共查询到20条相似文献,搜索用时 15 毫秒
1.
A. G. Gopala Krishna J. V. Prabhakar 《Journal of the American Oil Chemists' Society》1994,71(11):1245-1249
The components responsible for increased stability of raw peanut oil at a high relative humidity (RH) of 91% were examined
in peanut oil and methyl linoleate systems. Of the constituents, the native gums, which were mostly phospholipids and glycolipids,
showed increased antioxidant activity at 91% RH. The isolated components of the gums, namely phospholipids and glycolipids,
were prooxidant individually or in combination. Tocopherols did not show increased antioxidant activity at 91% RH. 相似文献
2.
Yasushi Endo Riichiro Usuki Takashi Kaneda 《Journal of the American Oil Chemists' Society》1985,62(9):1387-1390
To understand the mechanism of the antioxidant effect of chlorophyll on the autoxidation of oils in the dark, antioxidant
activities of several derivatives of chlorophyll were compared. Antioxidant activities were observed in chlorophyll derivatives
such as protopor-phyrin methyl ester and its magnesium chelated compound. Porphyrin seems to be an essential chemical structure
for the antioxidant activity of chlorophyll. Chlorophyll did not decompose the hydroperoxides, but reduced free radicals such
as 1,1-diphenyl-2-picrylhydrazyl. Electron spin resonance spectrum of the π-cation radical was recorded during the oxidation
of chlorophyll in methyl linoleate solution. These observations suggest that chlorophyll may act as a hydrogen donor to break
the chain reaction. 相似文献
3.
Nobuji Nakatani Yukari Tachibana Hiroe Kikuzaki 《Journal of the American Oil Chemists' Society》2001,78(1):19-23
A model substrate oil using methyl linoleate was established for the determination of the antioxidant activity by Oil Stability
Index (OSI) method. OSI values for methyl linoleate with different concentrations (5–100%) in silicone oil were measured at
different temperatures (70–120°C). As the temperature increased, the OSI value decreased in each concentration of methyl linoleate.
Optimal temperature and concentration of antioxidants, α-tocopherol, and butylated hydroxytoluene on OSI values for 10% methyl
linoleate model oil was measured at 90, 100, 110, and 120°C. The logarithmic relationship between temperature and OSI using
model substrate oil was similar to that of soybean oil. Furthermore, application of some spice extracts to this model oil
system was carried out to give results thhat compared well with those available in the literature. Thus, the procedure using
methyl linoleate-silicone oil as a model substrate oil is available for evaluating the antioxidant activity by the OSI method. 相似文献
4.
Hong-Sik Hwang Jill K. Winkler-Moser Sean X. Liu 《Journal of the American Oil Chemists' Society》2022,99(5):407-419
Previous studies reported that several amino acids had strong antioxidant activity in vegetable oils under frying conditions. In this study, amino acids were converted to their sodium or potassium salts, and a heating study was conducted with 5.5 mM amino acid salts in soybean oil (SBO) at 180°C. Sodium salts of amino acids including alanine, phenylalanine, and proline and disodium glutamate had significantly stronger antioxidant activity than the corresponding amino acids, and potassium salts had stronger antioxidant activity than sodium salts. Potassium salts of alanine and phenylalanine more effectively retained tocopherols in SBO than the corresponding amino acids during heating. Phenylalanine potassium salt had stronger antioxidant activity than phenylalanine in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Phenylalanine potassium salt at 5.5 mM more effectively prevented oil oxidation than tert-butyl hydroquinone, a synthetic antioxidant, at its legal concentration limit (0.02%) indicating its feasibility as a new antioxidant for frying. 相似文献
5.
The antioxidant effects of ion exchange resins and ethyleneimine polymer on the autoxidation products of methyl linoleate
in a heterogeneous reaction system are discussed. Results from analyses of the various autoxidation products from linoleate
samples with and without the antioxidants showed that the addi-tion of the antioxidants did not change the original autoxidation
mechanism of methyl linoleate. How-ever, the antioxidants did retard the autoxidation in response to their antioxidant activity
and, compared with a linoleate control, changed the yields of some autoxidized products such as an increased amount of conjugated
diene hydroperoxides in linoleate samples with added ion exchange resins. 相似文献
6.
The effect of new antioxidants, such as phenothiazine derivatives, on the autoxidation of methyl linoleate was evaluated by
estimating the induction period using the weighing method. Peroxide values (iodometry and IR), refractive indices, mol wts,
and UV and IR spectra were measured to investigate the extent of the autoxidation. The induction period evaluated from the
weighing method gives almost the same value as that from the peroxide values. It was shown that some new phenothiazine derivatives
are remarkably effective antioxidants, and, besides, the mechanism for the autoxidation of methyl linoleate containing phenothiazine
derivatives as antioxidants is probably of the same type as that for the substrate alone. This study also investigated the
reaction mechanism of phenothiazine derivative antioxidants by determining the electron spin resonance spectra for the antioxidants
in the autoxidation of methyl linoleate. Then, the following mechanism was proposed. That is, within the induction period,
these inhibitors hold stable nitroxide radicals (>NO*) in the reaction between the antioxidant amino radical (>N*), produced
by the reaction of the antioxidant with ROO* or O2, and the peroxy radical (ROO*). Besides, the more superior the phenothiazine derivative antioxidant, the more inactive the
antioxidant makes oxygen and the peroxy radical for the methyl linoleate autoxidation and also for the antioxidant oxidation.
Presented at the 12th World Congress of ISF, Milan, 1974. 相似文献
7.
Free radical reactions of peroxidizing lipids with amino acids and proteins: An ESR study 总被引:4,自引:0,他引:4
Free radical transfer from oxidizing methyl linoleate to amino acids and proteins was studied in dry model systems incubated
for periods up to 20 days. Electron spin resonance was used to study free radical production. Free radicals were detectable
in the amino acids lysine, arginine, histidine, tryptophan, and cysteine. Reduced glutathione and, to a limited extent, cystine
also gave free radical signals. Free radicals produced in proteins primarily showed central singlet lines, attributable to
carbon-centered radicals, with g=2.004±0.001. Sulfhydryl proteins also exhibited downfield shoulders at g≄2.015 and 2.023
that were essentially identical to peaks observed in cysteine and reduced glutathione. The field positions of sulfur resonance
in cysteine and proteins suggested a sulfur-oxygen complex rather than thiyl radicals.
This report is part of ScD Thesis, MIT, 1974 (KMS). 相似文献
8.
M. J. Taylor T. Richardson R. D. Jasensky 《Journal of the American Oil Chemists' Society》1981,58(5):622-626
Various amino acids, selected for their potential antioxidant activity, were, covalently attached to 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic
acid (Trolox-C), a lower homolog of vitamin E that has great antioxidant effectiveness. The resulting Troloxylamino acids
(T-AA) had greater antioxidant effectiveness than Trolox-C in a linoleate emulsion system oxidized by hemoglobin. Troloxyl-tryptophan-methyl
ester and Troloxyl-methionine-methyl ester were the most effective T-AA evaluated in the linoleate emulsion. However, butylated
hydroxyanisole (BHA), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and α-tocopherol were more antioxidant
than any T-AA in the emulsion system. In a Schaal oven test at 45 C. Trolox-C was by by far the most effective antioxidant
evaluated in corn oil. BHT and Troloxylcysteine had significant antioxidant activity in corn oil, but no other T-AA was antioxidant
in corn oil. In butter oil, Trolox-C again had the highest antioxidant activity, and BHA and BHT were also highly antioxidant.
All t-AA had antioxidant activity in butter oil, with Troloxyl-methioninc and Troloxyl-cysteine having the grcatest antioxidant
effectiveness. The T-AA of highest antioxidant activity were hydrolyzed by chymotrypsin and/or trypsin, in vitro. 相似文献
9.
Methyl linoleate, emulsified in borate buffer with sodium lauryl sulfate, was used to study the pro- or antioxidant effect
of 0-phosphocholine, 0-phosphoethanolamine, 0-phosphoserine, as well as the corresponding nonphosphoryl compounds. Oxygen
uptake was calculated from rate data obtained at 37 C with an oxygen electrode. The results were similar for the corresponding
phosphoryl and nonphosphoryl bases. 0-Phosphocholine and choline had little effect at either pH 7.9 or 10.2. 0-Phosphoethanolamine
and ethanolamine significantly increased oxygen uptake at pH 7.9, but significantly decreased uptake at pH 10.2. 0-Phosphoserine
and serine decreased oxygen uptake at both pH values. The catalytic activities of the bases investigated may be attributed
to their functional groups. The phosphoryl and β-hydroxy groups exhibited no catalytic activity in the autoxidation of methyl
linoleate emulsions at either pH 7.9 or 10.2. The α-carboxyl amino group of 0-phosphoserine and serine decelerated autoxidation
at both pH values. The amino group H3N+ of the primary amine accelerated autoxidation, but the H2N: group and the reverse effect. Since the quaternary amino group (CH3)3N+ did not affect autoxidation at either pH 7.9 or 10.2, we concluded that the presence of the N−H bond may be necessary for
the prooxidant activity of an amine, and that the presence of a pair of free electrons on the nitrogen of an amine is necessary
for its antioxidant activity. Kinetically, the autoxidation of methyl linoleate emulsion without added base was in agreement
with Farmer’s proposed mechanism involving a bimolecular dissociation of hydroperoxides. However, methyl linoleate emulsion
at pH 7.9 and 37 C in the presence of ethanolamine or 0-phosphoethanolamine was autoxidized by a mechanism involving a combined
mono- and bimolecular dissociation of hydroperoxides.
Submitted as partial requirement for a Ph.D. degree in Agricultural Chemistry. Presented in part at the AOCS Meeting, San
Francisco, April 1969. 相似文献
10.
The antioxidant activities of the flavonol aglycones, quercetin and myricetin, and their selected glycosides were compared
in bulk methyl linoleate oxidized at 40°C. Methyl linoleate hydroperoxide formation, hydroperoxide isomer distribution, and
ketodiene formation were followed by using high-performance liquid chromatography (HPLC) analysis. The aglycones, quercetin
and myricetin, were consistently more active in bulk methyl linoleate than their glycosides and more active than α-tocopherol
at 500 and 1000 μM. At 50 μM, the order of activity was myricetin > α-tocopherol > quercetin, and the order of activity of
quercetin and its derivatives was quercetin > quercitrin > isoquercitrin > rutin. Myricitrin was slightly less active than
myricetin. The sugar moiety was shown to have a marked effect on the antioxidant activity of flavonols. The rhamnoside derivatives,
quercitrin and myricitrin, both possessed activity close to that of their corresponding aglycones. The different activities
of glycosides could be partly explained by different solubilities and by differences in oxidizability of glycosides containing
a monosaccharide or disaccharide at the C3 position. The effect on hydroperoxide isomer distribution indicates that α-tocopherol was a more effective hydrogen donor
than flavonoids, although flavonoids were more effective in inhibiting oxidation of methyl linoleate. 相似文献
11.
The rates of autoxidation of oleic acid, ethyl oleate, linoleic acid, 10,12-linoleic acid, ethyl linoleate, trilinolein, pentaerythritol linoleate, dipentaerythritol linoleate, elaidolinolenic acid, linolenic acid, ethyl linolenate, trilinolenin, and methyl arachidonate have been studied by oxygen uptake in a Warburg respirometer and the results are compared with the rates of enzymatic oxidation of lipoxidase substrates. The increase in the number of double bonds in a fatty acid by one increases the rate of oxidation of the fatty acid or its esters by at least a factor or two. Earlier findings that acids oxidize more rapidly than their esters have been confirmed. The initial rates of lipoxidase oxidation of ethyl linoleate, ethyl linolenate, and methyl arachidonate were found to be essentially the same. 相似文献
12.
Summary Alkali-isomerized linoleic acid and its methyl ester have been found to have boiling points higher than the corresponding
normal C18 acids and esters.
By careful fractional distillation of methyl esters of alkali-isomerized C18 cottonseed acids, methyl linoleate of 95% or more purity is obtained consisting of 75% conjugated methyl linoleate and some
20% of methyl ester of an altered linoleic acid.
Paper No. 69, Journal Series, Research Department, General Mills, Inc. (Presented at the 19th Annual Fall Meeting of the American
Oil Chemists’ Society, Nov. 7–9, 1945, in Chicago, Ill.) 相似文献
13.
A comparison between the determination of the peroxide value by the methods of Wheeler and Sully (iodometric titration) and
that of Stine, et al. (ferric thiocyanate method) was made. Some oxidized vegetable oils, H2O2, t-butyl hydroperoxide, cumene hydroperoxide, methyl oleate hydroperoxides, and methyl linoleate hydroperoxides were used
as substrates. One-hundred percent of the methyl linoleate hydroperoxides were recovered by the Wheeler reduction, 85% by
the Sully method. The Wheeler method was used to reduce the methyl linoleate hydroperoxides to the corresponding hydroxy acids.
In the Sully procedure, the hydroxy acids are only intermediates which are dehydrated to octadecatrienoic acids. One equivalent
methyl linoleate hydroperoxide oxidized two equivalents of I− (Wheeler) and four equivalents of Fe2+ (Stine, et al.). By way of contrast, H2O2 needs only two equivalents I− or Fe2+ for reduction. The excess consumption of reduction equivalents in the ferric thiocyanate method probably is caused by secondary
reactions of the methyl linoleate hydroperoxide acyl residue. 相似文献
14.
Antioxidant activities of selected oriental herb extracts 总被引:9,自引:0,他引:9
S. Y. Kim J. H. Kim S. K. Kim M. J. Oh M. Y. Jung 《Journal of the American Oil Chemists' Society》1994,71(6):633-640
Antioxidant activities of methanol extracts of 180 Oriental herbs were studied by determining the peroxide values of linoleic
acid during storage at 50°C. Among the herb extracts tested, 44 species showed strong antioxidant activities on the oxidation
of linoleic acid. The antioxidative effects of these 44 selected herb extracts were studied further in a methyl linoleate
system during storage for 35 d. Among the 44 species tested, 11 species had particularly high antioxidative effects. The effects
of type of extraction solvent (methanol, petroleum ether and ethyl acetate) on the antioxidant activities of the 11 species
were studied. Antioxidant activities of most herb extracts were greatly dependent on the extraction solvent used; however,
some of the extracts showed strong antioxidant activities regardless of the solvents used for the extraction. Among the 11
herbs selected, based on the antioxidant activity of their methanol extracts, two (i.e.,Psoralea corylifolia L. andSorphora angustifolia Sieb. & Zucc.) were selected for further study in lard held at 75°C for 7 d. The methanol extracts ofP. corylifolia L. andS. angustifolia Sieb. & Zucc. greatly decreased the peroxide formation of lard during storage. Treatment with 0.20% methanolic extract ofP. corylifolia L. exhibited significantly stronger antioxidant effect on the oxidation of lard than treatment with 0.02% butylated hydroxyanisole
(P<0.05). 相似文献
15.
The antioxidant activity of ion exchange resins and ethyleneimine polymer was determined in methyl linoleate free from natural
antioxidants and metals. Superior antioxidant activities were recognized in an ion exchange resin with NH groups and in the
ethyleneimine polymer. The antioxidant activities in these heterogeneous reaction systems increased in linear proportion to
the amount present. These antioxidant activities in the heterogeneous reaction system were mainly owing to their ability to
donate hydrogen to the peroxy radicals produced in the autoxidation of methyl linoleate. The antioxidant radicals produced
in these cases were very stable and generally couldn’t participate in the increase of the induction periods in the autoxidation
of methyl linoleate by terminating the peroxy radicals. These results have never been obtained in the homogeneous reaction
system but are characteristic in the heterogeneous one. 相似文献
16.
Bottino NR 《Lipids》1967,2(2):155-160
Rats fed a fat-free diet from weaning were contined on that diet alone or supplemented with methyl linoleate, methyl linoleate
plus a mixture of antibiotics, or methyl arachidonate.
Dietary linoleate and arachidonate reduced the concentration of octadecenoic acid and increased that of stearic acid in the
mucosa and luminal lipids. This effect was prevented in the mucosa but not in the intestinal contents by antibiotic supplementation
of the linoleate diet.
Evidence for the conversion of linoleic into eicosatetraenoic acid was found in both mucosa and luminal lipids. The conversion
was impaired by the addition of antibiotics to the diet.
Linoleate feeding combined with antibiotic addition provided evidence for the intestinal hydrogenation of dietary linoleic
into either octadecenoic or stearic acids by separate routes, the latter being impaired by antibiotic ingestion.
The ingestion of methyl linoleate or arachidonate modified only slightly the fecal fatty acid pattern of rats previously on
a fat-free diet. 相似文献
17.
Heidi H. Y. Cheung Ming Chee Yeung Yong Jie Li Berto P. Lee 《Aerosol science and technology》2013,47(8):643-654
The hygroscopic tandem differential mobility analyzer (HTDMA) has been frequently used to measure the hygroscopic properties of atmospheric aerosols at a fixed high relative humidity (RH) of about 90%. To evaluate if such measurements could be used to determine the hygroscopicity of aerosols at lower RH, simultaneous hygroscopic growth factor (GF) and size-resolved composition measurements were made with an HTDMA and a high-resolution aerosol mass spectrometer (HR-AMS), respectively, at a coastal site in Hong Kong from January to June and in August 2012. A total of 58 cycles of dehydration (decreasing RH) and hydration (increasing RH) of 100 nm and 200 nm particles with organic-to-inorganic mass ratio ranging from 0.19 to 1.97 were measured at RH = 10–93%. The Kappa (κ) equation developed by Petters and Kreidenweis in the year 2007 was used to determine (i) κ at individual RHs (κRH) and (ii) best-fit κ covering the range of RHs measured (κf) for the more-hygroscopic (MH) mode, which describes more than 80% of the particles in each cycle, during dehydration. Overall, κ at 90% RH or above (κ>90) fell between 0.18 and 0.48, and was within 15% of κf in 83% of the datasets. Regression analysis between κ>90 or κf and AMS mass fractions showed that κ was positively correlated with sulfate but negatively correlated with organic and nitrate. In most cases, κRH increased as RH decreased and the average increase in κ was 45% from 90% RH to 40% RH, but these differences yielded insignificant changes in the GF-RH curves. The Zdanovskii-Stokes-Robinson (ZSR) estimated κ were mostly within 20% of κ>90 and κf. GF predictions using the empirical correlation of κ with AMS mass fractions or the ZSR estimated κ were within 10% of additional measurements and hence κ>90 is useful for predicting GF at lower RHs.Copyright 2015 American Association for Aerosol Research 相似文献
18.
C. D. Evans D. G. McConnell E. N. Frankel J. C. Cowan 《Journal of the American Oil Chemists' Society》1965,42(9):764-770
A chromatographic study was carried out to investigate the nature of polymeric products in edible oils. Dimers from low-temp
oxidation of methyl linoleate were compared with thermal dimers from high-temp polymerization of conjugated methyl linoleate.
The distilled dimers were subjected to liquid-partition chromatographic separations on silicic acid columns as methyl esters,
as free acids, and as methyl esters prepared by saponification and reesterification. Chromatographically isolated dimer fractions
were also rechromatographed before and after each treatment.
When thermal dimer esters are saponified and reesterified, chromatographic recoveries are quantitative, and the expected changes
in polarity result; whereas, with oxidative dimer esters, gross changes in polarity occur. Chromatographic separations of
dimer esters or their acids fractionate into distinct areas of increasing polarity.
Presented at the AOCS Meeting, New Orleans, 1964. Honorable Mention, Bond Award Competition.
A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, USDA. 相似文献
19.
E. N. Frankel C. D. Evans D. G. Mcconnell E. P. Jones 《Journal of the American Oil Chemists' Society》1961,38(3):134-137
A liquid partition chromatographic method was developed to isolated and determine hydroperoxides in autoxidized fatty acids
or their methyl esters. By the use of benzene containing 2 to 4% methanol as the mobile solvent, the hydroperoxides were separated
from unoxidized fatty acids or methyl esters and from secondary and polymeric decomposition products. In the analyses of oxidized
fatty acids, diethyl ether was necessary to elute the secondary decomposition products.
Saponification of autoxidized fatty esters destroyed the peroxides as determined iodometrically, but the resulting acids contained
a fraction which was eluted in the same position as hydroperoxide acids. Evidence showed that this fraction is a monomeric
hydroxy fatty acid containing conjugated cis-traux and trans-trans unsaturation.
Fatty ester hydroperoxides were isolated chromatographically in yields and purity comparable to those reported in the literature
by countercurrent distribution. The concentrations of methyl linoleate hydroperoxide determined chromatographically were smaller
than indicated by the peroxide value and diene conjugation of the autoxidized methyl linoleate.
This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department
of Agriculture. 相似文献
20.
The hydrolytic degradation of polycarbonate resins is a first-order process in terms of the decrease in average molecular weights under a relative humidity (RH) and temperature. Two analysis procedures have been developed for making life-cycle predictions of polycarbonate at any combination of humidity and temperature. The first prediction procedure uses an Arrhenius equation derived for determination of the activation energy of polycarbonate hydrolysis tested at various temperatures under a constant RH. The rate constants at any combination of temperature and RH can be determined for a new resin tested at three or more RHs under a temperature, since the logarithm of the Arrhenius intercept has a linear empirical relationship with RH. The second prediction procedure uses a linear relationship between the logarithm of the rate constant and RH derived from the humid-aging of polycarbonate tested at various RHs under a constant temperature. The rate constants at any combination of temperature and RH can be determined for a new resin tested at three or more temperatures under a RH, since the intercept of the above linear relationship has another linear empirical relationship with temperature. 相似文献