpose, rye arabinoxylan films reinforced with nanofibrillated cellulose was prepared and evaluated. A thorough mixing of the components resulted in uniform films. Mechanical, thermal, structural, moisture sorption and oxygen barrier characteristics of such films are reported here. Reinforcement of arabinoxylan with nanofibrillated cellulose affected the properties of the films positively. A decrease in moisture sorption of the films, as well as an increase in stiffness, strength and flexibility of the films were shown. From these results and dynamic FTIR spectra, a strong coupling between reinforcing cellulose and arabinoxylan matrix was concluded. Oxygen barrier properties were equal or better as compared to the neat rye arabinoxylan film. In general, the high nanofibrillated cellulose containing composite film, i.e. 75 % NFC, showed the best properties.

Extraction and chemical characterization of rye arabinoxylan and the effect of β-glucan on the mechanical and barrier properties of cast arabinoxylan films

Water-extractable hemicellulose (WEH) fractions, containing approximately 65% arabinoxylans (WE-AX) and 20% mixed-linkage β-glucans were isolated from rye bran. In addition, water-extractable mixed-linkage β-glucans (BG) were isolated from oat bran as a reference material. The β-glucan content of the rye hemicellulose isolate was reduced to less than 5% by a selective lichenase treatment. Rye hemicelluloses, WEH and WE-AX had arabinose-to-xylose ratios of 0.54 and 0.57 and weight-average molecular weights (Mw) of 270 000 and 232 000 g/mol respectively. The Mw of BG was higher at 386 000 g/mol. The material properties of films prepared from the rye hemicellulose isolate and WE-AX as such, or with varying amounts of added BG (20:80; 50:50; 80:20 ratios) were studied. Prior removal of β-glucan from the isolate decreased the tensile strength of the films significantly as well as the elongation at break. Addition of BG to the purified WE-AX resulted in an increase in the tensile strength and elongation at break of the films. In contrast, the presence of BG had no clear effect on the oxygen permeability of the films. Both pure rye WE-AX and pure BG films showed excellent oxygen barrier properties (between 0.9 and 1.0 cm3 μm/m2 d kPa). However, the water vapor permeability increased with addition of increasing amounts of BG to WE-AX. To our knowledge, this is the first study on the effect of β-glucans on the material and permeability properties of arabinoxylan-based films.

Arabinose content of arabinoxylans contributes to flexibility of acetylated arabinoxylan films

AbstractArabinoxylans (AX) from rye were partly debranched by chemical hydrolysis methods, and AXs differing in arabinosyl substitution were acetylated using chemical methods. The resulting materials are film forming, and these films underwent molecular structural analysis and were tested for their material properties. The composition and structure of the modified polymers were determined using high performance anion exchange chromatography and two dimensional nuclear magnetic resonance; it was shown that all free hydroxyl groups (of both xylose and arabinose) were acetylated. Further characterizations were done by dynamic mechanical analysis and thermo‐gravimetric analysis to evaluate the thermal behavior of the material. The observed glass transition temperatures (Tg) increased with a decrease in arabinosyl substitutions. The thermal degradation temperatures were all close to 380°C. The mechanical properties were characterized with tensile tests of the films. Tensile tests showed that the strain at break, which reflects the flexibility of the material, was significantly higher at higher arabinosyl substitution levels. The elastic Young's modulus was not significantly affected, although a tendency was seen toward a less stiff material at higher arabinosyl substitution. The ultimate strength of the materials was remarkably high in all cases, around 60 MPa, with little difference between them. Considering these properties, a great potential is foreseen in the application of acetylated arabinoxylans as packaging films and as matrix for composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Extraction of Hemicelluloses from Corn Pericarp by the NaOH-Urea Solvent System

The NaOH-urea solvent system was applied for solubilization of hemicelluloses in corn pericarp (CP), an industrial waste of corn starch production, and the mechanical properties of films prepared from the isolated hemicelluloses were analyzed. CP was soaked in 0-8 wt% NaOH solutions containing 0-8M urea, and the mixtures were frozen at -20°C and thawed. By a simple recovery of the thawed solutions by filtration hemicelluloses were found to be solubilized efficiently above 2 wt% NaOH. The results of sugar compositional analysis indicate that the extracted materials were mixtures of hemicelluloses composed of arabinoxylan and β-(1,3;1,4)-glucan having arabinose/xylose ratios of 0.84-0.72. The present results indicated that NaOH solutions containing urea, with concentrations not enough to solubilize cellulose were adequate for extraction of hemicelluloses in CP. The hemicellulose extracted with 2 wt% NaOH-6M urea could form transparent films whose mechanical properties were 56.2MPa, 3.5% and 3.09GPa for breaking stress (σmax), maximum strain (ɛmax) and elastic modulus (E), respectively, as evaluated by tensile tests. These values were 1.2-, 1.3- and 0.94-fold higher than those obtained by the film of arabinoxylan alone. Results suggest that β-glucan gives mechanical strength and flexibility to the stiff arabinoxylan films.