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1.
The effects of oxygen pressure, substrate concentration and solvent on the rate and products of oxidation of methyl linoleate
were studied at 50 C with azobisisobutyronitrile as a radical initiator. The absolute and quantitative numbers for oxygen
uptake, substrate disappearance, and formation of conjugated diene and hydroperoxides were measured. Under the present conditions,
4 conjugated diene hydroperoxides, 13-hydroperoxy-9-cis, 11-trans-(2a), 13-hydroperoxy-9-trans, 11-trans-(3a), 9-hydroperoxy-10-trans, 12-cis-(4a), and 9-hydroperoxy-10-trans, 12-trans-(5a) octadecadienoic acid methyl esters, were formed almost quantitatively. The rate of oxidation decreased with decreasing oxygen
pressure. However, the ratio ofcis,trans totrans,trans hydroperoxides, (2a+4a)/(3a+5a), was independent of oxygen pressure, and this ratio increased with increasing methyl linoleate concentration, as found recently
by Porter. Further, the rate of oxidation and the ratio ofcis,trans/trans,trans hydroperoxides were dependent on solvent and increased with an increase in dielectric constant of solvent. A mechanism of
methyl linoleate oxidation consistent with these results is discussed.
Presented at the 15th Symposium on Oxidation Reactions, Nagoya, October 1981. 相似文献
2.
High-performance liquid chromatography and spectroscopic studies on fish oil oxidation products extracted from frozen atlantic mackerel 总被引:4,自引:0,他引:4
The formation of stable hydroxy derivatives from hydroperoxides produced during the oxidation of linoleic acid methyl ester
and fish oil were studied by reverse-phase high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry
(GC-MS) and 13C nuclear magnetic resonance (NMR) spectroscopy. The oxidation products identified were mixtures of four isomeric hydroxy
derivatives: 13-hydroxy-9-cis,11-trans-octadecadienoic, 13-hydroxy-9-trans,11-trans-octadecadienoic, 9-hydroxy-10-trans,12-cis-octadecadienoic, and 9-hydroxy-10-trans,12-trans-octadecadienoic acids. The presence of hydroxy compounds was confirmed by 13C NMR, which gave rise to a hydroxy carbon peak at 87 ppm, and by GC-MS, which showed three peaks corresponding to isomeric
mixtures of trimethylsilyl ethers of the oxidized linoleic acid methyl ester. The mass spectra scans of the three peaks showed
that they represent isomers of molecular weight 382 and are consistent with the molecular formula C22H42O3Si. In oil extracted from stored frozen mackerel, 13-hydroxy-9-cis,11-trans-octadecadienoic acid was more prominent compared to the model lipid systems. HPLC offered a sensitive means of detection
of hydroxy compounds produced both in the initiation and latter stages of oxidation. The effect of antioxidants added to the
fish mince prior to storage can also be monitored by HPLC. Thus, the monitoring of lipid oxidation hydroxy derivatives by
HPLC is of practical value in the efficient processing and quality control of fish, fish oils, and other fatty foodstuffs
in order to enhance the acceptability, nutritional, and safety aspects. 相似文献
3.
Sambasivarao Koritala 《Journal of the American Oil Chemists' Society》1972,49(9):534-536
Geometrical isomers of methyl linoleate were reacted with alakli, and the resulting conjugated isomers were separated intotrans,trans;cis,trans; andcis,cis fractions. The position of double bonds in the various fractions was determined by reductive ozonolysis.trans-9,trans-12-Isomer of linoleate formedtrans,trans- andcis,trans-conjugated dienes, whereascis-9,trans-12- andtrans-9,cis-12-isomers in addition formedcis,cis-conjugated dienes. The formation of the products is in accordance with the theoretical predictions. During conjugationtrans double bonds shifted to form atrans bond preferentially. During conjugation ofcis-9,trans-12- andtrans-9,cis-12-linoleate isomers, thecis double bond shifted preferentially over thetrans double bond. A small amount of diene not conjugated was probably a geometrical and positional isomer of the starting material. 相似文献
4.
Summary 1. Kinetic studies showed that concurrent oxidation of preformed hydroperoxides may be expected to take place at all stages
of the autoxidation of methyl linoleate. The rate of oxidation relative to the rate of autoxidation of unoxidized ester is
determined chiefly by the extent of the accumulation of hydroperoxides.
2. Infrared spectral analysis of hydroperoxides oxidized to various degrees indicated thattrans, trans diene conjugation and isolatedtrans double bonds produced in the autoxidation of methyl linoleate are related to the concurrent oxidation of the accumulated
hydroperoxides.
3. The low absorptivity observed for diene conjugation, compared to that which may be expected for the exclusive production
ofcis, trans diene conjugated hydroperoxide isomers during the autoxidation of methyl linoleate is attributed to the concurrent oxidation
of accumulated hydroperoxides.
4. The effect of antioxidants in giving a well-defined induction period in the oxidation of hydroperoxides isolated from autoxidized
methyl linoleate indicated that the oxidation proceeds by a chain reaction.
5. The primary reaction products of the oxidation of hydroperoxides isolated from autoxidized methyl linoleate were found
to be polymers formed in a sequence of reaction involving the diene conjugation.
6. Studies on the autoxidation of methylcis-9,trans-11-linoleate showed thatcis, trans isomerization of the conjugated diene took place with the concurrent production of isolatedtrans double bonds and loss of diene conjugation.
Hormel Institute publication no. 138. Presented before the American Oil Chemists’ Society, Philadelphia, Pa., Oct. 10–12,
1955.
This work was supported by a grant from the Hormel Foundation. 相似文献
5.
Carter Litchfield A. F. Isbell Raymond Reiser 《Journal of the American Oil Chemists' Society》1962,39(7):330-334
The four geometric isomers of methyl linoleate have been quantitatively determined by gas chromatography on Apiezon L and
DEGS polyester capillary columns. Three peaks were eluted from the Apiezon L column: (a) the 9-cis, 12-cis isomer; (b) the 9-cis, 12-trans isomer; and (c) the 9-trans, 12-cis and 9-trans, 12-trans isomers combined. The DEGS polyester column also resolved three peaks: (a) the 9-trans, 12-trans isomer; (b) the 9-cis, 12-cis and 9-cis, 12-trans isomers combined; and (c) the 9-trans, 12-cis isomer. Since the separation of isomers was different on each column, the content of each of the four isomers could be determined
from the combined results. Quantitative results agreed closely with the per centtrans bonds as determined by infrared analysis.
Presented at the fall meeting of the American Oil Chemists' Society, Chicago, Illinois, October 30-November 1, 1961.
Supported in part by a grant from Cargill, Ineorporated. 相似文献
6.
Sambasi Varao Koritala E. Selke H. J. Dutton 《Journal of the American Oil Chemists' Society》1973,50(8):310-316
Samples taken during deuteration of methyl linoleate with the title catalysts were separated into saturate, monoene and diene
fractions. Monoenes were further separated intocis andtrans fractions. A comparison of the double bond distribution in monoenes with those from hydrogenation of alkaliconjugated linoleate
indicated that up to 59% of the linoleate was reduced through a conjugated intermediate with nickel catalyst. The respective
percentages for palladium and platinum catalysts were 51 and 23. Copper catalysts have previously been shown to reduce linoleate
solely through conjugated intermediates. Copper-chromite catalyst showed infinite selectivity for the reduction of linoleate,
because stearate did not form. The decreasing order of various catalysts for the selective reduction was copper-chromite>>>Ni
at 195 C>Pd>Ni at 100 C>Pt. Computer simulation of platinum reduction indicated that ca. 20% of the linoleate was directly
reduced to stearate through a shunt. Geometrical isomers of linoleate were formed during reduction with all catalysts except
copper-chromite. Nickel catalyst formed bothtrans,trans- andcis,trans-isomers, as well as nonconjugatable dienes. These isomers were favored at the higher temperature and deuterium was incorporated
into them. Palladium and platinum did not isomerize linoleate to nonconjugatable dienes. Because conjugated dienes are more
reactive than linoleate, they were not found in appreciable amounts during reduction. Conjugated dienes were the only isomers
formed with copper-chromite catalyst. Deuterium was found in these conjugated dienes, which were also extensively isomerized.
As a result of isomerization and exchange during reduction of linoleate-as well as further exchange between deuterium and
monoenes-a wide distribution of isotopic isomers in monoenes was found with nickel, palladium and platinum catalysts. Since
isomerization of monoenes with copper-chromite is negligible, the isotopic distribution of monoenes must be due to exchange
of intermediate conjugated dienes followed by addition.
Presented at the AOCS Meeting, Ottawa, September 1972.
ARS, USDA. 相似文献
7.
The prooxidant property of inorganic chromium compounds was determined in methyl linoleate free from natural antioxidants
and metals. Prooxidant properties of inorganic chromium compounds appeared in order of sodium chromate > chromium (VI)-oxide
> chromium chloride > potassium chromate > chromium (III)-oxide > potassium dichomate. In comparison with the control, additions
of chromium compounds induced different amounts of autoxidation products derived from methyl linoleate, such as small amounts
of hydroperoxides and conjugated dienes and large amounts of hydroxy groups,α,β,γ,δ-unsaturated carbonyls, isolatedtrans double bonds, polymers, and free radicals. From these analytical data, the catalysis of chromium compounds in the autoxidation
of methyl linoleate seemed to be based on their abilities of abstracting a hydrogen from methyl linoleate and decomposing
hydroperoxides derived from the autoxidation of methyl linoleate. 相似文献
8.
N. A. Khan W. E. Tolberg D. H. Wheeler W. O. Lundberg 《Journal of the American Oil Chemists' Society》1954,31(11):460-466
- It has been confirmed that the principal products formed in the oxidation of methyl oleate by oxygen under a variety of conditions are predominantlytrans hydroperoxides. However no inversion of the double bond occurs in unoxidized oleate. Hence the conversion ofcis totrans double bonds and peroxide formation occur together in the same molecules.
- The autoxidation of methyl linoleate at low temperature yields predominantlycis,trans conjugated hydroperoxides. Autoxidation at 25°C., oxidation catalyzed by visible light, or ultraviolet light and copper soap catalyzed oxidation at temperatures appreciably above 0°C., lead to the formation primarily oftrans,trans conjugated hydroperoxides. The inversion of the second double bond in this case appears to be independent of the peroxide-forming reactions.
- The photochlorophyll oxidation of methyl linoleate leads to the formation of some unconjugated hydroperoxides, some of which containtrans double bonds.
- Under all of the conditions employed in the present investigation, the oxidation of methyl oleate and linoleate led primarily to the formation of monomeric peroxides which retained most of the unsaturation of the parent compound.
9.
S. Koritala 《Journal of the American Oil Chemists' Society》1980,57(9):293-298
The mechanism of hydrogenation at 900~950 psi with copper-chromite catalyst was investigated with pure methyl esters as well
as their mixtures. A comparison of double bond distribution intrans-monoenes formed during hydrogenation of linoleate and alkali-conjugated linoleate revealed that 85~95% of the double bonds
in linoleate conjugated prior to hydrogenation. The mode of hydrogen addition to conjugated triene and diene at high pressure
is similar to that at low pressure but positional and geometric isomerizations of unreduced conjugated esters were less at
high pressure. Geometric isomerization of methyl linoleate and linolenate was considerable at high pressure whereas it was
negligible at low pressure. The absence of conjugated products during hydrogenation of polyunsaturated fatty acid esters resulted
from their high reactivity. Conjugated dienes are 12 times more reactive than the triene, methyl linolenate, and 31 times
more reactive than the diene, methyl linoleate. The products of methyl linolenate hydrogenation were the same as those predicted
by the conjugation mechanism.
Presented at the 70th Annual Meeting of the American Oil Chemists' Society, San Francisco, April 29~May 3, 1979. 相似文献
10.
The mixture of diene hydroperoxides from methylene blue-sensitized oxidation of methyl linoleate was reduced with NaBH4 and the resulting alcohols were separated by high pressure liquid chromatography (HPLC). Four diene alcohols were isolated
in approximately equal yields from adsorption and reversed phase HPLC; the isomers were identified as methyl esters of 9-hydroxy-10,12-,
10-hydroxy-8,12-, 12-hydroxy-9,13- and 13-hydroxy-9,11-octadecadienoate. Formation of equal yields of both conjugated and
nonconjugated diene alcohols from methyl linoleate is characteristic of singlet oxygen oxidations. The detection of the easily
separated nonconjugated isomer methyl 10-hydroxy-trans-8,cis-12-octadecadienoate from methyl linoleate is proposed as a test to probe the involvement of singlet oxygen in biological
oxidations.
A preliminary report of these results was presented at the 177th meeting of the American Chemical Society, Honolulu, HI, April
1–6, 1979; see abstracts of papers, paper No. ORGN-375. 相似文献
11.
D. S. Raju M. R. Subbaram K. T. Achaya 《Journal of the American Oil Chemists' Society》1970,47(10):374-378
Potassium elaidate in slightly alkaline solution was hydrogenated for up to 7 hr with 1.5% of Rufert nickel catalyst at 150
C and 20 kg/sq cm pressure. Potassium linoleate was similarly hydrogenated with 1.0% catalyst for 7 hr, and the hydrogenation
continued for another 7 hr after addition of 0.5% fresh catalyst. Periodic samples from each were analyzed for component acids.
The positional isomers in thecis andtrans monoenes, isolated by preparative argentation thin layer (TLC) or column chromatography, were estimated after oxidation to
dicarboxylic acids. Some diene fractions were isolated for further examination. In potassium elaidate hydrogenation,cis monoenes were initially produced in considerable amounts, but to a lesser extent thereafter. Positional isomers were similarly
distributed in bothcis andtrans monoenes after prolonged hydrogenation. In the hydrogenation of potassium linoleate, a drop in iodine value (IV) of 60 units
occurred in the first hour, and 38% oftrans monoenes (in which the 10- and 11-monoenes constitute 32% each) were formed. The IV then fell only slowly, and up to 38%
ofcis monoene (mostly 9- and 12-isomers) was formed. Addition of fresh catalyst caused a major shift ofcis monoenes totrans forms. The diene fraction was mostly nonconjugated material with the first double bond at the 9, 8 and 10-positions. Minor
amounts of conjugated dienes were present as well as a dimeric product. 相似文献
12.
A simple method of preparation of methyl trans-10,cis-12- and cis-9,trans-11-octadecadienoates from methyl linoleate 总被引:2,自引:0,他引:2
O. Berdeaux L. Voinot E. Angioni P. Juanéda J. L. Sébédio 《Journal of the American Oil Chemists' Society》1998,75(12):1749-1755
Pure conjugated isomers of linoleic acid were prepared on a large scale by alkali-isomerization of purified methyl linoleate.
The methyl esters of alkali-isomerized linoleic acid contained mainly the methyl cis-9,trans-11- and trans-10,cis-12-octadecadienoates (44 and 47%, respectively). These two isomers were then separated and purified by a series of low-temperature
crystallizations from acetone. The isomeric purity obtained for the cis-9,trans-11-octadecadienoate isomer was >90% and that of the trans-10,cis-12-octadecadienoate isomer was 89 to 97%. The isolated yield of the two isomers corresponded to 18 and 25.7%, respectively,
of the starting material. The structure of the two isomers was confirmed using partial hydrazine reduction, silver nitrate-thin-layer
chromatography of the resulting monoenes and gas chromatography coupled with mass spectrometry of the 4,4-dimethyloxazoline
derivatives. Fourier transform infrared spectroscopy of the monoenes gave the confirmation of the geometry of each double
bond. 相似文献
13.
Taina I. Hmlinen Susanna Sundberg Marjukka Mkinen Seppo Kaltia Tapio Hase Anu Hopia 《European Journal of Lipid Science and Technology》2001,103(9):588-593
The aim of this study was to investigate whether hydroperoxides are formed in the autoxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and absence of α‐tocopherol. The existence of hydroperoxide protons was confirmed by D2O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH4. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The 13C and 1HNMR spectra of a mixture of 9‐hydroper‐oxy‐10‐trans,12‐cis‐octadecadienoic acid methyl ester (9‐OOH) and 13‐hydroperoxy‐9‐cis, 11‐trans‐octadecadienoic acid methyl ester (13‐OOH), which are formed during the autoxidation of methyl linoleate, were studied in detail to allow the comparison between the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides. The 13CNMR spectra of samples enriched with one of the two linoleate hydroperoxide isomers were assigned using 2D NMR techniques, namely Correlated Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gHMBC), and gradient Heteronuclear Single Quantum Correlation (gHSQC). The 13C and 1H NMR experiments performed in this study show that hydroperoxides are formed during the autoxidation of CLA methyl ester both in the presence and absence of α‐tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides. 相似文献
14.
The distribution of hydroperoxide isomers generated by photo-oxidation of natural lipids impregnated on the surface of dried
seaweed previously exposed to visible light and without added photosensitizer were studied. The surface of dried seaweed was
impregnated with linoleic acid methyl ester, and the sample was divided into two parts. One part was exposed to light from
a 100-W tungsten bulb (4500 lux) in a low-temperature room (5°C). The other part was kept in the dark as a control. Positional
isomers of the hydroperoxides generated from the impregnated linoleic acid methyl ester were separated individually by HPLC
and further identified by MS. The dried seaweed kept in the dark contained four hydroperoxide isomers, namely, 13-hydroperoxy-cis-9, trans-11-octadecadienoate, 13-hydroperoxy-trans-9, trans-11-octadecadienoate, 9-hydroperoxy-trans-10,cis-12-octadecadienoate, and 9-hydroperoxy-trans-10, trans-12-octadecadienoate. For the dried seaweed exposed to light, the oxidized lipids contained not only the same four isomers,
but also 12-hydroperoxy-cis-9, trans-13-octadecadienoate and 10-hydroperoxy-trans-8,cis-12-octadecadienoate. When fresh seaweed was dried in the sunlight, the formation of 12-cis,trans- and 10-cis,trans-hydroperoxides of naturally occurring methyl linoleate was verified. Dried seaweed was then impregnated with eicosapentaenoic
acid ethyl ester and exposed to light. Light exposure also generated certain hydroperoxide isomers attributable to singlet
oxygen oxidation, namely, 6-hydroperoxy-trans-4,cis-8, cis-11,cis-14,cis-17-ethyl and 17-hydroperoxy-cis-5,cis-8,cis-11, cis-14,trans-18-ethyl eicosapentaenoate. When dried sea-weed without any impregnated lipids was exposed to the light for 24 h in a cold
room (5°C), characteristic isomers, including both the 20-carbon FA isomers 6-OOH and 17-OOH as well as the 18-carbon FA isomers
10-OOH and 12-OOH, were detected in the light-exposed sample but were not found in the control. These results clearly show
that singlet oxygen oxidation of lipids occurred in the seaweed exposed to light. We concluded that this lipid oxidation was
catalyzed by chlorophyll as a photosensitizer in seaweed. 相似文献
15.
Two samples of soybean oil hydrogenated with copper-containing catalysts at 170 and 200 C were analyzed for their natural
and isomeric fatty acids. Methyl esters of the hydrogenated oils were separated into saturates, monoenes, dienes and trienes
by countercurrent distribution between acetonitrile and pentane-hexane. Monoenes were further separated intocis- andtrans-isomers on a silver-saturated resin column. Double bond location in these fractions was determined by a microozonolysis-pyrolysis
technique. The diene fraction was separated with an argentation countercurrent distribution method, and linoleate was identified
by infrared, ozonolysis and alkaliisomerization data. The double bonds in thecis-monoenes were located in the 9-position almost exclusively. However, the double bonds in thetrans-monoene were quite scattered with 10- and 11-isomers predominating. About 86% to 92% of the dienes consisted of linoleate
as measured by alkali isomerization. Other isomers identified as minor components includecis,trans andtrans, trans conjugated dienes and dienes whose double bonds are separated by more than one methylene group.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
16.
A mixture of all-trans-retinoic acid and iodine in heptane was irradiated. Two oxidation products were isolated by high performance liquid chromatography
and identified as all-trans- and 13-cis-4-oxoretinoic acid by nuclear magnetic reasonance, ultra violet, Infrared spectroscopy, and mass spectral analysis. Under
the same conditions, but without light, a mixture of all-trans- and 13-cis-retinoic acid resulted. The corresponding methyl esters were obtained when methyl all-trans-retinoate was used in place of all-trans-retinoic acid. 相似文献
17.
Richard O. Adlof 《Journal of the American Oil Chemists' Society》1999,76(3):301-304
Conjugated linoleic acid (CLA) has been associated with the reduction of chemically induced cancers in mice and rats and the
suppression of atherosclerosis in rats. We have found seed oils to be a valuable source of precursors for the rapid preparation
of gram quantities of deuterium-labeled fats. Methyl santalbate (methyl 11-trans-octadecen-9-ynoate), obtained from Santalum album (Linn.) seed, was reduced with Lindlar catalyst, quinoline, and deuterium gas to produce, in yields of 65–75%, the gram quantities
of methyl 9-cis,11-trans-octadecadienoate-9,10-d2 (CLA-d2) we required for metabolism and oxidation studies. Unlike monoacetylenic and methylene-interrupted polyacetylenic fatty acid
methyl esters, the conjugated system was reduced with no noticeable break in the rate of deuterium uptake. The quantity of
poison (quinoline) present did influence the amount of CLA-d2 produced, but the production of overreduced fatty acid methyl esters (perhaps because of the conjugated system) could not
be prevented. Fractionation of the reaction mixture by silver resin chromatography resulted in the isolation of >99% chemically
pure CLA-d2 in yields of 60–70%. 相似文献
18.
A high-performance liquid chromatographic method, using post-column detection with diphenyl-1-pyrenyl-phosphine (DPPP), was
developed for the quantitative and qualitative determination of isomeric lipid hydroperoxides (OOH). The OOH eluted from a
normal-phase column were passed through a photodiode array detector and then mixed with DPPP solution in a reaction coil heated
at 80°C. DPPP oxide formed by the reaction with OOH was determined by monitoring the fluorescence intensity at 380 nm and
excitation at 352 nm. The conjugated diene OOH (13-cis, trans- and 9-cis, trans-OOH) and nonconjugated OOH (12-cis-trans- and 10-cis, trans-OOH) from photosensitized oxidation of methyl linoleate were determined in a molar ratio of 31∶29∶19∶21, respectively. However,
only the two conjugated hydroperoxides were detected by ultraviolet absorption at 234 nm. Further applications were carried
out for the determination of OOH of methyl oleate and methyl linolenate. This method proved to be useful for the determination
of the OOH containing both conjugated and nonconjugated diene structures. 相似文献
19.
J. A. Fioriti A. P. Bentz R. J. Sims 《Journal of the American Oil Chemists' Society》1966,43(8):487-490
A colorimetric method, based upon the reaction of the oxirane group with picric acid, was used to determine the epoxide content
of heated vegetable oils. The picration method is particularly suitable for measuring small quantities of epoxide because
it is much more sensitive than the common titrimetric methods, and it is not subject to interference from cyclopropene, conjugated
dieneols, or α, β-unsaturated carbonyls.
Thin-layer chromatography was used to separate mixtures of picrated, epoxidized methyl esters. Separation ofcis- andtrans-methyl epoxystearate, methyl epoxyoleate, and methyl diepoxystearate in a mixture of these four esters was achieved in this
manner. The presence of saturatedcis- andtrans-epoxystearates and unsaturated epoxides was demonstrated in heated vegetable oils.
Presented, in part, at the AOCS Meeting in Cincinnati, October 1965. 相似文献
20.
A previous study of autoxidation products by high pressure liquid chromatography (HPLC) of methyl oleate and linoleate was
extended to methyl linolenate. Autoxidized methyl linolenate was fractionated by HPLC either after reduction to allylic alcohols
on a reverse phase system, or directly on a micro silica column. Isolated oxidation products were characterized by thin layer
and gas liquid chromatography and by ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Secondary products
from the autoxidation mixtures (containing 3.5–8.5% monohydroperoxides) included epoxy unsaturated compounds (0.2–0.3%), hydroxy
or hydroperoxy-cyclic peroxides (3.8–7.7%), epoxy-hydroxy dienes (<0.1%), dihydroxy or dihydroperoxides with conjugated diene-triene
and conjugated triene systems (0.9–2.9%). Cyclization of the 12- and 13-hydroperoxides of linolenate would account for their
lower relative concentration than the 9- and 16-hydroperoxides. Dihydroperoxides may be derived from the 9- and 16-linolenate
hydroperoxides. Cyclic peroxides and dihydroperoxides are suggested as important flavor precursors in oxidized fats. 相似文献