Crystal Structure Of Cellulose Research Articles

A hybrid electrocoagulation-biocomposite adsorption system for the decolourization of dye wastewater

Among the various methods for the removal of azo dye, electrocoagulation is recognized to be highly efficient. However, the process is associated with high operation and maintenance cost, which demands the need for reducing the electrolysis time without compromising the performance efficiency. This can be achieved by adopting hybrid electrocoagulation process with a low-cost but effective process, such as adsorption. The study investigated the performance of a hybrid electrocoagulation-biocomposite system (H-EC-BC) for removing methyl orange dye. Firstly, the operating parameters of electrocoagulation process were optimized and a removal efficiency of 99% has been attained using Fe-SS electrodes at a pH of 6 for a reaction time of 30 min. The performance of EC process was found to be decreasing with increase in dye concentration. Secondly, biocomposite was synthesized from Psidium guajava leaves and characterized using SEM, FTIR, EDAX, and XRD analyses. The results suggested that it is having a porous nature and cellulose crystal structure and confirmed the presence of chemical elements such as carbon (65.2%), oxygen (29.1%) as primary with Fe, Cl, Na and Ca as secondary elements. The performance of the biocomposite was evaluated for the dye adsorption using spectrophotometric methods. Various operating parameters were optimized using experimental methods and a maximum removal efficiency of 65% was achieved at a pH of 6, dosage of 5 g/L and an adsorption contact time of 120 min. The maximum efficiency (92.78%) was obtained with Fe-SS electrodes and KCl as a sustaining electrolyte under acidic circumstances (pH 6). The biocomposite was observed to be more efficient for higher dye concentration. Langmuir and Freundlich adsorption isotherms were fitted with the experimental results with R2 values as 0.926 and 0.980 respectively. The adsorption kinetics were described using Pseudo-first and Pseudo-second order models, wherein Pseudo-second order model fits the experimental results with R2 value of 0.999. The energy consumption of electrocoagulation (EC) process in the hybrid H-EC-BC system was compared to that of a standard EC process. The results demonstrated that the hybrid system is approximately 7 times more energy efficient than the conventional process, thereby implicating its adaptability for field application.

Preparation and Characterization of a Novel Lightweight Bio-Degradable Lignocellulosic Porous Molding Material

Wood is an abundant biomaterial and widely used in construction and furniture. Timber processing produces large amounts of residues and byproducts, which are of low value. In this study, we proposed a new strategy for the recycle of wood residues to prepare a wood porous molding material. A hydrated thermochemical grinding process followed by high-temperature and high-pressure refining was developed to convert wood powder into high-viscosity suspension. Lignocellulosic raw materials, including pine wood, beech wood, and bamboo, were compared with different grinding time. A porous material without the addition of synthetic adhesive was obtained with a density in the range of 0.28–0.67 g/cm3. The porous molding material was characterized based on fiber morphology, volume, and porosity and mechanical performance. Pores of different sizes were distributed in the samples randomly after curing and drying. The wood’s own bindings were released through the hydrated thermochemical grinding process. The porous sample made from bamboo with a grinding time of 6 h showed a high Young’s modulus (681.1 MPa), compactness (166.8 N/Sec), and hardness (517.6 N). Woody materials were more readily made into moldings since most of the cellulose crystal structure remained intact. The wood porous moldings are fully composed of lignocellulosic components and easy to recycle. This porous green material has great potential to be applied to insulation, ceiling, cabinet, and packaging.

Influence mechanism of K on cellulose pyrolysis by stepwise isothermal method in-situ DRIFTS method

The influence mechanism of alkali metal potassium (K) on cellulose pyrolysis is a vague and fundamental key topic in the field of biomass thermal conversion. In this study, the pyrolysis of cellulose and K-impregnated cellulose was compared by in-situ DRIFTS (Diffused Reflectance Infrared Fourier Transform Spectroscopy) and TG (Thermal Gravimetric)–MS (Mass Spectrum) experiment, and quantum chemical calculations were used to verify the peak position and pyrolysis mechanism of infrared (IR) spectroscopy. Stepwise isothermal in-situ DRIFTS was designed to study the reaction path at high temperatures. It was found that in the early stage of pyrolysis, K accelerated the activation of cellulose by attacking the hydrogen bond (H-bond) in the crystal structure of cellulose, increased the dehydration rate between molecules, and promoted the decomposition of cellulose. Simultaneously, it weakened the epoxy–ether bond, inhibited the formation of dehydrated sugar, and promoted the formation of furan. Subsequently, K combined with carbonyl groups to form C–O–K structures, which improved the thermal stability of certain oxygen-containing functional groups such as carbonyls/aldehydes, so that these structures were retained until higher temperature. K promoted the conversion of dehydrated sugars to straight-chain ketones/aldehydes, which led to an increase in carbon conversion. During the coke generation stage, K promoted the formation of disordered carbon and residues, thereby inhibiting coke aromatization. The isothermal in-situ DRIFTS method proposed in this study was demonstrated to better inhibit the high temperature drift of IR spectrum during pyrolysis. It clarified the conversion between functional groups at high temperatures, which is expected to promote the development of other high-temperature pyrolysis mechanism.

Extraction and Modification of Cellulose Microfibers Derived from Biomass of the Amazon Ochroma pyramidale Fruit

Microfibers are important to several areas of human lifestyle, and the knowledge about their physicochemical characteristics allows for proposing new technological applications. The in natura microfiber of Ochroma pyramidale fruit (IN sample) and its extracted pulp (PU sample) were evaluated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry and Differential Scanning Calorimetry (TG/dTG and DSC). Microfibers were composed mainly of (68 ± 1)% holocellulose, (35.8 ± 0.1)% cellulose, (32 ± 3)% lignin and (3.7 ± 0.3)% extractives. The XRD pattern of the PU sample revealed that the mercerization process resulted in the change of the cellulose crystal structure from Iα type (triclinic) to type II (monoclinic). The SEM technique showed that the IN sample presented regular cylindrical/hollow-shaped wire-like microfibers with diameters ranging from 5 µm to 25 µm. However, the mercerization process changed their natural morphology. A significant change in the FTIR spectra after the removal of hemicellulose and lignin components was observed: weak bands at 1739 cm−1 (C=O stretching of lignin and hemicellulose fractions), 1463 cm−1 (CH3 of lignin) and 1246 cm−1 (C-O of lignin) were still observed in the PU sample, indicating that the lignin was not completely removed due to the natural difficulty of isolating pure cellulose. The TG/dTG and DSC evaluation revealed a temperature increase of the second thermal event (starting at 235 °C) in the PU sample, which was assigned to the cellulose and residual hemicellulose degradation. Then, this work aimed to disseminate and characterize a microfiber with unusual characteristics still little explored by the scientific community, as well as its cellulosic pulp, providing information that may be useful in its application in different industries, enabling the positive development of new biocompatible, renewable and sustainable materials.

Comprehensive understanding of enzymatic saccharification of Betaine:Lactic acid-pretreated sugarcane bagasse

Green solvents, especially deep eutectic solvents (DESs), are widely applied to pretreat biomass for enhancing its enzymatic hydrolysis. In this work, lactic acid was selected as the hydrogen-bond-donor to prepare Betaine-base DES (Betaine:LA), The DES was utilized to pretreat sugarcane bagasse (SCB) at 160 ℃ for 80 min (severity factor LogR0 = 3.67). The influences of Betaine:LA treatment on the chemical composition, crystal and microstructure structure of cellulose, and cellulase digestion were investigated. The results showed that the lignin (47.1%) and xylan (44.6%) were removed, the cellulase digestibility of Betaine:LA-treated SCB was 4.2 times that of the raw material. This improved efficiency was attributed to the enhanced accessibility of cellulose, the weakened surface area of lignin, the declined hydrophobicity, and the decreased crystallinity of cellulose. Several compelling linear correlations were fitted between enzymatic hydrolysis and these alterations of physicochemical features, comprehensively understanding enzymatic saccharification of Betaine:LA-pretreated SCB.

Caustic and enzymatic effects on dissolving pulp and its performance as specialty fiber

Abstract The aim of this study was to investigate an effective approach for improving the dissolving pulp properties for making specialty fiber. The caustic and enzymatic treatment of the properties of dissolving pulp was conducted by analyzing the macromolecular structure and chemical composition. The results showed that the enzymatic treatment was more effective on influencing the macromolecular properties, while the caustic treatment had more influence on structural changing, mainly cellulose crystal structure and crystallinity. Meanwhile, to maintain a higher purity and higher brightness, caustic treatment would be beneficial in comparison with enzymatic treatment. The performance of caustic treated sample was evaluated in regarding to chemical composition and acetylation reaction performance, using commercial pulp as reference. The competitive feature of treated sample suggested its potential in future application.

Effect of Insoluble Dietary Fiber Extracted from Feijoa (Acca sellowiana (O. Berg) Burret.) Supplementation on Physicochemical and Functional Properties of Wheat Bread.

This study aimed to assess the effects of insoluble dietary fiber (IDF) from feijoa supplementation on the physicochemical and functional properties of wheat bread. The results showed that feijoa IDF (FJI) had the typical structures of hydrolysis fiber, polysaccharide functional groups, and crystal structure of cellulose. The gradual increase of FJI levels (from 2 to 8%) in wheat bread resulted in increased total DF, ash, and protein contents, accompanied by a reduction in moisture, carbohydrates, and energy value. The inclusion of FJI in the bread crumb caused a rise in both redness (a*) and yellowness (b*) values while decreasing the brightness (L*) relative to the control specimen. In addition, adding FJI up to 2% significantly increased total phenolic and flavonoid contents and antioxidant activity, as well as flavor score of supplemented bread samples, while additions above 2% resulted in undesirable taste and texture. FJI addition caused higher bile acid, NO2-, and cholesterol adsorption capacities. Moreover, FJI addition up to 4% significantly reduced glucose adsorption capacities at different in vitro starch digestion intervals. The findings revealed that FJI offers great potential as an ideal functional ingredient in food processing.

The crystalline structure transition and hydrogen bonds shift determining enhanced enzymatic digestibility of cellulose treated by ultrasonication

Global energy issue raised the necessity to develop second-generation biofuels, and biorefinery of cellulosic biomass becomes a promising solution. Various pretreatments were used to overcome the cellulose nature of recalcitrance and improve the enzymatic digestibility, but the lack of mechanism understanding hindered the development of efficient and cost-effective technologies of cellulose utilization. Using structure-based analysis, we demonstrate that the improved hydrolysis efficiency caused by ultrasonication was ascribed to the changed cellulose properties rather than the increased dissolubility. Further, isothermal titration calorimetry (ITC) analysis suggested that enzymatic digestion of cellulose is an entropically favored reaction driven by hydrophobic forces other than an enthalpically favored reaction. The changes in cellulose properties and thermodynamic paramenters due to ultrasonication accounted for the improved accessibility. Ultrasonication-treated cellulose showed porous, rough and disordered morphology, accompanying with the loss of crystalline structure. Despite the unaffected unit cell structure, ultrasonication expanded the crystalline lattice by increasing grain sizes and average cross-sectional area, resulting in the transformation from cellulose I to cellulose II, with the decreased crystallinity, better hydrophilicity and increased enzymatic bioaccessibility. Furthermore, FTIR combined with two-dimensional correlation spectroscopy (2D-CoS) verified that the sequential shift of hydroxyl group and intramolecular/intermolecular hydrogen bonds, the functional groups governing cellulose crystal structure and stability, accounted for the ultrasonication-induced transition of cellulose crystalline structure. This study provides a comprehensive picture of cellulose structure and property response caused by mechanistic treatments and will open up avenues to develop novel pretreatments for efficient utilization.

Filtration Capacity and Radiation Cooling of Cellulose Aerogel Derived from Natural Regenerated Cellulose Fibers

ABSTRACT Natural cellulosic materials are attractive biopolymers for their naturally abundant source, mechanical toughness, bioactivity, etc. However, porosity and flexibility remain challenges for the preparation of aerogels from natural cellulose. To maintain the characteristics of cellulose aerogels possessing the toughness of fibers and high porosity of aerogels, cellulose aerogels with three-dimensional void structures and high compressive resilience were prepared by mixing cellulose fiber suspension and polyvinyl alcohol (PVA). The PM 2.5 removal rate and thermal conductivity of cellulose aerogel reached 92.4% and 0.028 W/mK, respectively, when a PVA content of 0.7% was added, and the radiation cooling temperature was about 10.0°C lower than that of PE foam. The three-dimensional void structure and surface morphology of the cellulose aerogels were investigated by scanning electron microscopy (SEM). The cellulose aerogel porosity and pore size distribution were evaluated by a mercury intrusion meter. The crystal structure of cellulose was analyzed by X-ray diffraction (XRD). UV-Vis-NIR spectroscopy was used to investigate the infrared reflectance of cellulose aerogels. Then the air purification efficiency and radiation cooling effect of porous cellulose aerogels were evaluated in a homemade device, respectively.

Rapid and massive fractionation of hemicelluloses for purifying cellulose at room temperature by tetramethylammonium hydroxide

The fractionation of hemicelluloses is a promising method to improve the comprehensive utilization of lignocellulosic biomass. However, the effective fractionation of hemicelluloses is always limited by the structural complexity and easy degradability. In this study, tetramethylammonium hydroxide (TMAH) was developed to fractionate hemicelluloses from poplar holocellulose with high molecular weights and high yields at room temperature. Approximately 90% of hemicelluloses could be dissolved at room temperature in 1 h, and the yield was up to 81.9%. Compared with the fractionation using NaOH solution, the hemicelluloses isolated by TMAH solvent showed a more complete structure and higher purity. Meanwhile, the retention rate of cellulose after treatment with TMAH was up to 90.2%, and the crystal structure of cellulose in the residues was practically unchanged. Moreover, the TMAH solvent could be recycled to fractionate hemicelluloses. The work provides an elegant and significantly efficient method towards hemicelluloses fractionation and cellulose purification.

Molecular and crystal structures of cellulose in severely deteriorated archaeological wood

Preservation and conservation of archaeological wooden artifacts is extremely challenging due to a lack of knowledge about the hierarchical structure of preserved cellulose. Herein we report on the comparative analysis of eight archaeological and four recent wood samples from three archaeological sites in China by a variety of methods, including micro-morphology, Fourier Transform Infrared Spectrum, X-ray scattering, chromatographic analysis of wood sugars, and solid state 13C CP/MAS NMR. Results show that deterioration on the microscale is clearly related to a fragmentation of both the cellulose crystallite structure and the cellulose microfibrils. Slightly deteriorated archaeological wood features cellulose crystallites and microfibrils, comparable to non-degraded recent wood, whereas severely deteriorated wood shows higher porosity of the wood cell wall, fragmented cellulose aggregates instead of fibrils and nearly no crystallinity. Alterations in molecular structures resulted in advanced degradation of both amorphous and crystalline cellulose domains. Only a small amount of cellulose was preserved. The data allows to assume highly fragmented but still partially crystalline cellulose lamellas.Graphical abstract

Adsorptive removal of Cu(II) from aqueous solution by fermented sweet sorghum residues as a novel biosorbent

Sweet sorghum straw is a kind of natural wood cellulose with high porosity and high specific surface, which is theoretically conducive to the physical adsorption of heavy metal ions. In this paper, we reported a new biosorbent, the fermented sweet sorghum residues (FSSR), which is a byproduct of bioethanol production by fermentation of sweet sorghum straw, for the removal of Cu(II) from aqueous solution. The properties of the adsorption of Cu(II) on SSR and FSSR were studied and compared. The adsorption process of Cu(II) by SSR and FSSR conformed to the Elovich kinetic model. The isothermal adsorption process conformed to the Freundlich and the Tempkin models. The adsorption capacity of FSSR for Cu(II) was increased with the increase of pH. The adsorption mechanism of Cu(II) by FSSR was mainly attributed to ion exchange. SSR and FSSR were characterized by SEM-EDS, FTIR and XRD. The surface of FSSR had microporous structure, the content of –OH and other active functional groups increased. The fermentation has a certain destructive effect on the crystal structure of cellulose with the increase of amorphous structure. Therefore, fermentation process could be regarded as an effective means of microbial modification, to destroy the structure of the straw and result in the porous structure, which improved the adsorption capacity of SSR for heavy metals. FSSR could be used as a potential biosorbent for heavy metal removal from aqueous solution. Ethanol fermentation might be an effective method to improve performance of biosorbent for Cu adsorption.

Extraction optimization, structural characterization of soluble dietary fiber from Morchella importuna, and its in vitro fermentation impact on gut microbiota and short-chain fatty acids

ABSTRACT Soluble dietary fiber was extracted from spent Morchella importuna by optimizing the extraction conditions using the response surface method. Response surface analysis results indicated that the extraction yield of MI-SDF reached up to 15.38 ± 0.16% under the optimized conditions with optimal lye concentration of 2.9%, extraction temperature of 71°C and extraction time of 2 h. The results of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analyses suggested that M. importuna-derived soluble dietary fiber (MI-SDF) exhibited the typical porous fiber structures, polysaccharide functional groups, and cellulose crystal structure. And MI-SDF was applicable to food processing at <250°C. During in vitro fecal fermentation, MI-SDF significantly increased the abundance and diversity of beneficial bacteria and decreased those of harmful bacteria. The levels of total and individual short-chain fatty acids were significantly increased. This study will provide valuable information for further investigation of MI-SDF.

Direct carboxylation of cellulose in deep eutectic solvent and its adsorption behavior of methylene blue

The surface of cellulose particles was carboxylated (2.44 mmol/g) in a deep eutectic solvent containing carboxylic acid. Based on the carboxyl content, the effects of key factors on cellulose carboxylation was systematically investigated. In addition, the reaction mechanism was studied by using liquid chromatography-mass spectrometry, and the influence of deep eutectic solvent containing carboxylic acid on the structure and physicochemical properties of cellulose during carboxylation was examined using different characterization techniques. The results showed that the type of carboxylic acid, cellulose particle size, and pretreatment methods significantly affect the carboxylation efficiency, degradation, and carbonization of cellulose. The internal crystal structure of cellulose did not change after the carboxylation reaction, while the surface crystal structure was destroyed by carboxylation, which greatly improved the dispersion and hydrophilicity properties of the product. The kinetics and thermodynamics of carboxyl cellulose adsorption were studied as well. Potential application of carboxyl cellulose in the adsorption of pollutants was demonstrated. This study provides a new method for the direct modification of cellulose in deep eutectic solvents, as well as a new sustainable strategy for modifying other materials.

The impact mechanism of chlortetracycline on different stages of anaerobic fermentation of organic wastes

Chlortetracycline (CTC) is widely used in animal husbandry, which is directly discharged into the environment through feces due to incomplete absorption by animals, resulting in the continuous accumulation of chlortetracycline in the soil and water environment. In order to explore the effect of CTC addition on the microbial population and richness during the three stages of the anaerobic fermentation (AF), firstly, the samples of control group (CK), hydrolysis + CTC (HC)，acidification + CTC (AC) and methanogenesis + CTC (MC) group were set, respectively. Then, the 100 mL of 4.0 g/L CTC solution was added into the AF reactor of the HC, AC and MC on the 8th, 16th and 24th day and sampled with high-throughput sequencing analysis of microbial flora. The results showed that no matter the CTC added in any fermentation stages, it would have impacts on the microbial activity, cumulative gas production, cellulose crystal structure and functional group absorption peak intensity during the AF. In particular, it had a significant inhibitory effect on the biological activities of the SBR1031, Hydrogenispora and Ruminiclostridium_1 in the acidification stage and the Anaerolinea in the methanogenesis stage, which showed that CTC mainly inhibited the growth and reproduction of microorganisms in the acidification stage to inhibit the subsequent advancement of the entire fermentation. Consequently, the CTC addition had a significant inhibitory effect on microorganisms in different stages, which illustrated the pretreatment of organic waste contained CTC was necessity before the AF treatment.

Dissolution of HwBKP with [Bmim]Cl-DMF Solvent and Production of Cellulose Beads: Effect of Mixing Ratio of Solvents

Hardwood bleached kraft pulp (HwBKP) was dissolved with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and N,N-dimethylformamide (DMF) at 110℃, and cellulose beads were prepared by dropping the [Bmim]Cl/DMF/cellulose solution into water. The effects of the mixing ratio of [Bmim]Cl and DMF on the properties of the cellulose solution and beads are investigated in this paper. Increasing the DMF ratio decreased the viscosity and surface tension of the cellulose solution. Moreover, all cellulose solutions with various mixing ratios of [Bmim]Cl and DMF showed shear thinning behavior. The cellulose beads with 800-1500 μm diameters were prepared by varying the mixing ratio of [Bmim]Cl and DMF (the cellulose concentration was 3%; the inner diameter of a syringe needle was 0.41 mm). Increasing the DMF ratio increased the particle size of the cellulose beads, and increasing this ratio over 40% created a rough surface on the beads. During dissolution with [Bmim]Cl and DMF and regeneration in water, the cellulose crystal structure was changed to cellulose II and the crystallinity of the cellulose decreased. In addition, the thermal stability of the cellulose beads was slightly lower than that of the HwBKP.

A simple method for functionalization of polypyrrole-coated cotton fabrics by reduced graphene oxide for UV screening

Here, the modified Hummer’s method was used to prepare reduced graphene oxide (RGO) nanostructures. The functional properties of the prepared RGO nanostructures were studied by using the X-ray diffraction method (XRD), and scanning electron microscopy (SEM). Using the in situ polymerization process, polypyrrole (PPy) was prepared. During polymerization, an ultrasound-assisted coating process was used to coat the cotton fabrics. In addition, the Nafion@RGO composite mixture was deposited on the surface of PPy- coated cotton fabric by dip and dry method. The presence of cellulose crystal structure was confirmed by conducting a structural study of the coated and uncoated (UC) cotton fabrics. The presence of a characteristic functional group was confirmed by the Fourier transform infrared spectroscopy–Attenuated total reflection (FTIR–ATR) study of the fabrics. Wrinkled-like morphology with a proper binding of PPy with RGO was revealed by SEM analysis. Our results showed that the RGO coated fabrics could be distributed on the cotton fabric and possessed better thermal stability and wettability properties than uncoated cotton fabric. Ultraviolet (UV)-screening properties of the coated and uncoated fabrics confirmed the better performance of the coated cotton fabrics in the order of Nafion/RGO coated fabrics (RGPC) > PPy/Cotton (PC) > UC. The transmission and screening efficiency of RGO coated fabrics were 0.02% and 99.98%, respectively. Thus the Nafion/RGO/PPy fabrics is a safe and promising UV screening and have great potential application in the all wearable textile sector.

Physicochemical transformation and enzymatic hydrolysis promotion of reed straw after pretreatment with a new deep eutectic solvent

This work proposed a promising biorefinery method for the deconstruction of reed straw by using a novel deep eutectic solvent (DES) consisted of benzyltriethylammonium chloride/formic acid (BTEAC/FA). BTEAC/FA showed significant delignification and xylan removal while preserving most of the cellulose. Under the optimum conditions (molar ratio: 1:6), the glucose yield of cellulose-rich substrates by enzymatic hydrolysis reached 76.64%, which was about 5.24-fold higher than that of raw reed straw. The removal of lignin and hemicellulose and the changes in the cellulose crystal structure were presumed to the reason for enhancing enzymatic hydrolysis efficiency. The highest lignin yield reached 78.34%. Moreover, the lignin exhibited high purity (84.25%–91.45%), medium molecular weight (3812–9918 g/mol), and low polydispersity (1.47–2.75) because of the cleavage of β-O-4 and β-β linkages. Overall, this work provided a theoretical basis for the in-depth utilization of reed straw.

Distinguishing liquid ammonia from sodium hydroxide mercerization in cotton textiles

The question addressed in this paper is whether cotton textiles mercerized with liquid ammonia (L-NH3) can be distinguished from NaOH mercerized cotton textiles with FTIR-ATR spectroscopy. In collaboration with a process-house, cotton textiles were treated with L-NH3, NaOH, neither or both. The treatment conditions were set to mimic commercial-scale operations. The samples were then analyzed with FTIR-ATR spectroscopy, and for comparison, also with powder X-ray diffraction. The analyses were aimed at detecting changes in the cellulose crystal lattice structure that result from the two mercerization processes. The measured spectra and diffractograms were evaluated both visually and with Principal Component Analysis (PCA), and the results show that with FTIR-ATR spectroscopy it was possible to differentiate between the untreated, L-NH3 mercerized and NaOH mercerized textiles, whereas with X-ray diffraction it was difficult to detect differences between the untreated and treated samples. The better performance of FTIR-ATR spectroscopy is attributed to the method being more sensitive to changes on sample surfaces, whereas X-ray diffraction results are more representative of the sample bulk. The samples were treated under conditions mimicking commercial-scale operations, which are optimized to maximize treatment speed. Hence, the mercerization induced changes are likely to be limited to sample surfaces and hence detectable with FTIR-ATR spectroscopy but not with X-ray diffraction. It is reported that Sum Frequency Generation Vibrational Spectroscopy, another surface-limited analytical method, may also be employed for detection of mercerization type, but FTIR-ATR spectroscopy has the advantages of ease of operation and the devices are less expensive.

Structure, physicochemical, and in vitro functional properties of insoluble dietary fiber from bamboo culm: A potential functional ingredient

Bamboo culm contains abundant hemicellulose, cellulose, and lignin, which was a high-quality insoluble dietary fiber (IDF) raw material. In this paper, the effects of alkaline hydrogen peroxide (AHP) and enzymatic hydrolysis on physicochemical and functional of bamboo IDF (named BIDF and OIDF, respectively) were reported. SEM, FT-IR, and XRD analysis suggested that both BIDF and OIDF had the functional groups of insoluble cellulose and crystal structure of cellulose. AHP treatment effectively improved the water-holding capacity (WHC), water swelling capacity (SC), and glucose absorption capacity (GAC). Enzymatic hydrolysis effectively improved the glucose dialysis retardation index (GDRI), bile acid salt absorption capacity (BAC), cholesterol-adsorption capacity (CAC), and nitrite ion absorption capacity (NIAC). In addition, they all exhibited great toxic ions adsorption (Cd2+, Pb2+). The above results showed that bamboo culm IDF could be used as an ideal functional ingredient in food processing. Practical applications Insoluble dietary fiber (IDF) provides various beneficial functions, such as hypoglycemic and hypolipidemic. We used alkaline hydrogen peroxide treatment (AHP) and complex enzymatic hydrolysis to improve the physicochemical and functional properties of bamboo IDF and help to the further research on its application value in food and other industry. The bamboo culm IDF could be incorporated into other food products for enhancing textural properties and promoting a favorable mouthfeel and it was an ideal functional ingredient in food processing.