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1.
The quality changes and the concentrations of tocopherols and γ-oryzanol, during successive steps of rice bran oil refining (RBO), were studied. For this purpose, samples of crude, degummed, neutralized, bleached, dewaxed and deodorized RBO were taken from an industrial plant and analyzed. The moisture, pH, acidity, peroxide value and unsaponifiable matter, were determined. The fatty acid composition was evaluated by GC, and the concentrations of tocopherols and γ-oryzanol were determined using HPLC with fluorescence and UV–Vis detection, respectively. To identify γ-oryzanol components, fractions of the HPLC eluant were collected and analyzed using mass spectrometry. Oil refining reduced the peroxide value and acidity to 1 and 3% of the values obtained in crude RBO, respectively. The fatty acid composition were not significantly altered during refining. The concentrations of the tocopherols in RBO followed the order α > (β + γ) > δ. The total concentration of tocopherols was 26 mg/100 g, and remained practically unaltered during refining. Up to nine components were distinguished in γ-oryzanol. After collecting the elution fractions, up to six components were identified by electrospray mass spectrometry. Refining reduced the total concentration of γ-oryzanol to 2% of its initial value.  相似文献   

2.
Sawdust waste and rice-husk fibers, which are lignocellulosic materials, were assessed in terms of their fiber-matrix adhesion and dispersion in composites. Different types of adhesives were used. The mechanical and water absorption properties were investigated. Overall, for the produced composites, the incorporation of phenol-formaldehyde resin into sawdust–rice husk ethylene vinyl acetate composite resulted in the best mechanical properties. The superior reinforcing characteristics of phenol-formaldehyde resin were shown by scanning electron microscopy (SEM), which revealed better fiber-matrix adhesion. Water absorption tests revealed that the presence of the adhesives affected the amount of water absorbed.  相似文献   

3.
《分离科学与技术》2012,47(9):1186-1195
The suitable conditions were determined for the recovery of high-value antioxidative compound, γ-oryzanol, from low cost rice bran soapstock by-product of the rice bran oil industry. First, soapstock was saponified and was then dehydrated and extracted with ethyl acetate. The extract was further purified by crystallization twice in appropriate solvent systems. At the most suitable conditions, using 20% v/v of ethyl acetate in methanol, and at 30°C and 1 h for the first crystallization step, and 5°C and 24 h for the second, the yield and purity of γ-oryzanol were 55.17 ± 0.59 wt% and 74.60 ± 4.12 wt%, respectively.  相似文献   

4.
This article comprises 4 yr of field experiments on methane (CH4) emissions from rice fields conducted at Los Baños, Philippines. The experimental layout allowed automated measurements of CH4 emissions as affected by water regime, soil amendments (mineral and organic), and cultivars. In addition to emission records over 24 h, ebullition and dissolved CH4 in soil solution were recorded in weekly intervals. Emission rates varied in a very wide range from 5 to 634 kg CH4 ha–1, depending on season and crop management. In the 1994 and 1996 experiments, field drying at midtillering reduced CH4 emissions by 15–80% as compared with continuous flooding, without a significant effect on grain yield. The net impact of midtillering drainage was diminished when (i) rainfall was strong during the drainage period and (ii) emissions were suppressed by very low levels of organic substrate in the soil. Five cultivars were tested in the 1995 dry and wet season. The cultivar IR72 gave higher CH4 emissions than the other cultivars including the new plant type (IR65597) with an enhanced yield potential. Incorporation of rice straw into the soil resulted in an early peak of CH4 emission rates. About 66% of the total seasonal emission from rice straw-treated plots was emitted during the vegetative stage. Methane fluxes generated from the application of straw were 34 times higher than those generated with the use of urea. Application of green manure (Sesbania rostrata) gave only threefold increase in emission as compared with urea-treated plots. Application of ammonium sulfate significantly reduced seasonal emission as compared with urea application. Correlation between emissions and combined dissolved CH4 concentrations (from 0 to 20 cm) gave a significant R2 of 0.95 (urea + rice straw), and 0.93 (urea + Sesbania), whereas correlation with dissolved CH4 in the inorganically fertilized soils was inconsistent. A highly significant correlation (R2 =0.93) existed between emission and ebullition from plots treated with rice straw. These findings may stimulate further development of diagnostic tools for easy and reliable determination of CH4 emission potentials under different crop management practices.  相似文献   

5.
《分离科学与技术》2012,47(3):671-681
Abstract

Response surface methodology (RSM) was applied to predict optimum conditions for microwave‐assisted extraction (MAE) of flavonoid from Radix Astragali. A central composite design was used to monitor the effect of temperature, extraction time, solvent‐to‐material ratio, and the ethanol concentration on yield of total flavanoid (TFA). Optimum extraction conditions were predicted as 108.2°C, 26.7 min, 23.1 ml/g solvent‐to‐material ratio and 86.2% ethanol. The maximum yield 1.234±0.031 mg/g was close to the yield of Soxhlet and higher than that of ultrasound assisted extraction and heat reflux extraction. MAE was an effective alternative to conventional extraction methods.  相似文献   

6.
7.
γ-Oryzanols of North American Wild Rice (Zizania palustris)   总被引:1,自引:0,他引:1  
γ-Oryzanol, a natural mixture of ferulic acid esters of triterpene alcohols and sterols, are an important bioactive components present in rice bran oil. In light of the recent increase in the popularity of wild rice among consumers, and the possibility of a direct relationship between γ-oryzanol composition and its bioactivity, the oryzanol profile of major wild rice (Zizania palustris) grown in North America was studied and compared to regular brown rice (Oryza sativa L.). A total of twenty-three γ-oryzanol components were separated, identified and quantified by HPLC coupled to an Orbitrap MS. The distribution of individual γ-oryzanols was similar for all the wild rice but significantly different from those of the regular brown rice. Unlike in the regular brown rice, a significant amount of steryl caffeate and cinnamate were found in the wild rice samples. Generally, the amounts of γ-oryzanol in the wild rice were higher compared to the regular brown rice, 1,352 vs. 688 μg/g. The results from this study showed that wild rice had a more diverse γ-oryzanol composition and the higher amounts compared to the regular brown rice.  相似文献   

8.
Metacaspases, a class of cysteine-dependent proteases like caspases in animals, are important regulators of programmed cell death (PCD) during development and stress responses in plants. The present study was focused on comprehensive analyses of expression patterns of the rice metacaspase (OsMC) genes in response to abiotic and biotic stresses and stress-related hormones. Results indicate that members of the OsMC family displayed differential expression patterns in response to abiotic (e.g., drought, salt, cold, and heat) and biotic (e.g., infection by Magnaporthe oryzae, Xanthomonas oryzae pv. oryzae and Rhizoctonia solani) stresses and stress-related hormones such as abscisic acid, salicylic acid, jasmonic acid, and 1-amino cyclopropane-1-carboxylic acid (a precursor of ethylene), although the responsiveness to these stresses or hormones varies to some extent. Subcellular localization analyses revealed that OsMC1 was solely localized and OsMC2 was mainly localized in the nucleus. Whereas OsMC3, OsMC4, and OsMC7 were evenly distributed in the cells, OsMC5, OsMC6, and OsMC8 were localized in cytoplasm. OsMC1 interacted with OsLSD1 and OsLSD3 while OsMC3 only interacted with OsLSD1 and that the zinc finger domain in OsMC1 is responsible for the interaction activity. The systematic expression and biochemical analyses of the OsMC family provide valuable information for further functional studies on the biological roles of OsMCs in PCD that is related to abiotic and biotic stress responses.  相似文献   

9.
Hybrid composites of rice straw (Rs)/seaweed (Sw) and polypropylene (PP) were prepared at a fixed filler ratio of 30:70 and variable ratio of the two reinforcements, viz. 30:0, 25:5, 20:10, 10:20, 0:30 by weight. Mechanical properties of the composites such as tensile strength (TS), bending strength (BS), impact strength (IS) and elongation at break (Eb%) were investigated and the composite formulation of 20:10:70 (Rs:Sw:PP) was found to be optimum that showed TS = 2.8 MPa, BS = 68 N/mm2, IS = 2.5 kJ/mm2 and Eb = 50%. For better compatibility, Rs and Sw were subjected to surface treatment using various intensities of γ-radiation to prepare improved hybrid composites. γ-irradiated filler hybrid composites significantly enhanced mechanical properties and the composite in which fillers were irradiated at 100 krad achieved maximum enhancement with TS = 35 MPa, BS = 75 N/mm2, IS = 2.7 kJ/mm2 and Eb = 68%. Water absorption capacity of the different composites was also studied and irradiated filler composites showed less water uptake.  相似文献   

10.
11.
Wood–Ceramics are prepared from a shaped mixture of rice husk and high-temperature coal tar pitch by pyrolysis at different temperatures. Subsequently, the wood–ceramics are modified by pyrolysis of different mixture precursors with adding lignin. The effect of pyrolysis temperature, lignin content and lignin types on the microstructure, yield, volume shrinkage, open porosity ratio and bending strength of the wood–ceramics is discussed, respectively. The results show that the microstructure, volume shrinkage ratio, and bending strength of wood–ceramics are significantly dependent on the pyrolysis temperature, lignin content and types. When the pyrolysis temperature increases from 500 to 1200 °C, the (002) crystal planes peaks of the wood–ceramics move to a higher diffraction angle and the intensity of these peaks increase. The volume shrinkage ratio and bending strength of the wood–ceramics increase from 41.2 to 55.5 % and 10.2 to 31.2 MPa, respectively. Moreover, the open porosity ratio first decreases from 35.6 to 26.2 %, and then increases to 30.1 %. The enzymatic hydrolysis lignin (EHL) plays an important role in improving the order and graphitization, porous content and open porosity of the EHL-modified wood–ceramics, whereas the lignosulfonate causes the bending strength of the lignosulfonate-modified wood–ceramics to decrease.  相似文献   

12.
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16.
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17.
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18.
The paper describes the reaction between car-bon-containing refractories,magnesia-chrome re-fractories and matte,converter slag.The results show that carbon-containing refrctories have good resistance to matte and converter slag in nitrogen atmosphere,The practical results are unsuitable for nickel converter ,high performance magnesia chrome refractories are promising materials.Newly developed high quality direct bonding magnesia chrome,rebonded co-clinker magnesia chrome,fused cast magnesia chrome used in nickel flash smelting furnaces are introduced briefly.  相似文献   

19.
Nacka F  Cansell M  Méléard P  Combe N 《Lipids》2001,36(12):1313-1320
Liposomes made from a natural marine lipid extract and containing a high polyunsaturated n−3 fatty lipid ratio were envisaged as oral route vectors and a potential α-tocopherol supplement. The behavior of vesicles obtained by simple filtration and of giant vesicles prepared by electroformation was investigated in gastrointestinal-like conditions. The influence of α-tocopherol incorporation into liposomes was studied on both physical and chemical membrane stability. Propanal, as an oxidation product of n−3 polyunsaturated fatty acids, was quantified by static headspace gas chromatography when α-tocopherol incorporation into liposome ratios ranged from 0.01 to 12 mol%. Best oxidative stability was obtained for liposomes that contained 5 mol% α-tocopherol. Compared to the other formulas, propanal formation was reduced, and time of the oxidation induction phase was longer. Moreover, α-tocopherol induced both liposome structural modifications, evidenced by turbidity, and phospholipid chemical hydrolysis, quantified as the amount of lysophospholipids. This physicochemical liposome instability was even more pronounced in acid storage conditions, i.e., α-tocopherol incorporation into liposome membranes accelerated the structural rearrangements and increased the rate of phospholipid hydrolysis. In particular, giant vesicles incubated at pH 1.5 underwent complex irreversible shape transformations including invaginations. In parallel, the absorption rate of α-tocopherol was measured in lymph-cannulated rats when α-tocopherol was administrated, as liposome suspension or added to sardine oil, through a gastrostomy tube. α-Tocopherol recovery in lymph was increased by almost threefold, following liposome administration. This may be related to phospholipids that should favor α-tocopherol solubilization and to liposome instability in the case of a high amount of α-tocopherol in the membranes. A need to correlate results obtained from in vitro liposome behavior with in vivo lipid absorption was demonstrated by this study.  相似文献   

20.
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