Journal of Oleo Science
Online ISSN : 1347-3352
Print ISSN : 1345-8957
ISSN-L : 1345-8957
最新号
選択された号の論文の18件中1~18を表示しています
Review
Oils and Fats
  • Shunian Luo, Yang Song, Ruiying Wang, Jing Yao, Yajie Dai, Jun Chen, D ...
    2021 年 70 巻 10 号 p. 1357-1366
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    A homemade nanonickel catalyst was made by the ultrasonic liquid-phase reduction method, characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and applied to the isomerization reaction of high linoleic acid sunflower oil. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analysis showed that the homemade nickel particles were spherical, uniformly dispersed, less agglomerated, 20 to 75 nm in size, and nanoscale nickel powder. Compared with commercially available Raney nickel, the homemade nanonickel powder has a larger specific surface area, smaller pore size and higher catalytic activity. The X-ray diffraction spectrum of the homemade nanonickel powder had distinct diffraction peaks at its characteristic peaks which indicated that the powder was pure nickel. The nanometal nickel particles are fully dispersed in high oleic sunflower oil under the action of ultrasound. The results showed that it could effectively reduce the activation reaction time of nanonickel, and the conversion rate of conjugated linoleic acid could reach 86.24%. The process of activating the catalyst is omitted, the number of times of repeated uses of the nanonickel catalyst is increased, and the environmental pollution of the production is avoided. To obtain sunflower oil rich in CLA, it also provides a new idea for the preparation of conjugated linoleic acid.

  • Amna Zulqarnain, Arjumand Iqbal Durrani, Hina Saleem, Saima Rubab
    2021 年 70 巻 10 号 p. 1367-1372
    発行日: 2021年
    公開日: 2021/10/05
    ジャーナル オープンアクセス

    Beautiful green leaves of Papaya are the rich source of Chlorophyll. Green color of chlorophyll has been used for a very long time as a natural colorant. Carica papaya has been considered as a good example and reasonable source of natural phytochemicals, which makes it suitable to color the food items and beverages. The aim of the present investigation is to develop the process of ultrasonic extraction in combination with solid phase extraction (SPE) to extract out chlorophyll with high yield as well as high degree of clarity. Newly customized ultrasonic-assisted extraction technique for the extraction of chlorophyll from Carica papaya leaves is optimized by taking different parameters like time, temperature, solvents concentrations, and raw material under consideration. Furthermore, the extract was purified by means of SPE and examined by using UV-Vis spectrophotometer. The highest yield of chlorophyll (dye) extract was found as 40% in solvent solution having 80 mL of ethanol and 20 mL of water with 5 minutes of extraction time, 35°C of temperature, and 1 grams of raw material in the sonication bath. Furthermore, the SPE purified sample was characterized by means of the UV-Vis spectrophotometer and here the total chlorophyll content was 34 mg/g, including chlorophyll a with a concentration of 14.1246 mg/g and chlorophyll b with concentration of 19.845 mg/g respectively. Consequently, sonication method can be suggested as a good method to get better concentration of chlorophyll.

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  • Lirong Xu, Xue Mei, Jiarui Chang, Gangcheng Wu, Qingzhe Jin, Xingguo W ...
    2021 年 70 巻 10 号 p. 1373-1380
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス
    電子付録

    Fourier transform infrared (FTIR) spectroscopy combined with backpropagation artificial neural network (BP-ANN) were utilized for rapid and simultaneous assessment of the lipid oxidation indices in French fries. The conventional indexes (i.e. total polar compounds, oxidized triacylglycerol polymerized products, oxidized triacylglycerol monomers, triacylglycerol hydrolysis products, and acid value), and FTIR absorbance intensity in French fries were determined during the deep-frying process, and the results showed the French fries had better quality in palm oil, followed by sunflower oil, rapeseed oil and soybean oil. The FTIR spectra of oil extracted from French fries were correlated to the reference oxidation indexes determined by AOCS standard methods. The results of BP-ANN prediction showed that the model based on FTIR fitted well (R2 > 0.926, RMSEC < 0.481) compared with partial least-squares model (R2 > 0.876). This facile strategy with excellent performance has great potential for rapid characterization quality of French fries during frying.

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  • Kazuki Matsuo, Satoru Ueno
    2021 年 70 巻 10 号 p. 1381-1390
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス
    電子付録

    This paper reports the preparation of oleogels composed of edible oils (olive oil, squalene, and caprylic/capric triglyceride) and high-melting fat crystals (tribehenoyl-glycerol (BBB)) to explore the potential use of BBB/edible oil mixtures as low-cost and stable gelators. These mixtures exhibited gel-like behaviors upon rapid cooling and subsequent heating. The mixtures of BBB in the liquid oils formed oleogels at BBB concentrations > 4.0 wt%. The thermal behaviors, crystal structures, and crystal morphologies of mixtures of BBB produced from 6.0 wt% BBB crystals in 94.0 wt% liquid oils were examined following the treatment of these systems according to different temperature regimes. In addition, rheological analysis was conducted to evaluate the physical properties and storage stabilities of the prepared oleogels. It was found that rapid cooling to the crystallization temperature (Tc) from 70°C and subsequent heating to the final temperature (Tf) were necessary to reveal the gel-like behavior. In addition, the crystals treated with rapid cooling were smaller and more uniform in size than those treated with a simple cooling procedure. The differential scanning calorimetry melting peaks were broad or split, and exhibited the eutectic mixing behavior of multi-component triacylglycerols. The X-ray diffraction spectra showed that the melt-mediated α to β transformation of the mixtures was a prerequisite for revealing the gel-like behavior. Moreover, the tempering procedure was found to influence the physical properties of the oleogels, wherein no visible changes were observed for any of the oleogels after rapid cooling and storage for 6 months at 25°C.

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Detergents, Surfactants, Interface and Colloid
  • Chun-Wei Wang, Ming-Chen Chuang, Chieh-Yi Chang, Chien-Hsiang Chang, Y ...
    2021 年 70 巻 10 号 p. 1391-1401
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス
    電子付録

    Lipid-like pseudo-double-chained catanionic surfactants have emerged as the attractive materials to prepare potential vesicular carriers in drug and gene delivery applications. In particular, the semi-spontaneous process has been developed to fabricate ethosome-like catanionic vesicles for the transdermal drug delivery. In this work, Arbutin (a water-soluble drug) encapsulation efficiency of ethosome-like catanionic vesicles fabricated from decyltrimethylammonium-tetradecylsulfate (DeTMA-TS, CH3(CH2)9 N(CH3)3-CH3(CH2)13SO4) and decyltrimethylammonium-dodecylsulfate (DeTMA-DS, CH3(CH2)9N(CH3)3-CH3(CH2)11SO4) with various amounts of ethanol and cholesterol in tris buffer solution was experimentally determined. A simple unilamellar vesicle (ULV) model, resulting in the theoretical encapsulation efficiency within ±10% error for most vesicle compositions, was also developed. Such agreement indirectly confirmed the formation of unilamellar vesicles by the preparation method. Stable ethosome-like catanionic vesicles by using catanionic surfactants with the aid of suitable amounts of ethanol and cholesterol, which led to polydispersity index (PDI) values of vesicle size distribution less than 0.3, were successfully prepared and their hydrophilic drug encapsulation efficiencies can be accurately predicted. Furthermore, the linear correlations of the trap volume ratio with both vesicle size and concentration of the extra added CHOL also provide important guidelines for controlling the drug loading of ethosome-like catanionic vesicles. The accomplishments reached for the novel vesicles are useful for developing their transdermal drug delivery applications.

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  • Taghreed S. Alnusaire
    2021 年 70 巻 10 号 p. 1403-1416
    発行日: 2021年
    公開日: 2021/10/05
    ジャーナル オープンアクセス

    The present study was aimed to prepare and evaluated solid lipid nanoparticles (SLNs) of olive leaves extract powder (OLP) which contained many anti-oxidant and antimicrobial agents like oleuropein, a natural polyphenol. The major issue concern OLP was the instability due to environmental conditions and hence compromised bioactivity. To overcome this problem, SLNs were designed by hot homogenous followed by sonication technique to protect the drug and improve its antioxidant and antimicrobial activity. Lipids like compritol 888ATO and surfactant like tween 80 were used for the development and stabilization of SLNS and optimization was done by Box-Behnken statistical design (3x3). The optimized batch (F9) showed particle size, entrapment efficiency, PDI, and zeta potential 277.46 nm, 80.48%, 0.275, and -23.18 mV respectively. Optimized formulation (F9) exhibited a sustained release pattern up to 24 h with first-order release kinetic (R2 = 0.9984) and the mechanism of drug release was found to be Fickian diffusion type (n = 0.441). Upon the stability study, it could be found that SLNs formulation was stable. Anti-oxidation and anti-microbial studies were conducted on optimized formulation and findings suggested that SLNs showed an improved radical scavenging activity and anti-microbial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria. Finally, it was concluded that developed SLNs were able to protect and suitable for the delivery of OLP.

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Biochemistry and Biotechnology
  • Nkosinathi E. Madlala, Andrew C. Eloka-Eboka, David Lokhat
    2021 年 70 巻 10 号 p. 1417-1427
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    Improvements on energy density of loose biomass such as sugarcane feedstock is crucial in the technology of biomass energy conversion and generation. South Africa is one of the producers and refiners of sugarcane. High energy density of sugarcane bagasse biomass through separation and briquetting is imperative in developing adequate streams and quality energy generation from sugarcane upstream milling processes. Unseparated bagasse and separated fractions of fiber and pith possess energy contents of about: 16.14 MJ/kg, 17.73 MJ/kg and 15.74 MJ/kg respectively. Fiber fractions have high energy content than bagasse and pith which demonstrates that pith fraction from bagasse lowers energy density. However, the use of starch and PVA (Polyvinyl Alcohol) as binders during briquetting contributed no significant difference in the overall energy density of the biomass briquettes produced. In the same vein, the addition of 50% charcoal as the hybrid component significantly improves the energy density and the physical properties of briquettes, biomass fractions of bagasse, fiber and pith to: 19.43 MJ/kg, 19.57 MJ/kg and 18.37 MJ/kg respectively. Fiber fraction remains the biomass fraction with highest energy content as compared to other fractions. After briquetting and drying of briquettes to moisture content below 12%, there was a significant improvement on the burning rate, briquetting, binder, hybridization which does improve the biomass briquettes characteristics. Separation of bagasse is crucial under certain conditions since there are no significance differences in the energy density of bagasse fractions. However, the use of PVA and charcoal does pose the necessity of bagasse separation from its fractions for briquetting.

  • Yue-Wen Chang, Wen-Jun Zhu, Wei Gu, Jun Sun, Zhi-Qiang Li, Xiao-En Wei
    2021 年 70 巻 10 号 p. 1429-1435
    発行日: 2021年
    公開日: 2021/10/05
    ジャーナル オープンアクセス

    Recently, the Populus yunnanensis extract has drawn the attention of most researchers, because of their anti-cancer activity. In this present research, the anti-cancer activity of the Populus yunnanensis extract was measured with Cell Counting Kit-8 (CCK-8) detection kit on the cancer cells. Then, the inhibitory activity of the Populus yunnanensis extract on the migration and invasion ability of the cancer cells was also determined in this present research with trans-well assay. Subsequently, to reveal the evolutionary genome evolution evaluation of the Populus yunnanensis and other Populus species, the high-throughput Illumina pair-end sequencing was performed and the chloroplast (cp) genome of Populus yunnanensis was determined, and the phylogenetic analysis was finished as wells. The results of the CCK-8 assay indicated that the Populus yunnanensis extract showed inhibitory effect on the cancer cell viability. Besides, the migration and invasion ability of the cancer cell was also reduced by the Populus yunnanensis extract. The complete chloroplast genome sequence results revealed that the Populus yunnanensis has a 156,505 bp circular cp genome. The phylogenetic analysis further revealed that the Populus yunnanensis has closely relationship with Populus simonii.

  • Fadzil Noor Gonawan, Puteri Norathirah Megat Abu Bakar, Azlina Harun K ...
    2021 年 70 巻 10 号 p. 1437-1445
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    The Lipase-catalyzed synthesis of glyceryl monocaffeate (GMC) in choline chloride-urea of natural deep eutectic solvent (NADES) media is reported to provide amphiphilic character to caffeic acid (CA). The modification of CA into GMC could potentially increase its solubility and widen the application of CA’s biological activities in water and oil-based systems. The high conversion was achieved when the reaction was carried out with the addition of more than 20 %v/v water, at a high molar ratio of glycerol and 40°C. It was found that the lipase-catalyzed transesterification of ethyl caffeate (EC) and glycerol in choline chloride-urea of DES media obeyed ping-pong bi-bi mechanism with Vmax = 10.9 mmol.min-1, KmEC = 126.5 mmol and KmGly = 1842.7 mmol.

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  • Laizeng Yu, Ruihua Gao, Xuewen Song, Xuechao Li, Jiacheng Zhu
    2021 年 70 巻 10 号 p. 1447-1459
    発行日: 2021年
    公開日: 2021/10/05
    ジャーナル オープンアクセス

    Cardiovascular disease (CVD) is a chronic disease and causes the highest rate of death globally. CVD-related deaths account for 80% of all deaths in low and middle-income countries, such as China. Crocetin (CT), a carotenoid phytoconstituent already confirm their anti-inflammatory and antioxidant effects in various diseases animal models. In the study, we make effort to access the cardio-protective effect of Crocetin against vitamin D3 and high fat induced atherosclerosis in rats and scrutinize the underlying mechanism. Sprague Dawley (SD) rats were used in this study and rats were divided into different groups and high fat diet and vitamin D was used for induction the atherosclerosis. The rats were received oral administration of crocetin (5, 10 and 15 mg/kg) and simvastatin (0.5 mg/kg) until 30 days. At the end of the experimental period, lipid, cardiac markers, anti-inflammatory, antioxidant, pro-inflammatory cytokines and atherogenic index were estimated. The mRNA expression of Intercellular adhesion molecule-1 (ICAM-1), Monocyte Chemoattractant Protein-1 (MCP-1) and vascular cell adhesion molecule 1 (VCAM-1) in aortic tissue of the atherosclerotic rats. Crocetin significantly reduced the aortic membrane thickness and platelet aggregation rates. Crocetin also dose-dependently reduced total cholesterol (TC), very low-density lipoprotein (VLDL), triacylglycerol (TG), low-density lipoprotein (LDL) and augmented the level of high-density lipoprotein (HDL) level. Additionally, Crocetin significantly (p < 0.001) abridged the level of malonaldehyde (MDA) and augmented the level of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione peroxidase (GPx). Furthermore, Crocetin significantly (p < 0.001) dose-dependently reduced the levels of pro-inflammatory cytokines and inflammatory mediators. Crocetin attenuated mRNA expression of VCAM-1, ICAM-1 and MCP-1. Crocetin had anti-atherosclerosis and cardio-protective effects on vitamin D3 and high fat induced atherosclerosis in rats through anti-inflammatory and antioxidant mechanisms.

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Nutrition and Health Function
  • Shigesaburo Ogawa, Haruka Katsuragi, Katsuya Iuchi, Setsuko Hara
    2021 年 70 巻 10 号 p. 1461-1467
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス
    電子付録

    The precise understanding of the behaviour of vitamin E (α-tocopherol; Toc) complexed with cyclodextrin (CD) additives in aqueous solution is a fundamental issue for further development of their aqua-related biological applications. In this study, the solubilisation and complexation behaviours of Toc with methyl-substituted CD derivatives and the radical scavenging ability of the resulting complexes were precisely investigated in water media. Several problems were encountered upon pre-dissolving Toc in an organic solvent prior to the addition to the water media, such as enhancement of the dispersibility and decrease in the complexation capacity. Additionally, dispersions were obtained in some cases when mixing CD and Toc even in the absence of an organic solvent; therefore, to perform the measurements, a transparent solution was prepared via filtration with a nanopore filter. Consequently, unexpectedly, the addition of certain CD methylated derivatives did not always enhance the solubility of Toc significantly. However, 2,6-di-O-methylated β-CD (2,6-DMCD) formed a water-soluble inclusion complex with Toc, effectively enhancing its solubility. A phase solubility study indicated the formation of 1:2 or 1:3 Toc/CD inclusion complexes, and the interaction of 2,6-DMCD with both the chromanol head and the phytol chain of Toc was revealed by 2D ROESY nuclear magnetic resonance analysis. The interaction between 2,6-DMCD and the chromanol head was also confirmed for a 2,6-DMCD-2,2,5,7,8-pentamethyl-6-chromanol inclusion complex. Additionally, a rapid scavenging effect for molecularly dissolved Toc was demonstrated even in a system comprising a chromanol head directly encapsulated by CD. Hence, this work elucidated the precise complexation and radical scavenging ability of 2,6-DMCD-Toc in an aqueous solution, which paves the way for its biological applications.

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  • Ryota Hosomi, Anna Matsudo, Koki Sugimoto, Takaki Shimono, Seiji Kanda ...
    2021 年 70 巻 10 号 p. 1469-1480
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス
    電子付録

    Dietary fish oil containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been reported to affect the diversity and composition of gut microbiota and bacterial metabolites. However, few reports have focused on the effects of EPA and DHA on gut microbiota diversity and bacterial metabolites. This study evaluated the effects of dietary EPA-ethyl ester (EE) and DHA-EE on steroid metabolism, gut microbiota, and bacterial metabolites in Wistar rats. Male rats were fed the experimental diets containing 5% (w/w) soybean oil-EE (SOY diet), EPA-EE (EPA diet), and DHA-EE (DHA diet) for four weeks. The lipid contents in the serum and liver, mRNA expression levels in the liver, and the diversity, composition, and metabolites of the gut microbiota were evaluated. The EPA and DHA diets decreased serum and liver cholesterol contents compared to the SOY diet. In addition, there were no significant changes in gene expression levels related to steroid metabolism in the liver between the EPA and DHA groups. Rats fed the DHA diet had lower microbiota diversity indices, such as Simpson and Shannon indices, than rats fed the SOY and EPA diets. In addition, rats fed EPA and DHA had significant differences in the relative abundance of microbiota at the genus level, such as Phascolarctobacterium, Turicibacter, and [Eubacterium]. Therefore, it was concluded that EPA and DHA have different effects on the diversity and composition of gut microbiota under the experimental conditions employed herein.

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Essential Oils and Natural Products
  • Fang-Xiang Xu, Jing-Yu Zhang, Jing Jin, Zu-Guang Li, Yuan-Bin She, Maw ...
    2021 年 70 巻 10 号 p. 1481-1494
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    In the past decade, natural deep eutectic solvents (NADESs) as green and sustainable extraction solvents with great potential for the efficient extraction of bioactive compounds from the plants are emerging. In this study, a microwave-assisted technology is used to prepare natural deep eutectic solvents. And natural deep eutectic solvents as pretreatment solvents coupled with microwave-assisted hydrodistillation (MAHD) for isolating essential oil (EO) derived from turmeric (Curcuma longa L.) is investigated. To improve the essential oil yield of turmeric (Curcuma longa L.) as a target, various factors affecting extraction efficiency including the type and amount of natural deep eutectic solvents, pretreatment time, pretreatment temperature and hydrodistillation (HD) time are discussed and optimized through central composite design (CCD) of the response surface methodology (RSM). The optimal conditions are as follows: natural deep eutectic solvent composed of choline chloride and oxalic acid (molar ratio with 1:1) as a pretreatment solvent, an amount of 60 g, a pretreatment time of 5 min, a pretreatment temperature of 84 ºC, a hydrodistillation time of 76 min. Under the optimum conditions, the highest essential oil yield of 0.85% is achieved. Additionally, the essential oil is analyzed by using gas chromatography-mass spectrometry (GC-MS), with a total of 49 compounds being identified. Through combining natural deep eutectic solvents with a microwave-assisted hydrodistillation technique, this work provides an eco-friendly extraction way of isolating essential oil, which boosts development in the monitoring other spice quality field.

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General Subjects
  • Iwona Szymańska, Anna Żbikowska, Malgorzata Kowalska, Krzysztof Golec
    2021 年 70 巻 10 号 p. 1495-1507
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    The purpose of this study was to determine the impact of the fat system type (milk fat - MF, palm oil - PO or oleogel - OG, i.e. RO-LO - rapeseed oil and linseed oil mixture structured by candelilla wax) on the properties of soy creams, in comparison with dairy cream. The MF exhibited the most increase of acid value (2.5-fold), and the RO-LO - increase of peroxide value (3-fold), after 30 days of storage at 20°C. The PO was the most oxidative stable. The OG presented the slightest oxidative changes, the highest slip melting point (39°C) and centrifugal stability (99.6%). The pH and total acidity values of soy creams were similar to soy drink. All creams exhibited unimodal distribution of dispersed particles. The average particle size and dispersity indexes of these emulsions were in range of 1.74-1.80 µm and 0.93-1.16, respectively. The creams with MF or OG exhibited a greater viscosity than sweet dairy cream - 1.66 10-5 nm-2, and a higher degree of shear-thinning. The accelerated creaming phenomenon (flotation of lipids molecules) occurred during centrifugation. The cream with PO had the lowest resistance to centrifugal force (instability index - 0.052). The possibility to obtain a stable vegan soy creams containing oleogel (as replacer of conventional fats) has been demonstrated.

  • Muhammad Nurdin, Haznan Abimanyu, Abdul Haris, Maulidiyah Maulidiyah, ...
    2021 年 70 巻 10 号 p. 1509-1515
    発行日: 2021年
    公開日: 2021/10/05
    ジャーナル オープンアクセス

    Many studies have explored the pretreatment of lignocellulosic biomass based on oil palm empty fruit bunch (OPEFB) which is categorized as potential biomass waste for bioethanol production. Before proceeding further to obtain bioethanol, several steps such as pretreatment to increase organic constituents are needed. The ionic liquids (ILs) were commonly investigated by many researchers for lignocellulosic pretreatment because it is easy solubilization property, non-toxic, and not harmful impacts on the environment. Therefore in this study, the hypothesis and main objective were to observe the effectiveness of triethylammonium methanesulfonate ion liquid (TMS IL) in the OPEFB lignocellulose pretreatment process. Three variations were studied to obtain optimization of the pretreatment process, such as times duration, IL composition, and temperature. Based on these results, we observed the effectiveness of the time duration for OPEFB pretreatment of 20 hours. Furthermore, it was applied to determine the optimization of IL composition and temperature showing that using 91% (1:1:10) at 120°C for 20 hours has provided good performance for the OPEFB lignocellulose pretreatment process. TMS IL has exhibited the ability to reduce hemicellulose and lignin contents to 7.35% and 17.80%, whereas cellulose was increased by 54.24%. This has the opportunity to be projected to a larger scale for bioethanol production based on OPEFB lignocellulose.

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  • Daisuke Sakemi, Satoshi Horikoshi
    2021 年 70 巻 10 号 p. 1517-1525
    発行日: 2021年
    公開日: 2021/10/05
    [早期公開] 公開日: 2021/09/08
    ジャーナル オープンアクセス

    The origin of the specific effect of microwaves on chemical reactions (the microwave effect) was investigated by examining the effect of microwaves on small groups of molecules such as clusters. The origin of the effect was verified by introducing 2.45 GHz microwaves into a system equipped with a supersonic molecular jet and a special microwave feedthrough to record the fluorescence excitation spectrum of molecules. The carrier gas was bubbled through water and introduced into a phenol-filled sample holder to generate phenol-water clusters. Subsequently, it was confirmed that exposure of the phenol-water clusters contained in the molecular jet ejected from the pulse valve to microwave radiation increased the fluorescence derived from the phenol monomer. This is considered to occur because the phenol-water clusters in the molecular jet absorb microwaves and collapse, thereby increasing the abundance of phenol monomers. This result suggests that microwaves affect not only bulk systems but also small groups of molecules, and that local selective heating, which is one of the causes of the microwave effect, may occur.

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