共查询到20条相似文献,搜索用时 31 毫秒
1.
Yasushi Endo Hiromi Endo Kenshiro Fujimoto Takashi Kaneda 《Journal of the American Oil Chemists' Society》1991,68(10):769-771
Edible refined, bleached and deodorized (RBD) soybean oil was fractionated by silicic acid column chromatography to identify
minor components responsible for flavor reversion. Minor components from oil eluted with diethyl ether/n-hexane (1:1) were
compared with those from corn and canola oils. All vegetable oils contain free fatty acids, diglycerides and sterols as major
ingredients in this fraction. However, unusual triglycerides consisting of 10-oxo-8-octadecenoic acid and 10-and 9-hydroxy
octadecanoic acids were detected in RBD and crude soybean oils. 相似文献
2.
杜氏盐藻通过水热液化制备得到的生物油,先采用溶剂分割分别得到正己烷相、二氯甲烷相和乙醚相,再对二氯甲烷相进行柱层析分离纯化。正己烷相和乙醚相直接通过GC-MS和FT-IR进行分析,二氯甲烷相先经柱层析分离后结合GC-MS、二次质谱和FT-IR等确认不同馏分的产物组成。研究结果表明:二氯甲烷相经柱层析分离可得到16个馏分,分别是石油醚馏分(A1),主要是烯烃类;石油醚:乙酸乙酯馏分(A2),主要是酸类化合物;石油醚:丙酮馏分(A3),主要是酰胺类;石油醚:甲醇馏分(A4),主要是烷烃类;甲醇馏分(A5),主要是十八碳烯酰胺。经柱层析分离纯化后,生物油的回收率高达91.38%;获取较全的生物油组分信息,为藻类液化机理的分析和生物油的改质提供了依据。 相似文献
3.
The level of petroleum ether insoluble oxidized fatty acids in used frying fats is one of the recommended criteria for assessing
their quality in Germany; however, the method of determination is time consuming and inaccurate. Gel permeation chromatography
(GPC) allows the determination of dimeric and oligomeric triglycerides in a heated fat irrespective of the presence of oxidized
material. An indication of the total amount of polar and oxidized compounds can be obtained by liquid chromatography (LC)
on a silica gel column in connection with a moving-wire detector. A comparatively simple and quick method is the separation
of polar and unpolar components in a used frying fat by means of column chromatography (CC) on silica gel. Over a large number
of investigations, a good correlation was seen between the results obtained with GPC, LC, and CC and the amount of petroleum
ether insoluble oxidized fatty acids isolated from used frying fats. Limits of the analytical data obtained by the new methods
are proposed which indicate deterioration of used frying fats. 相似文献
4.
With the standardized method for polar compound determination in frying fats, the cyclic monomers were found in the apolar fraction as well in the polar one. Moreover some compounds are not eluted from the column; the amount of these non-eluted products increases with the oil degradation state. These observations raise some questions about the nutritional experiments carried out with this type of fractionation. 相似文献
5.
Erhard Schulte 《European Journal of Lipid Science and Technology》2004,106(11):772-776
The polar components, formed in fats during deep‐frying, comprise a multitude of different artifacts. Their content is a suited indicator of fat quality. As an alternative to the time‐ and chemicals‐consuming official methods a simplified micromethod is described. The method employs general laboratory equipment and disposable consumables. The eluent mixture of petroleum ether + diethyl ether (90 + 10) was substituted by a mixture of isohexane + diisopropyl ether (85 + 15), because the high volatility of the former eluent caused problems at elevated ambient temperatures, e.g. during hot summers. 相似文献
6.
Enzymatic hydrolysis of the acylglycerol products obtained from thermally oxidized vegetable oils was studied. Corn, sunflower
and soybean oils were heated in the laboratory at 180 C for 50, 70 and 100 hr with aeration and directly fractionated by silicic
acid column chromatography. By successive elution with 20%, then 60% isopropyl ether inn-hexane, and diethyl ether, the thermally oxidized oils were separated into three fractions: the nonpolar fraction (monomeric
compounds), slightly polar fraction (dimeric compounds), and polar fraction comprising oligomeric compounds. Enzymatic hydrolysis
with pancreatic lipase showed that the monomers were hydrolyzed as rapidly as the corresponding unheated oils, the dimers
much more slowly, and the oligomeric compounds barely at all. Overall, the hydrolysis of the dimers was less than 23% of that
for the monomers, with small differences among the oils. Longer heating periods resulted in greater reductions in hydrolysis
of the dimeric compounds. These results suggest that the degree of enzymatic hydrolysis of the fractionated acylglycerol compounds
is related to differences in the thermal oxidative deterioration, and amounts of polar compounds in the products. 相似文献
7.
K. Aitzetmüller 《European Journal of Lipid Science and Technology》1973,75(4):256-260
The analysis of frying fats by low-pressure liquid chromatography (LC) using a Pye LC detector is described. With silicagel columns, chromatograms are obtained which show the extent of oxidative decomposition of the fat by the appearance of polar products eluted after the triglyceride peak. If a steep ethanol front is programmed after the appearance of the ?non-polar triglyceride”? peak, the ?total more polar products”? may be eluted as one peak and compared against ?total dimeric triglycerides”? as obtained from gel permeation work. Chromatograms of various frying oils show the accumulation of polar products with time. 相似文献
8.
Dimitra P. Houhoula Vassiliki Oreopoulou Constantina Tzia 《European Journal of Lipid Science and Technology》2004,106(11):746-751
The effect of oregano on the oxidative stability of cottonseed oil during frying of potato chips and on the storage stability of the products was studied. The ground spice or an ethanol‐derived extract was added to the oil before frying. The results showed that both additives decreased the rates of accumulation of conjugated dienes, polar compounds, polymerized triacylglycerols, dimeric triacylglycerols and the p‐anisidine value of the frying oil, while the hydrolytic compounds were not affected. The major decrease was observed in the accumulation of polymerized and dimeric triacylglycerols. The storage stability of the produced chips was estimated by the rate of increase of the peroxide value and of the conjugated dienes in the oil absorbed by them. Both rates were depressed when oregano was added to the frying oil, with the protective action of oregano extract being considerably greater than that of ground oregano. The protective action of oregano extracts obtained by successive extractions with petroleum ether (PE), diethyl ether (EE) and ethanol (EtOH) and added to the chips after frying was also examined. The results showed that the EE and EtOH extracts were very effective against oxidative deterioration. 相似文献
9.
Rapid separation of neutral lipids,free fatty acids and polar lipids using prepacked silica sep-Pak columns 总被引:6,自引:10,他引:6
A method is described for the separation of neutral lipid, free fatty acid and polar lipid classes using small (600 mg), prepacked
silica Sep-Pak columns. Combinations of hexane and methyltertiarybutylether were used to progressively elute cholesteryl ester
first then triglyceride from the column. After column acidification, fatty acids were eluted followed by cholesterol. Recoveries
of these lipids were 96% or greater. Polar lipids were eluted from the column using combinations of methyltertiarybutylether,
methanol and ammonium acetate. Phospholipid classes could not be separated completely from each other. Phosphatidylethanolamine
and phosphatidylinositol eluted together, whereas the more polar phosphatidylcholine, sphingomyelin and lysophosphatidylcholine
were eluted as a second fraction. Recoveries of each phospholipid was greater than 98%. 相似文献
10.
In preliminary experiments, soybean oil was heated at 275 C for 12 hr in the presence of N2 or air. Feeding studies with rats showed that the oil heated in the presence of air, oxidatively polymerized oil, retarded
weight gain more than that heated with N2, thermally polymerized oil. Oxidatively polymerized oil was fractionated with silicic acid column chromatography, and the
fraction eluted with ether (fraction III) proved to be most toxic to mice. For chemical studies combined with bioassays, additional
oxidatively polymerized oil was prepared by aeration at 185 C for 90 hr, and the product was fractionated by silicic acid
column chromatography. The material originally eluted with ether (fraction III) was eluted in stages, and fraction IIIc proved
to be most toxic in a mouse bioassay. IR, UV and NMR analyses did not indicate the presence of C−O−O−C or C−O−C linkages or
aldehyde groups or aromatic compounds. Fraction IIIc was converted to its methyl esters and molecularly distilled to yield
two fractions: one containing unpolymerized fatty acid esters and one giving evidence of more functional groups per molecule
and of dimeric material. This “dimeric” fraction was more toxic to mice. IR analysis of this fraction revealed carbonyl groups,
and NMR showed several functional groups on alkyl chains. Treatment with sodium borohydride and with hydroiodic acid revealed
no C−O−O−C and no C−O−C linkages. Mass spectrography showed peaks at mass 586 and 293; in the reduced fraction a peak also
occurred at mass 143, suggestive of cleavage of some of the chains. It is tentatively concluded that a highly toxic material
formed in oil heated in air is a dimer of triglyceride molecules.
One of seven papers presented in the symposium “Biological Significance of Autoxidized and Polymerized Oils,” JOCS-AOCS Joint
Meeting, Los Angeles, April 1972. 相似文献
11.
We investigated the role that cuticular hydrocarbons (CHC) play in sexual communication by the mustard leaf beetle, Phaedon cochleariae (Coleoptera: Chrysomelidae). In laboratory bioassays, male P. cochleariae attempted to copulate with living or freeze-killed females as often as with males. However, the duration of copulation with
females was longer than with males. To elucidate the impact of CHC on this behavior, cuticular compounds of adults of both
sexes were extracted with dichloromethane. Male mating attempts with glass beads treated with the dichloromethane extract
were nearly as frequent as with living beetles. The dichloromethane extract was fractionated by silica gel chromatography,
and the biological activity of the fractions was tested by applying them to glass beads. A non-polar hexane fraction significantly
elicited mating behavior, whereas the polar methanol fraction did not, likely because it contained defensive compounds from
exocrine glands located in the elytra and pronota. Interestingly, a mixture of both the non-polar and polar fraction tended
to elicit more mating attempts than did the non-polar hexane fraction alone. Further fractionation of the significantly active
hexane fraction by silver nitrate column chromatography revealed that saturated CHC elicited mating behavior, but the olefins
did not. GC-MS analyses of dichloromethane cuticular extracts showed that the male and female CHC profiles were qualitatively
identical, but differed in their relative composition. Canonical discriminant analysis showed that CHC profiles of males and
females formed separate clusters. Nevertheless, the results of our bioassays demonstrated that male and female CHC did not
elicit sex discriminative male behavior, but induced mating by males regardless of the sex of the partner. 相似文献
12.
Basavalingappa Rekha Belur Rangaswamy Lokesh Ambale Gundappa Gopala Krishna 《Journal of the American Oil Chemists' Society》2014,91(10):1665-1676
Compared to other vegetable oils, rice bran oil (RBO) has a characteristic dark color which further deepens upon heating or frying of foods in the oil. Darkening of the oil during heating has been studied. The dark color‐causing material in crude, chemically refined and physically refined rice bran oils was separated using a silica gel column for a hexane‐eluted oil fraction and a methanol eluted fraction. The methanol eluted fraction for all the above three types of RBO produced a dark color upon heating, hence the physically refined RBO methanol fraction was investigated further and contained monoglycerides (23.4 %) and diglycerides (67.4 %) of linoleic + linolenic acids in its methanol fraction as analyzed by column chromatography and HPLC which decreased in concentration after heating. The linoleic acid level of 37.7 % in the methanol fraction was reduced significantly to 18 % after heating (52.3 % reduction). The IR and NMR spectra were similar to those of a monoglyceride/diglyceride with NMR spectra indicating a lower amount of olefinic protons for the heated sample. These results showed that the darkening of RBO was due to the oxidation and polymerization of monoglycerides/diglycerides containing linoleic acid/linolenic acid. 相似文献
13.
Ch Gertz 《European Journal of Lipid Science and Technology》1986,88(12):475-480
Chromatographic Methods in the Investigations of Deep-Frying Fats 125 samples of deep-frying fats were investigated by various chromatographic methods (gaschromatography, gel permeation chromatography, column chromatography). The results were compared with the known criteria of alteration products (petroleum ether oxidised fatty acids (OXF). A content of 0.7% corresponded to 24.7% polar materials. The fraction of monomer glycerides was determined by gel permeation chromatography (GPC) on polystyrol-divinyl-copolymer (PL-Gel) which can be used at high pressure. However, gel permeation chromatography determines the sizes of the molecules and does not distinguish between non-oxidised and oxidised monomer glycerides in frying fats. Therefore the application of gaschromatography and GPC is proposed to calculate the part of non-oxidised monomer tri- and diglycerides. It was found that fat-samples with more than 0.7% oxidised fatty acids contained less than 86.7% monomer non-oxidised and oxidised di- and triglycerides and less than 71.6% monomer unaltered di- and triglycerides. 相似文献
14.
Eleni P. Kalogianni Calliope Karastogiannidou Thodoris D. Karapantsios 《Journal of the American Oil Chemists' Society》2009,86(6):561-571
The effect of repeated deep frying of potatoes versus repeated heating/quenching on the chemical profile of palm oil was investigated.
The novelty of the work is that the frying and heating/quenching experiments were conducted under similar time-temperature
profiles. The effects of the frying load (potato-to-oil ratio: 1/7 and 1/35 kgpotatoes/loil) and of the time-temperature profile were examined. Whole palm oil and its polar fraction were analyzed using high pressure
size exclusion chromatography. Both repeated frying and repeated heating/quenching generated polar and polymerization products
in palm oil. Interestingly, no hydrolysis or other decomposition products were generated under any of the examined conditions.
The presence of potatoes during frying in palm oil increased the concentration of polymerization products and polar compounds
compared to oils without potatoes significantly. The effects of frying load on oil quality depended on frying time. No significant
effect of frying load was observed up to frying times of 13 h (or 10 frying batches). However, frying oil quality was affected
by frying load once frying times exceeded 24 h (or 20 batches). 相似文献
15.
Triolein was heated under simulated deep-fat frying conditions at 185 C for 74 hr. The thermally oxidized triolein was converted into methyl esters and then fractionated by urea exclusion. The urea adduct-forming ester (89.2%) was found to be methyl oleate unchanged by the frying treatment. The nonurea adduct-forming esters (10.8%) were further fractionated by silicic acid column chromatography into nine fractions with molecular weights ranging from 304 to 742. Physical and chemical analyses of the fractions indicated that some of them contained oxygen atoms which could not be accounted for by ordinary functional group analyses. The polymers isolated were formed by both carbon-to-carbon and carbon-to-oxygen linkages. The nonpolar dimers were further purified by thin layer and gas chromatography. Structure elucidation revealed that they consisted of a noncyclic dimer and a noncyclic dimer containing a carbonyl group, each of which amounted to 1.36% of the triolein originally used. The polar polymers were studied by depolymerization and the analysis of the depolymerized products. It was estimated that the triolein used for simulated deep fat frying contained 1.1% trimers formed through carbon-to-carbon linkages, 1.9% dimers and trimers joined through carbon-to-carbon linkages, and 3.1% dimers and trimers joined through carbon-to-oxygen or carbon-to-carbon linkages in the same molecule and also dimers and trimers in which all the monomeric units were joined through carbon-to-oxygen linkages. The precise form of the oxygen linkages are not known. However, the fact that it is not cleavaged by HC1 and HI suggests ether linkages. 相似文献
16.
Thermal Decomposition of Partially Hydrogenated Rapeseed Oil During Repeated Frying Traditional and Fast French Fries
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Dominik Kmiecik Joanna Kobus‐Cisowska Bartosz Kulczyński 《Journal of the American Oil Chemists' Society》2018,95(4):473-483
The aim of this study was to compare thermal degradation of oil, especially the composition of the polymer in a polar and nonpolar fraction of oil, used for repeated frying of fast and traditional French fries. The French fries were fried using the partially hydrogenated rapeseed oil. Fast French fries were characterized by a half shorter frying time compared to traditional ones. The frying process was done at 170 °C ± 5 °C in 5‐l electric fryers and carried out in 15‐min cycles for 48 hours. The content of thermal decomposition of triacylglycerol (TAG) in both fractions of oil was analyzed by high‐performance size‐exclusion chromatography (HPSEC). In all analyzed samples, thermal decomposition products were found. However, the composition of a polar and nonpolar fraction of oil was not the same. In a nonpolar fraction, only the monomers and hydrolysis products of TAG were observed. In a polar fraction, dimers, trimers, and oligomers of TAG were also found. The shorter time of frying the fast French fries resulted in a lower total and individual polymers content in all steps of analysis compared to the oil used for frying the traditional French fries. 相似文献
17.
Thermoxidative and hydrolytic changes in sunflower oil used in fryings with a fast turnover of fresh oil 总被引:1,自引:0,他引:1
C. Cuesta F. J. Sánchez-Muniz C. Garrido-Polonio S. López-Varela R. Arroyo 《Journal of the American Oil Chemists' Society》1993,70(11):1069-1073
The modification of a sunflower oil used for 75 repeated deep-fat fryings of potatoes, with a fast turnover of fresh oil during
frying, was evaluated by measuring the total polar components isolated by column chromatography. The total polar components
increased rapidly during the first 20 fryings from 5.09±0.21 (mean±SD) mg/100 mg unused oil to 15.99±0.40, followed by minor
but also significant changes until the thirtieth frying (17.99±0.41 mg/100 mg oil). The level did not increase further with
continued frying. Further, the polar fraction was examined by high-performance size-exclusion chromatography. Triglyceride
polymers increased from 0.10±0.01 mg/100 mg unused oil to 1.65±0.13 and 3.44±0.17 mg/100 mg oil at the twentieth and seventy-fifth
fryings, respectively. Triglyceride dimers also increased significantly from 0.75±0.12 mg/100 mg unused oil to 6.25±0.28 (mg/100
mg oil) at the twentieth frying and to 7.09±0.31 mg/100 mg oil at the thirtieth frying, with no further significant changes.
Oxidized triglycerides also significantly increased, but at the twentieth frying reached a near-steady state of 6.26 mg/100
mg oil. Diglycerides and free fatty acid levels, related to hydrolytic alteration, did not increase with continued fryings.
The results indicate that during deep-fat frying of potatoes with fast turnover of fresh sunflower oil, more thermoxidative
than hydrolytic processes take place. A dramatic leap of total polar content and a change of compounds related to thermoxidative
alteration of the oil were found during the first twenty fryings, followed by minor changes and by a tendency to reach a near-steady
state throughout the successive fryings. 相似文献
18.
Alkaline contaminant materials are formed in frying oils during cooking. The ACM can be eluted from the same International
Union of Pure and Applied Chemists-Association of Official Analytical Chemists (IUPACAOAC) silica gel column used to determine
polar materials in frying oils. The ACM are eluted with methanol after “non-polar” and “polar” fractions already have been
eluted from the column. A residue of silica gel in the methanol eluate must be insolubilized before the ACM can be identified
and quantitated. IR was used to identify sodium oleate as the major constituent of ACM from a set of restaurant generated
frying oil samples. 相似文献
19.
J. D. Caldwell B. S. Cooke M. K. Greer 《Journal of the American Oil Chemists' Society》2011,88(11):1669-1674
Analysis of used frying oil samples by high performance liquid chromatography–size exclusion chromatography (HPLC–SEC or HPSEC)
was compared to AOCS Official Method Cd 20-91 (silica gel column chromatography) for the purpose of developing a rapid analysis
of total polar compounds (TPC). In a direct comparison of the two analytical methods using four different sets of used frying
oils (21 total oil samples) ranging from fresh to discard quality (4.3 to 35.4% TPC by column chromatography), the weight
percent total polar compounds (%TPC) determined by HPLC–SEC averaged 0.71% higher than the values by silica gel column chromatography.
Reproducibility of the HPLC–SEC method of s
r = 0.30 and RSDr% = 1.22 compares to the variability of s
r = 0.29 and RSDr = 1.3 for samples of approximately the same %TPC, reported in AOCS Method Cd 20-91. Because the rapid method does not separate
pure (non-polar) triacylglycerol (TAG) and polar, oxidized TAG (OX-TAG), a high concentration of OX-TAG will quantitatively
affect the results. This places practical limits on the types of studies to which the method may be applied if a separate
analysis for the OX-TAG is not performed. Advantages of the HPLC–SEC method include the following. It uses about 75% less
solvent than standard column chromatography methods for determination of %TPC. This HPLC–SEC method is very similar to AOCS
Official Method Cd 22-91, and thus, also separates and quantifies polymerized triacylglycerols. The HPLC–SEC method determines
both TAG polymer concentration and %TPC of used frying oils in about 1 h. 相似文献
20.
Kenji Okumura Kazunori Hayashi Itsuro Morishima Kichiro Murase Hideo Matsui Yukio Toki Takayuki Ito 《Lipids》1998,33(5):529-532
Ceramides and 1,2-diacylglycerol have been demonstrated in intracellular signaling pathways. A method of simultaneous mass
determination of ceramides and 1,2-diacylglycerol in tissues was developed using the latroscan which combines thin layer chromatography
and flame ionization detection (TLC/FID) techniques. Because of relatively low amounts of these components in tissues, the
fraction of nonpolar lipids, which included ceramides and glycerides, was eluted with chloroform/acetone mixture (3∶1, vol/vol)
through a silicic acid column to eliminate the polar phospholipids. Development of Chromarods was carried out using three
solvent systems in a four-step development technique. The relationship of the peak area ratio to weight ratio compared with
cholesteryl acetate added as an internal standard was linear. The amount of ceramides increased with incubation of rat heart
homogenate and human erythrocyte membranes in the presence of sphingomyelinase (E.C. 3.1.4.12). The latroscan TLC/FID system
provided a quick and reliable assessment of ceramides and 1,2-diacylglycerol. 相似文献