Research Articles

Polysaccharides were isolated from Phyllostachys acuta leaves by microwave-assisted extraction under various temperatures and time. The obtained polysaccharides were characterized by acid hydrolysis, the Folin-Ciocalteu method, and Fourier transform infrared spectroscopy (FTIR). The major monosaccharides presented in the extracts were arabinose (258.0 mg/g to 414.5 mg/g), galactose (167.0 mg/g to 289.2 mg/g), and glucose (157.4 mg/g to 246.7 mg/g) along with some mannose, fructose, and xylose. The total phenol yield of the bamboo leaves was 0.31 mg/g to 0.73 mg/g. The FTIR spectra revealed that the polysaccharides mostly consisted of β-glycosidic linkages. For the cytotoxicity, the presence of polysaccharides considerably elevated the multiplication of HepG2 cells and showed no growth inhibition for the samples. For the antioxidant activities, the polysaccharides exhibited excellent abilities both in the diphenyl picrylhydrazyl radical potential (DPPH) assay and ferric reducing antioxidant potential (FRAP) assay. The results suggest that bamboo leaf polysaccharides have great potential to be applied in the food, healthcare, and pharmaceutical fields.

A two-stage, pH- and temperature-controlled wheat bran fermentation method using Aureobasidium pullulans was investigated for feruloyl oligosaccharides (FOs) production and the activities of xylanase, xylosidase, and ferulic acid esterase (FAE). A. pullulans secreted xylanase, xylosidase, and FAE at high levels in the initial pH of 4.0 to 5.0 and a fermentation liquid temperature of 31 °C to 33 °C. FOs production via two-stage fermentation (FOs 2) reached 1123 nmol/L after fermentation for 96 h, by controlling the initial pH at 4.0 and the initial temperature at 33 °C, and then changing the pH to 6.0 and the temperature to 29 °C at the same time at 36 h. This process was 12 h shorter and 219 nmol/L higher than a one-stage fermentation for producing FOs 1. Xylanase, xylosidase, and FAE activities were highly correlated with controlled pH and temperature and FOs biosynthesis rate. Thus, the combination of two-stage controlled pH and temperature could support mass production of FOs.

The non-catalytic hydrothermal pretreatment of softwood is generally less effective for subsequent enzymatic hydrolysis. In this study, the efficacy of hot-compressed water (HCW) treatment of Douglas fir was investigated between 180 °C and 260 °C, allowing solubilization of the cellulose components. The enzymatic digestibility of cellulosic residues increased significantly under HCW conditions > 250 °C, and the enhanced glucan digestibility was closely related to the decomposition of the cellulose component. Combination of the first-stage HCW treatment (220 °C, 5 min) to recover hemicellulosic sugars with the second-stage HCW treatment (260 °C, 5 min) to improve cellulose digestibility gave a total sugar recovery of 56.2% based on the dried raw materials. This yield was 1.4 times higher than that from the one-step HCW-treated sample (260 °C, 5 min). Additionally, an enzymatic hydrolysate from the two-step HCW-treated sample exceeded 90% of the ethanol fermentation yield based on the total sugars present in the hydrolysates. These results suggest the potential of the two-step HCW treatment of softwood as a pretreatment technology for efficient total sugar recovery and ethanol production.

The saccharification of laccase-pretreated empty fruit bunch (EFB) was optimized in a lab-scale experiment using one-factor-at-a-time (OFAT) and response surface methodology (RSM). After pretreatment, the degree of delignification was checked by noting the weight loss (%) after pretreatment, and also by the quantity of total sugar produced after saccharification with cellulase enzyme. OFAT studies of saccharification of the pretreated EFB showed that the biomass was best saccharified using cellulase enzyme at the following conditions: enzyme concentration of 30 IU/g of EFB, substrate concentration of 5.0% w/v, 50 °C, saccharification time of 24 h, and pH 5. This combination exhibited the highest yield of total sugar (28% w/w). Although 29% w/w yield was achieved with an enzyme concentration of 40 IU/g of EFB, this increase in yield was not proportional to the increased enzyme concentration and, therefore, was considered insignificant. Statistical analysis of the combined effects of pH and temperature showed that pH had a more significant effect than the temperature on the saccharification process, based on a P < 0.05 significance level. The effect of pH on total sugar production was more significant than the temperature in both linear and quadratic functions. In sum, the saccharification of laccase-pretreated EFB should follow the optimized process conditions achieved in the current study.

The objective of this study was to determine a correlation between the dynamic modulus of elasticity (MOEd) and the static modulus of elasticity (MOEs), and to assess the potential of using nondestructive (NDT) methods as a grading tool for both treated and untreated wood exposed to weathering. In the experiment, test samples made from spruce and oak were exposed for four months to natural weathering. Half of the specimens were treated with a silicon-based nano-protection. The MOEd was determined using acoustic NDT methods–ultrasound transmission (MOEdu) and the vibration methods (MOEdv), while the MOEs was determined by a destructive three-point bending test. The results showed that there was no statistical significance for the influence of the time of exposure and the surface treatment on the modulus of elasticity. The ultrasound method, measured in the longest distance of the sample, had the most significant correlation with the MOEs. The vibration method also reached a similar correlation with the MOEs. The mean values of the MOEdu and MOEdv were higher than the MOEs. The influence of density on the acoustic wave velocity was not confirmed.

This research introduces one of the most important historic constructions in Gorgan, namely, the House of Bagheri, placing an emphasis on wooden materials, noting that a considerable amount of solid wood was utilized as a structural element of this building. First, anatomical identification of species of wood was performed by the microscopic identification. The mechanical properties of selected old structural members were determined and compared with standard values, as well as visually inspected by an expert carpenter. The results indicated that several domestic hardwoods and one imported softwood had been used, and that old members (~ %36) showed acceptable mechanical strength despite their decayed appearance. The results implied that the visual inspections were very conservative and not reliable for restoration operations.

The surface roughness in plane milled Scots pine wood that was thermally modified at 190 °C and 220 °C was examined. Indicators of wood surface roughness included the three most commonly applied parameters, arithmetic mean surface roughness (Ra), surface roughness depth (Rz), and total height of the roughness profile (Rt). Roughness was tested separately for earlywood and latewood using two feed speeds of 1 and 5 m/min. The thickness of the milled layer was 1 mm. The effect of all controlled factors, i.e., feed speed, temperature of modification, and place of measurements, on the parameters of surface roughness were statistically significant (P < 0.05). Surface roughness increased with an increase in feed speed, whereas it decreased with an increased modification temperature. Latewood was characteristically lower in roughness than earlywood. The greatest differences in homogenous groups for the determination of the roughness parameters were found in measurements taken on earlywood and latewood, while the smallest differences were recorded for different feed speeds.

This work has established the optimum reaction conditions in a biphasic system using microcrystalline cellulose as the raw material, an ionic liquid as the solvent, metal chloride as a catalyst, and an organic solvent as the extraction reagent. The optimum reaction conditions were microcrystalline cellulose:ionic liquid – 1:10 (mass ratio), chromium(III) chloride (CrCl3) – 6.8 mol% (based on the glucose unit of cellulose molecule), reaction time – 3 h, temperature – 130 °C, and mass ratio of 1-butyl-3-methyl-imidazolium chloride ([BMIM]Cl) to methylbenzene – 1:4.4]. Under these conditions, the yields of glucose and 5-(hydroxymethyl)furfural (5-HMF) were 27% and 55%, respectively. The solvent [BMIM]Cl could be reused twice. The first recovery rate of [BMIM]Cl was approximately 70.9%. The product 5-HMF was obtained in 64.7% yield, which decreased after the first [BMIM]Cl recycling. The second recovery rate of [BMIM]Cl was 45%. The yield of 5-HMF was 39.6%, which decreased after the second recycling of [BMIM]Cl. In this paper, the energy consumption, operation, reutilization of [BMIM]Cl, and product yields of a one-phase system and a biphasic system were compared. Experimental results demonstrated that the biphasic solvent system was suitable for the degradation of cellulose to glucose and 5-HMF.

A bacterial endo-polygalacturonase (endo-PGase) gene from the plant pathogen Pectobacterium carotovorum was cloned into pGAPZαA vector and constitutively expressed in Pichia pastoris. The recombinant endo-PGase secreted by the Pichia clone showed a 1.7 fold increase when the culture medium included glycerol in replacement of glucose as the carbon source. The enzyme had optimum activity at pH 5.5 and 40 °C with stability between pH 5.0 and 8.0 and at temperatures up to 50 °C. The enzyme activity was enhanced by 41% with the addition of 1 mM Co++, and inhibited by Fe++ with a 63% reduction. The mode of the enzyme action showed internal cleavage of α-1,4 glycoside bonds of polygalacturonic acid and citrus peel pectin. Trigalacturonate and hexagalacturonate were the main hydrolysis products, with a yield of 0.44±0.01 and 0.21±0.01 mg released per mg polygalacturonic acid substrate, respectively. This represents the first report of a microbial endo-PGase that produced trimer and hexamer uniquely as the end products of hydrolysis, in contrast to mixtures of mono-, di-, and trigalacturonates commonly observed for the action of fungal enzymes. Pectic oligosaccharides generated from native carbohydrate polymers offer the potential application as building blocks for value-added products.

A novel fire-resistant adhesive made from polyvinyl alcohol, urea, phosphoric acid, and starch was demonstrated for use as a binder and fire retardant to produce ultra-low density fibreboard (ULDF) with clear environmental benefits. The results from Fourier transform infrared spectroscopy showed the presence of chemical bonding between fire-resistant adhesives and ULDFs. The limiting oxygen index (LOI), combustion behaviour, and thermal stability were characterized using a LOI text, cone calorimeter, and thermal analyzer, respectively. The results demonstrated that the LOI value of the fire-retardant ULDF can reach up to 34.2 with 300 mL of fire-resistant adhesive. It was established that the additive noticeably reduced the peak of heat release rate, total heat release, and total smoke release of ULDF. Their morphologies after combustion were elucidated using a scanning electron microscope, and a char layer in the condensed phase was observed. Thermal analysis showed that the thermal stability of ULDF improved dramatically and the residual weight increased 4-fold, to 48.32%. Therefore, such ULDFs will be tremendously attractive as renewable, sustainable, and bio-based insulating materials.