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Minor constituents of vegetable oils during industrial processing 总被引:6,自引:10,他引:6
R. Ap. Ferrari E. Schulte W. Esteves L. Brühl K. D. Mukherjee 《Journal of the American Oil Chemists' Society》1996,73(5):587-592
We report the effects of individual steps of industrial refining, carried out in Brazil, on the alteration of selected minor
constituents of oils, such as corn, soybean, and rapeseed oils. Total sterols, determined by capillary gas chromatography
(GC), decreased by 18–36% in the fully refined oils, compared with the crude oils. The total steradienes, dehydration products
of sterols, were determinedvia a simple clean-up on a short silica gel column, followed by high-performance liquid chromatography (HPLC) with ultraviolet
detection. The level of steradienes, normally not present in crude oils, increased after each refining step, especially after
deodorization. Thus, the content of steradienes increased after deodorization by about 15- to 20-fold in corn and soybean
oils, and by about 2-fold in rapeseed oil. The total steryl esters were also determinedvia clean-up on a short silica gel column, followed by HPLC with evaporative light scattering mass detection. A minor decrease
in the level of steryl esters was observed after complete refining. The individual tocopherols and tocotrienols were determined
by HPLC with a fluorescence detector. The level of total tocopherols and tocotrienols decreased by about 2-fold after complete
refining of corn oil and by about 1.5-fold in soybean and rapeseed oils. In all three cases, maximum reduction of tocopherols
was observed after the deodorization step. The level of polymeric glycerides, determinedvia clean-up on a short silica gel column followed by size-exclusion HPLC, increased to some extent (0.4–1%) during refining.
The level oftrans fatty acids, determined by capillary GC, also increased to a substantial extent (1–4%) after refining.
Part of doctoral thesis of Roseli Ap. Ferrari to be submitted to Faculdade de Engenharia de Alimentos, Universidade de Campinas,
Campinas, Brazil. 相似文献
3.
A. M. Nash T. L. Mounts W. F. Kwolek 《Journal of the American Oil Chemists' Society》1983,60(4):811-814
Ultratrace levels of nickel, chromium, copper and iron occurring in hydrogenated vegetable oil products were estimated by dispersion of the samples in 4 methyl-2-pentanone and atomic absorption analysis by the graphite furnace technique. The principal goals in establishing the analytical methods were improved sensitivity to metals at low levels and applicability to limited amounts of products. Using reproducibility and linearity of response as criteria, optimum oil concentration in solvent and instrument parameters were established. For a series of commercial products, the method of standard addi-tions was adopted to correct for matrix differences between the products and salad oil-based standards. The range for the metals was determined in five cooking oils: Ni, 29–207 ppb; Cr, 1–5 ppb; Cu, 13–37 ppb; and Fe, 138–301 ppb; in recovered oils from five margarines: Ni, 34–70 ppb; Cr, 2–12 ppb; Cu, 26–58 ppb; and Fe, 239–540 ppb; and in five solid shortenings: Ni, 592–2772 ppb; Cr, 8–35 ppb; Cu, 26–108 ppb. 相似文献
4.
Since the production cost of biodiesel is now the main hurdle limiting their applicability in some areas, catalytic cracking reactions represent an alternative route to utilization of vegetable oils and animal fats. Hence, catalytic transformation of oils and fats was carried out in a laboratory-scale two-stage riser fluid catalytic cracking (TSRFCC) unit in this work. The results show that oils and fats can be used as FCC feed singly or co-feeding with vacuum gas oil (VGO), which can give high yield (by mass)of liquefied petroleum gas (LPG), C2-C4 oletms, tor example 45% LPG, 47% C2-C4 olefins, and 77.6% total liquid yield produced with palm oil cracking. Co-feeding with VGO gives a high yield of LPG (39.1%) and propylene (18.1%). And oxygen element content is very low (about 0.5%) in liquid products, hence, oxygen is removed in the form of H2O, CO and CO2. At the same time, high concentration of aromatics (C7-C9 aromatics predominantly) in the gasoline fraction is obtained after TSRFCC reaction of palm oil, as a result of large amount of hydrogen-transfer, cyclization and aromatization reactions, Additionally, most of properties of produced gasoline and diesel oil fuel meet the requirements of national standards, containing little sulfur. So TSRFCC technology is thought to be an alternative processing technology leading to production of clean fuels and light olefins. 相似文献
5.
High-oryzanol rice brain oil (HORBO), rice bran oil (RBO), and partially hydrogenated soybean oil (PHSBO) were used to prepare
french fries. Polar fractions of the three oils were analyzed for nonvolatile components by high-performance size-exclusion
chromatography (HPSEC) with ELSD. In all frying experiments, both HORBO and RBO yielded predominantly dimeric and monomeric
materials. The concentrations of polymeric species in HORBO and RBO were greater than in PHSBO. The major degradation products
from HORBO, RBO, and PHSBO were dimers (8.93 mg/100 mg oil), monomers (10.5 mg/100 mg oil), and DG (22.4 mg/100 mg oil), respectively.
Thermal degradation via hydrolysis was much greater in PHSBO than in HORBO or RBO. Distribution data indicated that the extent of polymer formation
from frying was in the order RBO>HORBO >PHSBO, consistent with the degree of lipid unsaturation and the oryzanol content in
these oils. HPSEC-ELSD results from the two RBO showed that the amounts of various polymeric species, including trimers and
higher polymers, were lower in HORBO than in RBO. The percentage of polar materials and the percentage of polymerized TG,
which were used as indicators of oil quality and stability, decreased with increasing tocopherol and oryzanol contents in
the order PHSBO>HORBO>RBO. 相似文献
6.
A series of polyurethanes from polyols derived from soybean, corn, safflower, sunflower, peanut, olive, canola, and castor oil were prepared, and their thermal stability in air and nitrogen assessed by thermogravimetric analysis, FTIR, and GC/MS. Oil‐based polyurethanes generally had better initial thermal stability (below 10% weight loss) in air than the polypropylene oxide‐based polyurethane, while the latter was more stable in nitrogen at the initial stage of degradation. If weight loss at a higher conversion is taken as the criterion of stability, then oil polyurethanes have better thermal stability both in air and in nitrogen. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1723–1734, 2000 相似文献
7.
Density and viscosity of vegetable oils 总被引:1,自引:5,他引:1
C. M. Rodenbush F. H. Hsieh D. S. Viswanath 《Journal of the American Oil Chemists' Society》1999,76(12):1415-1419
A generalized method was developed to estimate the liquid density of vegetable oils and fatty acids. The correlation for vegetable
oils was based on fatty acid critical properties and composition of the oil. The correlations predicted the density of vegetable
oils and fatty acids with an average absolute deviation of 0.21 and 0.77%, respectively. The present method is slightly more
accurate in predicting vegetable oil density and simpler than the method of Halvorsen et al. Also, a method is introduced that predicts viscosity from density data, thus relating two key properties of vegetable oils. 相似文献
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Bertrand W. Mathäus 《Journal of the American Oil Chemists' Society》1996,73(8):1039-1043
The oxidative stability of five different oils was determined by Rancimat analysis with conductivity and chemiluminescence
measurements for evaluation of the induction periods. Samples of oil, taken at intervals from the Rancimat apparatus, were
used for chemiluminescence measurements. The chemiluminescence results were plotted vs. time, and the resulting curves were
evaluated with a graphical tangential procedure in the same way as the curves of the Rancimat method (conductivity measurement).
Induction periods of the oils assessed by Rancimat and chemiluminescence methods showed a significant linear correlation (r=0.9865). The temperature dependence of the induction periods evaluated by chemiluminescence and by conductivity was investigated
with walnut oil. A marked temperature dependence was observed for both. 相似文献
10.
Analysis of free and esterified sterols in vegetable oils 总被引:2,自引:6,他引:2
T. Verleyen M. Forcades R. Verhe K. Dewettinck A. Huyghebaert W. De Greyt 《Journal of the American Oil Chemists' Society》2002,79(2):117-122
In vegetable oils, phytosterols occur as free sterols or as steryl esters. Few analytical methods report the quantification
of esterified and free sterols in vegetable oils. In this study, esterified and free sterols were separated by silica gel
column chromatography upon elution with n-hexane/ethyl acetate (90∶10 vol/vol) followed by n-hexane/diethyl ether/ethanol (25∶25∶50 by vol). Both fractions were saponified separately and the phytosterol content was
quantified by GC. The analytical method for the analysis of esterified and free sterols had a relative standard deviation
of 1.16% and an accuracy of 93.6–94.1%, which was comparable to the reference method for the total sterol analysis. A large
variation in the content and distribution of the sterol fraction between different vegetable oils can be observed. Corn and
rapeseed oils were very rich in phytosterols, which mainly occurred as steryl esters (56–60%), whereas the majority of the
other vegetable oils (soybean, sunflower, palm oil, etc.) contained a much lower esterified sterol content (25–40%). No difference
in the relative proportion of the individual sterols among crude and refined vegetable oils was observed. 相似文献
11.
ABSTRACTIn this work, diflubenzuron (DBZ) molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dynamic light scattering (DLS). The influences of synthetic conditions including template molecules, functional monomers and crosslinker on the surface morphology, particle size and size distribution of polymers were investigated. Scatchard analysis indicated the presence of specified recognition sites in MIPs. The Sips model was fitted better to the equilibrium data of MIPs over whole concentrations. The pseudo-second-order kinetic model was well fitted to the experimental data of adsorption kinetic experiment, suggesting the chemisorption mechanism between MIPs and DBZ. Four structurally similar compounds were used for the selectivity test of MIPs. It was observed that MIPs can selectively rebind the template molecules (DBZ) under the interference of four other structurally similar compounds. The application of MIPs in solid-phase extraction (SPE) offers a method for extraction and determination of benzoylureas (BUs) pesticides in apple samples prior to high-performance liquid chromatography (HPLC) analysis. 相似文献
12.
The gas-chromatographic determination of partial glycerides of sunflower (both high- and low-oleic acid varieties), peanut
and extra virgin olive oil was studied with a polar capillary column characterized by its high thermal stability. This column
allows for the determination of single diacylglycerols separated as a function of the position occupied by the individual
fatty acids on the glycerin backbone as well as by the degree of unsaturation of the fatty acids. 相似文献
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Vegetable oils are a renewable and an environmentally friendly alternative to petroleum-based oils in lubrication and other
important application areas. Vegetable oils fall into two broad chemical categories: triesters (or TG) and monoesters. Most
vegetable oils are triesters of glycerol with FA, whose characteristics are dependent on the chemistry and composition of
the FA residues. A small percentage of vegetable oils are monoesters of long-chain FA and fatty alcohols of varying chemistries.
In this work, the free energy of adsorption (ΔG
ads) of safflower (SA), high-oleic safflower (HOSA), and jojoba (JO), methyl oleate (MO), and methyl palmitate (MP) on steel
were investigated. SA and HOSA are TG of vegetable oils with FA residues of radically different degrees of unsaturation. JO
is a monoester vegetable oil. ΔG
ads is one of the major factors affecting the boundary friction properties of lubricant ingredients. ΔG
ads was found to increase in the order: HOSA≤SA<JO<MO≤MP. The results are consistent with the degree of functionality and other
chemical properties of the oils studied. 相似文献
15.
Manuela Buchgraber Franz Ulberth 《European Journal of Lipid Science and Technology》2002,104(12):792-799
The analytical performance of capillary gas‐liquid chromatographic (GLC) methods for the quantitative determination of trans fatty acids (TFA) in physically refined rapeseed and soybean oils was evaluated by 3 intercomparison studies. The participants were allowed to use their own methodology regarding derivatization and GLC conditions and were not requested to follow a fixed method protocol. However, certain requirements relating to the separation efficiency (chromatographic separation of critical pairs) and the accuracy (validation of the response factors using a certified reference material) of the method(s) applied, had to be fulfilled. All 12 participating laboratories employed fused silica capillary columns coated with cyanopropyl polysiloxane for the separation of fatty acid methyl esters. Analytical precision was sufficient (relative standard deviation for reproducibility 13%) for the quantification of trans isomers occurring at levels >0.1 g/100 g in physically refined vegetable oils, i.e. trans isomers of linolenic acid. For TFA levels <0.1 g/100 g (trans isomers of oleic and linoleic acid) precision dropped sharply (relative standard deviation for reproducibility >30%). 相似文献
16.
Determination of mixtures in vegetable oils and milk fat by analysis of sterol fraction by gas chromatography 总被引:1,自引:0,他引:1
L. Alonso J. Fontecha L. Lozada M. Juárez 《Journal of the American Oil Chemists' Society》1997,74(2):131-135
A rapid gas-chromatographic (GC) procedure was developed for the analysis of the total sterol fraction of vegetable oils,
milk fat or mixtures, to detect possible admixtures of sunflower with olive oil and the addition of vegetable oils to milk
fat. The method, which employs alkali-catalyzed transesterification with KOH/methanol, was compared with saponification procedures
with and without transformation of sterols into silyl derivatives prior to analysis. Repeatability of the method was assessed,
and the coefficient of variation was 6.0 and 8.0% for β-sitosterol in olive and sunflower oils, respectively. Recovery of
β-sitosterol ranged from 92.6 to 95.8 for both oils. The GC method assayed in this work requires little analysis time and
eliminates the need for saponification, extraction, and derivatization steps. It offers good repeatability and recovery and
is thus well suited to routine use. 相似文献
17.
Karen M. Bewig Andrew D. Clarke Craig Roberts Nan Unklesbay 《Journal of the American Oil Chemists' Society》1994,71(2):195-200
Discriminant analysis of four vegetable oil types (cotton-seed, peanut, soybean and canola) was performed by near-infrared
reflectance spectroscopy. The objective of this study was to provide an alternate method to differentiate vegetable oil types
and to classify unknown oil samples. Second derivative spectra of the vegetable oils were subjected to discriminate analysis
with Mahalanobis distances principles. A four-wavelength (1704, 1802, 1816 and 2110 nm) equation was derived, which produced
a sum of inverse squared distance of 0.0548. Although all four groups were successfully separated with a chi square of 18.9,
the soybean oil group is more dispersed in space than the other three groups. Iodine values of the soybean oil samples suggest
that this group may have a wide range of hydrogenation states. Discriminant analysis can be successfully used to differentiate
vegetable oil types and possibly could also be used to differentiate degree of hydrogenation and oxidative states of oils. 相似文献
18.
Brajendra K. Sharma Atanu Adhvaryu Zengshe Liu Sevim Z. Erhan 《Journal of the American Oil Chemists' Society》2006,83(2):129-136
Owing to the unfavorable impact on the environment of mineral oil-based lubricants, there has been a steady increase in the
demand for biodegradable, environment-friendly lubricants. However, development of a biodegradable base fluid that could replace
or partially substitute conventional mineral oil is a big challenge. Vegetable oils are recognized as rapidly biodegradable
and are thus promising candidates as base fluids in environment-friendly lubricants. Vegetble oils have excellent lubricity,
but poor oxidation and low-temeprature stability. This paper presents a series of structural modifications of vegetable oils
using anhydrides of different chain lengths. The reaction was monitored and products were confirmed by NMR, FTIR, gel permeation
chromatography, and thermogravimetric analysis (TGA). Experimental conditions were optimized for research quantity and for
laboratory scale-up (up to 4 lb=1.8 kg). The thermo-oxidation stability of these new lubricant base fluids was tested using
pressure differential scanning calorimetry and TGA. The chemically modified base fluids exhibit superior oxidation stability
in comparison with unmodified vegetable oils. These base fluids in combination with suitable additives exhibit equivalent
oxidation stability compared with mineral oil-based formulations. 相似文献
19.
A new process for the acyclic diene metathesis of vegetable oils utilizing Grubbs’ ruthenium catalyst (Cy3P)2Cl2Ru = CHPh has been developed. The higher molecular weight oligomers obtained can be separated from the unreacted oil and the
lower molecular weight alkene by-products easily. The reaction proceeds in the absence of solvent, with very low catalyst
concentrations (0.1 mole %) under moderate temperatures and low pressures. This process does not require the stringent exclusion
of water and oxygen that the previous method (Me4Sn plus WCl6) required. Low pressures appear to favor polymerization by removing the alkene by-products. The metathesis reaction has been
shown to be effective for many unsaturated vegetable oils, although some cases require oil pretreatment with silica gel. This
process is effective on a 2–200 g scale. Chromatographic separation and characterization of metathesized soybean oil indicate
that the process involves intermolecular and intramolecular carbon-carbon double-bond formation. 相似文献