High-pressure Steam Treatment Research Articles

Effects of pretreatment on the microcharacterization and fermentation of bamboo shoot shells

This study focuses on the pretreatment and characterization of natural fibers from the bamboo shoot shell (BSS) of Phyllostachys heterocycla to determine their suitability as biorefining materials. The discarded bamboo shoot shell was used as a source of fibers, which were analyzed for their physical, chemical, and microstructure properties. Fourier transform infrared spectroscopy, X-ray diffraction spectra, and scanning electron microscopy confirmed that a mixture of sodium hydroxide immersion plus high-pressure steam treatment allowed the cellulose structure to be disrupted, providing more adsorption sites for cellulases. Gas chromatography mass spectrometry (GC-MS) also showed that the pretreatment exposed the internal structure of the fibers and that high-mass silicon compounds were present in the eluted solution. After adding the cellulase produced by Trichoderma viride and Aspergillus niger, the reducing sugar yield was increased by 268% and 251%, compared to unpretreated BSS fibers. This strategy may apply to many industries, especially biorefining and lignocellulose biotransformation technology.

Fabrication of High-Performance Densified Wood via High-Pressure Steam Treatment and Hot-Pressing.

The fabrication of sustainable structural materials with high physical properties to replace engineering plastics is a major challenge for modern industry, and wood, as the most abundant sustainable natural raw material on the planet, has received a great deal of attention from researchers. Researchers have made efforts to enhance the physical properties of wood in order to replace plastics. However, it is also difficult to meet practical demands at a low cost. Herein, we report a simple and efficient top-down strategy to transform bulk natural basswood into a high-performance structural material. This three-step strategy involves partial removal of hemicellulose and lignin via treating basswood by boiling an aqueous mixture of NaOH and Na2SO3, and a high-pressure steam treatment (HPST) was applied to delignified wood followed by hot-pressing, which allowed the wood to absorb moisture uniformly and quickly. HPST-treated dense delignified wood (HDDW) has a tensile strength of ~420 MPa, which is 6.5 times better than natural basswood (~65 MPa). We systematically investigated the various factors affecting the tensile strength of this wood material and explored the reasons why these factors affect the tensile strength, as well as the intrinsic connection between the moisture absorbed through HPST and the increased tensile strength of HDDW. Through our experiments, we realized the enhancement mechanism of HDDW and the optimal experimental conditions for the fabrication of HDDW.

Variation in structural and in vitro starch digestion of pulse cotyledon cells imposed by temperature-pressure-moisture combinations.

Starch digestibility in whole pulses is affected by food structural characteristics, which in turn can be modulated by processing methods. In present study, high-pressure steam (HPS) and hydrothermal treatment (HT) with different moisture content were applied to clarify the mechanisms of processing variables affecting in vitro starch digestibility in pulse cells. Based on thermal and X-ray results, the relative crystallinity of cells decreased after HPS and HT treatments. However, HPS-treated cells under higher (>50%) moisture content showed insignificant discrepancies in crystallinity than HT samples. Starch digestion in HPS-treated cells increased with higher moisture content but was still lower than in HT samples. Results of FITC-dextran diffusion and methyl esterification of cell walls indicated that cells with higher wall permeability exhibited relatively higher starch digestibility. This study suggests that the enzyme susceptibility to starch in cells is dominantly influenced by cell wall structure, which could be optimized through processing variables.

High-pressure steam treatment with Pt/TiO2 enhances the low temperature formaldehyde oxidation performance

A facile high-pressure steam treatment is developed to improve the formaldehyde oxidation performance of the typical Pt/TiO2 catalyst at low temperatures. The formaldehyde oxidation rate of the treated Pt/TiO2 catalyst can be increased by 4.8 times compared with that of the pristine one. Simultaneously, the treated Pt/TiO2 catalyst possesses the good catalytic stability and catalytic resistance to dry environment. The kinetic study shows that formaldehyde molecules are more liable to be oxidized on the treated Pt/TiO2. A series of characterization results display that the structural parameters of Pt and TiO2 treated with high-pressure steam are not altered. It is found that a layer of bound water is formed on the surface of Pt nanoparticles, which can modify some surface properties of treated Pt/TiO2 catalyst. The interaction strength of intermediates (e.g. CO) with Pt is significantly weakened. Moreover, the amounts of oxygen species and surface hydroxyl for HCHO oxidation are dramatically increased on the treated Pt/TiO2. Based on these characteristics, two reaction steps of formate and CO can be accelerated to enhance the low temperature HCHO oxidation performance of treated Pt/TiO2 catalyst according to the HCHO-DRIFTS studies.

Garbage to Nanocellulose: Quantitative Isolation and Characterization of Steam-Treated Carboxymethyl Holocellulose Nanofibrils from Municipal Solid Waste

Municipal solid waste (MSW) is a major source of greenhouse gas emissions unless its carbons are sequestered into higher-value products. This study focuses on isolating organic solids and cellulose-rich fibers from MSW via high-pressure steam treatment and converting the fibrous, prepulped materials from wastepaper, packaging materials, cardboard, etc., into value-added cellulose nanofibrils. Chemical–mechanical defibrillation of steam-treated municipal solid waste was optimized using heterogeneous and nonregioselective carboxymethyl etherification coupled with shearing by blender, thus transforming a heterogeneous mix of MSW into homogeneous carboxymethyl holocellulose nanofibrils without the use of conventional pretreatments of crude cellulosic feedstock. These carboxymethylated, hemicellulose-coated, cellulose nanofibrils were isolated quantitatively at >95% yield with widths 3–8 nm, thicknesses 1–3 nm, and lengths up to 1000 nm. We posit that this advancement of combining an inexhaustible, global supply of waste cellulose, large-scale steam autoclaving pretreatment, and an industrially relevant carboxymethylation process could unlock the higher potential of sustainable cellulosic nanomaterials for a circular economy.

Inhibition of the fishy odor from boiled crab meatballs during storage via novel combination of radio frequency and carbon dots

Use of combination of radio frequency (RF) and carbon dots (CDs) was performed to pasteurize and reduce the fishy odor from boiled crab meatballs during storage. Due to the best pasteurization effect and relatively short treatment time, CDs combined RF heating for 30 min (CDRF30) was selected as the optimal CDRF treatment. The efficacy of CDRF30 was evaluated and compared to those of CDs treatment and high pressure steam (HPS) treatment. After stored for 15 days at 4 °C, the trimethylamine (TMA) concentration in CDRF30 group (80.95 μg/kg) was remarkably lower than those in control and CDs group; the total concentration of pentanal, hexanal, heptanal, and decanal (200.99 μg/kg), which were contributed to fishy odor in CDRF30 group were remarkably lower than those in control group, CDs group and HPS group. The results indicated that CDRF treated for 30 min can be a new pasteurization method for inhibiting the formation of fishy odor from boiled crab meatballs during refrigerated storage. • CDs combined RF heating for 30 min (CDRF30) was the optimal CDRF treatment. • CDRF30 can reduce the colony forming units in boiled crab meatballs. • CDRF30 can reduce lipid oxidation in boiled crab meatballs during storage. • CDRF30 can inhibit the production of fishy odor from boiled crab meatballs during storage.

Antioxidant activity of water extract from bamboo by high-temperature and high-pressure steam treatment

The antioxidant activity of water extract from bamboo by high-temperature and high-pressure steam treatment was analyzed. Bamboo was decomposed by high-temperature and high-pressure steam treatment, and more decomposition products were extracted with water extraction. The maximum antioxidant activity, i.e., EC50 = 0.127 mg/mL, and the maximum flavonoid content, i.e., 3.94 mg-quercetin equiv./g-dry weight bamboo, of water extract were obtained at a treatment pressure of 30 atm for a steaming time of 5 min. Compared with the untreated sample, they showed about 4.16 times higher of antioxidant activity and 6.02 times higher of flavonoid content. The maximum total polyphenol content, i.e., 35.7 mg-catechin equiv./g-dry weight bamboo, of water extract was obtained at 25 atm for 5 min. Compared with the untreated sample, it showed 6.69 times higher of total polyphenol content. The water extract from bamboo by high-temperature and high-pressure steam treatment was fractionated by high-performance liquid chromatography (HPLC). The structure of the fraction showing the highest antioxidant activity in the fractionated extract was determined. It had a structure having two highly reactive phenolic hydroxyl groups. The two phenolic hydroxyl groups reacted with reactive oxygen species (ROS) to cause a reduction reaction, thereby exhibiting antioxidant activity.

Production of Eco-refinery Pulp from Moso Bamboo Using Steam Treatment Followed by Milling Treatment

In this study, we produced cellulose nanofiber (CNF) from moso bamboo using high-temperature and high-pressure steam treatment combined with the milling treatment. This pretreatment method can be considered as an environmentally friendly method because the treated product contains only wood-derived components and water that generally do not lead to significant corrosion problems and formation of neutralization sludge. The specific tensile strengths of CNF obtained in this work were almost the same values as that of a commercial CNF. Furthermore, an eco-refinery pulp was made of holocellulose and CNF those were obtained from moso bamboo by this pretreatment method and its mechanical strength was evaluated. By changing the steam treatment conditions, it is possible to produce eco-refinery pulp of various specific tensile strengths adapted to the application and purpose.

Effect of high-pressure saturated steam treatment on the flavor, browning and solubility of micro soy flour

Effect of high-pressure saturated steam treatment on the flavor, browning and solubility of micro soy flour

Production of cellulose nanofibers from Aspen and Bode chopsticks using a high temperature and high pressure steam treatment combined with milling

Holocellulose was generated from Aspen and Bode chopsticks by high temperature, high pressure steam treatment combined with milling. The steam treatment conditions were increased, the holocellulose component ratio in the treated sample as well as its molecular weight decreased. The treated holocellulose was subjected to grinder treatment to obtain cellulose nanofibers (CNF). Field-emission scanning electron micrographs indicated that CNF were successfully produced. The maximum tensile strength values of 86.9 and 109.9 MPa/(g/cm3) for Aspen and Bode, respectively, were obtained at a steam pressure of 15 atm and steaming time of 5 min. Furthermore, it was demonstrated that the optimal molecular weight of holocellulose to produce CNF with high tensile strength was around 1.2 × 105, while the optimal holocellulose recovery rate (HR; the degree of fibrillation was defined as HR in this study) was around 1.00.

Microstructure and corrosion performance of steam-based conversion coatings produced in the presence of TiO 2 particles on aluminium alloys

Abstract The steam-based conversion coatings containing TiO 2 particles were prepared using a two-step process comprising of spin coating of particles onto an aluminium substrate followed by a high-pressure steam treatment. Process has resulted in the formation of aluminium oxide layer (~ 1.3 μm thick) embedded with TiO 2 particles. The electrochemical measurements show the beneficial effect of TiO 2 particles in the oxide layer by exhibiting lowest anodic and cathodic activities, and reduced pit depth. The presence of TiO 2 particles shifts the corrosion potential values to positive side (noble side) when compared to the coatings without TiO 2 particles, while the shift in the pitting potential was a function of the steam treatment time and degree of particle incorporation into the oxide.

PHYSICOCHEMICAL PROPERTY CHANGES OF OIL PALM MESOCARP FIBERS TREATED WITH HIGH-PRESSURE STEAM

High-pressure steam treatment (HPST) is a potential alternative method for the modification of lignocellulosic materials. The effect of HPST on oil palm mesocarp fibers (OPMF) was successfully investigated with treatment conditions of 170 oC/ 0.82 MPa, 190 oC/ 1.32 MPa, 210 oC/ 2.03 MPa, and 230 oC/ 3.00 MPa for 2 min. treatment time. Significant changes in the colour, smell, and mechanical properties of the samples were observed after the treatment. Scanning electron microscope (SEM) images revealed changes in the surface morphology of the OPMF after the pretreatment. The degradation of hemicelluloses and changes in the functional groups of the lignocellulosic components were identified using Fourier Transform Infrared (FTIR) and Thermogravimetric (TG) analysis. These results suggest that HPST is a promising method for the pretreatment of OPMF.

Effect of high-pressure steam treatment on enzymatic saccharification of oil palm empty fruit bunches

The effectiveness of high-pressure steam treatment (HPST) with various treatment temperatures (170, 190, 210, and 230 °C) on the enzymatic hydrolysis yield of oil palm empty fruit bunches (OPEFB) was successfully investigated. Analysis of the compositions of raw and treated OPEFB showed that significant changes occurred after the HPST was performed. Scanning electron microscopy (SEM) analysis showed that the treated OPEFB gave better results in removing the silica bodies as compared to the untreated OPEFB. This analysis was in agreement with FTIR results, which revealed a significant decrease in the content of hemicelluloses after HPST. During saccharification, the amount of sugar produced was higher for treated OPEFB than untreated OPEFB. Thus, the results suggest that HPST can be applied as an alternative treatment method for the alteration of OPEFB structure and to enhance the digestibility of the biomass, therefore improving enzymatic hydrolysis.

Potential use of high-temperature and low-temperature steam treatment, sodium hydroxide and an enzyme mixture for improving the nutritional value of sugarcane pith

The effectiveness of different treatment methods to improve the nutritional value of the sugarcane byproducts (pith or bagasse) has been evaluated. The treatment methods included a high-pressure steam treatment (HPST; 19 bar, 3 min), treating the products with sodium hydroxide, sulphuric acid plus an enzyme mixture, or low-temperature steam treatment (LTST) under different conditions. Gas production (GP), two-step in vitro digestibility (IVD) and in situ degradability (ISD) techniques were used to monitor the effectiveness of the treatments. HPST resulted in a significant increased in the total soluble sugar (TSS) content of unsteamed pith (USP), 20 vs. 123.75 mg/100 mL. Except for the enzyme treatment, the other treatments led to a significant improvement in the nutritional value of sugarcane by-products, as measured by the IVD method. LTST resulted in an increase in potential GP (B) at higher temperature, reaction time and amount of acid. The highest potential GP (110.92 mL/300 mg DM) was achieved under the conditions, 134 °C, 18 g acid/kg DM, 120 min, and the lowest (72.4 mL/300 mg DM) under the conditions, 121 °C, no acid, 40 min. In situ dry matter degradability (ISDMD) was unaffected by LTST. Dry matter digestibility results indicated that the optimal treatments for treating pith were HPST and NaOH, but that enzymes were ineffective. Furthermore, considering treatment cost (creating high-pressure are more expensive than low temperature treatments), potential environmental health problems and the relative improvement in the nutritional value of pith achieved by the LTST + acid method, compared to the HPST method (as measured using GP), these results suggested that the methods based on the use of LTST and acid (especially under harsher conditions), have the best potential to improve the nutritive value of sugarcane by-products.

Preparation and characterization of micro- and nano-fibrils from jute

In order to prepare micro- and nano-fibrils from jute, the binder has to be cleaned off. A new technique including chemical (room temperature alkaline, acid steam, and 80 °C alkaline) and physical (high pressure steam) treatments of natural fibers was developed. The effects of chemical and physical treatments on the morphological development of jute fibers from micro- to nano-scale were observed by using scanning electron microscopy (SEM). This novel natural fibers treatment technology has two advantages compared with others. One is the long strands of natural fibers keep their length by special acid steam treatment, but the traditional acid solution treatment makes the length of natural fibers short. Another one is the high pressure steam treatment that made jute fibers nano-fibrils. The thermal property of untreated and treated fibers was determined by using thermogravimetric analysis (TGA) which indicated that the thermal stability of the jute fibers was enhanced after treatments. The lignin acted as binder was mainly removed by analyzing solid residues using fourier transform infrared spectrometer (FTIR).

Recycling of Polyethylene Terephthalate Using High-pressure Steam Treatment

In this study, polyethylene terephthalate (PET) was broken into fine particles during high-pressure steam treatment without crushing or using acidic or alkaline catalysts and solvents. Scanning electron microscopy (SEM) images showed that PET was decomposed from the surface by the high-pressure steam. 1H NMR and CP/MAS 13C NMR spectra revealed that the molecular weight of PET gradually decreased to that of an oligomer with increasing the high-pressure steam treatment time, and then reacted to a monomer. Differential scanning calorimetry (DSC) showed a decrease in the glass transition temperature (Tg), crystallization temperature (Tc), and melting temperature (Tm). X-Ray diffraction (XRD) measurements indicated that crystallinity increased with high-pressure steam treatment time. Decomposed PET consisting of hydroxyl groups and carboxylic acid thus repolymerize into new products. This investigation showed that a PET recycling method can be established easily, which had no adverse effect on the environment.

Improvement in the Stretching Property of Paper Yarn by Shape Memorization Produced with High-pressure Steam Treatment

The demand for paper yarn has increased as a textile fabric because of its light weight and low static electricity. However, paper yarn wrinkles easily and its softness and stretching properties are low. So we attempted to improve the stretching property of paper yarn by the high-pressure steam method which could provide a shape memorization to cellulosic materials. The most suitable condition based on our finding was steaming at 170 °C for 2 min after soaking in 0.28 % NH3 aqueous solution. By this treatment, over 84 % of the number of twists of paper yarn was maintained while the strength decreased to 78 %. For the paper yarn twisted together with viscose rayon filament, the number of twists was maintained at 94 % at 120 °C for 2 min of steaming without pre-treatment while the strength decreased to 85 %. The most desirable stretching property was achieved by the multi-twisting at 400 r/m of ten paper yarns, followed by high-pressure steaming. X-ray diffraction and CP/MAS 13C-NMR revealed that the crystallinity was increased 2 %, and the width of cellulose micelle was much larger by high-pressure steaming. Iβ type rich crystals of Manila hemp cellulose were stable at the steaming condition, so little transformation of the crystal type was observed. However, the orientation of the crystal was slightly improved by high-pressure steaming. It was considered that the mechanism of permanent shape memorization was derived from some recombination of the hydrogen bonds in the crystal region. High-pressure steaming was effective in the shape memorization of cellulosic fabrics and then the method improved the stretching property of textile made of multi-twisted paper yarns.

Recycling of Polyurethane using High-pressure Steam Treatment

Recycling of Polyurethane using High-pressure Steam Treatment

Modeling and Numerical Analysis of an Atypical Convective Coal Drying Process

This work presents modeling and numerical simulation of batch convective coal drying in a deep packed bed after a high-pressure steam treatment (a part of the Fleissner coal drying process). The process is atypical, because ambient air is used to dry and cool hot particles, while usually, e.g., in the deep packed bed drying of biomaterials, hot air is contacting cold particles. Product-specific data (intraparticle mass transfer, gas–solids moisture equilibrium) for coal (here lignite) are taken over from literature. Available data on coal drying in packed beds of medium height are used for model validation. Then, the model is applied to the considered industrial process. The design point of the process is critically reviewed, and alternatives are developed by systematically simulating the influence of inlet air conditions (temperature, humidity, flow-rate) and coal particle size. This type of analysis is necessary for efficiently scheduling plant dryers, since coal particle size may change, and air inlet temperature and humidity are changing with the ambient conditions.

Compressive-Molding of Wood by High-Pressure Steam-Treatment: Part 1. Development of Compressively Molded Squares from Thinnings

We attempted to compressive-mold logs of sugi (Cryptomeria japonica D.Don) to squares, and to permanently fix the transformed shape. The transformation and fixation were successively conducted under high-temperature saturated steam atmosphere by a newly designed apparatus which was a combined pressure vessel and a press machine. The results are summarized as follows: (1) The logs were successively softened by steaming at 150°C, compressively molded to square, and fixed the transformed shape by steaming at 200°C in this apparatus. (2) The shape of square fixed by high-pressure steam-treatment did not recover to original log shape by water-soaking and boiling. The result shows that the high-pressure steaming is effective for permanent fixation of the transformed shape. (3) The condition for sufficient fixation of the compressive transformation was steaming at 220°C for 3min when a 15 cm of diameter and 10cm of length sugi-thinning was used as a specimen. (4) Inner stress within a compressed wood was gradually reduced during steaming and. finally, the stress was removed completely.