Differences in Oxidation Kinetics Between Conjugated and Non‐Conjugated Methyl Linoleate

Luna, Pilar; Fuente, Miguel Ángel de la; Salvador, D.; Márquez‐Ruiz, Gloria

doi:10.1007/s11745-007-3113-x

Cited by 36 publications

(40 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Empirical kinetic reassessment of the early data by Brimberg & Kamal-Eldin (2003) suggests that oligomers having an average of three monomers would be kinetically favoured at the beginning of the oxidation and that the extent of oligomerization increases with increased temperature. Recently, Luna et al (2007) confirmed the formation of polymeric products during autoxidation of Me 9c,11t-CLA and Me 10t,12c-CLA. In their study, oxidized monomers, dimers and polymers were quantified concomitantly by high-performance size-exclusion chromatography (HPSEC).…”

Section: Polymerization (Pathway A)mentioning

confidence: 83%

“…Therefore, the identification of the primary autoxidation products is of crucial importance for deeper understanding of the autoxidation of CLA. In particular, the mechanism(s) of formation and the structures of the oligomeric products, which are the main products of CLA autoxidation (Kern et al 1955(Kern et al , 1956Privett 1959;Luna et al 2007), remain more or less speculative, without a clear knowledge of the primary species involved in their initiation.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanisms for the formation of the oligomers and the identified secondary products remain more or less a matter of speculation, due to the lack of knowledge of the early autoxidation steps and of the preceding autoxidation products. Furthermore, analyses of oligomeric product mixtures can be anticipated to be challenging due to heterogeneity of the oligomers (Muizebelt & Nielen 1996;Luna et al 2007) and therefore characterization of the primary products may prove helpful in elucidation not only of the formation mechanisms of the oligomers but also of their structures. Moreover, if sufficient quantities of pure primary products could be produced, their further reactions may be investigated and their biological activity evaluated in a quantitative manner.…”

Section: T H E R E F O R E K N O W L E D G E O F C L a O X I D A T mentioning

confidence: 99%

“…It is well established by PV and oxygen consumption measurements (Allen et al 1949), by MS (Muizebelt et al 2000), and by HPSEC (Luna et al 2007) that the autoxidation profile of CLA differs from that of its nonconjugated counterpart. Peroxide products accumulate more slowly and only in small amounts compared to linoleic acid (Allen et al 1949;Suzuki et al 2004).…”

Section: Figure 11mentioning

confidence: 99%

“…Peroxide products accumulate more slowly and only in small amounts compared to linoleic acid (Allen et al 1949;Suzuki et al 2004). CLA absorb less oxygen per mole of oxidized substrate than linoleic acid (Allen et al 1949;Tsuzuki et al 2004) and produces mainly polymeric products (Luna et al 2007). Because of these differences between the autoxidation of conjugated and nonconjugated diene fatty acids, the result should be interpreted with care.…”

Section: Figure 11mentioning

confidence: 99%

See 4 more Smart Citations

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Pajunen

Johansson

Hase

et al. 2008

Lipids

View full text Add to dashboard Cite

The autoxidation of conjugated linoleic acid (CLA) is poorly understood in spite of increasing interest in the beneficial biological properties of CLA and growing consumption of CLA-rich foods. In this thesis, the autoxidation reactions of the two major CLA isomers, 9-cis,11-transoctadecadienoic acid and 10-trans,12-cis-octadecadienoic acid, are investigated. The results contribute to an understanding of the early stages of the autoxidation of CLA methyl ester, and provide for the first time a means of producing and separating intact CLA methyl ester hydroperoxides as well as basic knowledge on lipid hydroperoxides and their hydroxy derivatives.Conjugated diene allylic monohydroperoxides were discovered as primary autoxidation products formed during autoxidation of CLA methyl esters in the presence and absence oftocopherol. This established that one of the autoxidation pathways of CLA methyl ester is the hydroperoxide pathway.Hydroperoxides were produced from the two major CLA methyl esters by taking advantage of the effect of -tocopherol to promote hydroperoxide formation. The hydroperoxides were analysed and separated first as methyl hydroxyoctadecadienoates and then as intact hydroperoxides by HPLC. The isolated products were characterized by UV, GC-MS, and NMR techniques. In the presence of a high amount of -tocopherol, the autoxidation of CLA methyl ester yields six kinetically-controlled conjugated diene monohydroperoxides and is diastereoselective in favour of one particular geometric isomer as a pair of enantiomers. The primary autoxidation products produced from the two major CLA isomers include new positional isomers of conjugated diene monohydroperoxides, the 8-, 10-, 12-, and 14-hydroperoxyoctadecadienoates. Furthermore, two of these new positional isomers have an unusual structure for a cis,trans lipid hydroperoxide where the allylic methine carbon is adjacent to the cis instead of the usual trans double bond.The 1 H and 13 C NMR spectra of nine isomeric methyl hydroxyoctadecadienoates and of ten isomeric methyl hydroperoxyoctadecadienoates including the unusual cis,trans hydroperoxides, i.e. Me 8-OOH-9c,11t and Me 14-OOH-10t,12c, were fully assigned with the aid of 2D NMR spectroscopy. The assigned NMR data enabled determination of the effects of the hydroxyl and hydroperoxyl groups on the carbon chemical shifts of CLA isomers, identification of diagnostic signals, and determination of chemical shift differences of the olefinic resonances that may help with the assignment of structure to as yet unknown lipid hydroperoxides either as hydroxy derivatives or as intact hydroperoxides.A mechanism for the hydroperoxide pathway of CLA autoxidation in the presence of a high amount of -tocopherol was proposed based on the characterized primary products, their relative distribution, and theoretical calculations. This is an important step forward in CLA research, where exact mechanisms for the autoxidation of CLA have not been presented before. Knowledge of these hydroperoxide formation steps is of cr...

show abstract

Section: Polymerization (Pathway A)mentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: T H E R E F O R E K N O W L E D G E O F C L a O X I D A T mentioning

confidence: 99%

Section: Figure 11mentioning

confidence: 99%

Section: Figure 11mentioning

confidence: 99%

See 3 more Smart Citations

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Pajunen

Johansson

Hase

et al. 2008

Lipids

View full text Add to dashboard Cite

show abstract

Microencapsulation of Conjugated Linoleic Acid (CLA)‐Rich Oil with Skimmed Milk Components Protects against Polymerization

Holgado

García-Martínez

Velasco

et al. 2018

J Americ Oil Chem Soc

View full text Add to dashboard Cite

Oils rich in conjugated linoleic acid (CLA) are currently used in functional foods because of the positive health effects of some CLA isomers. In this work, microencapsulation of a CLA-rich oil (containing approx. 80% of a mixture of 9c, 11 t, and 10 t, 12c-linoleic acid) with skimmed milk components is proposed as a means to protect it from oxidation and polymerization. The main physicochemical characteristics, i.e. glass transition temperature, mean oil globule size, and distribution, were evaluated. Microencapsulated samples, both intact and devoid of free oil fraction, along with the bulk oil, were oxidized at 30 C in the dark for 3 months. Throughout storage, free and encapsulated oil fractions were separately extracted from samples and analyses including substrate loss by Gas liquid chromatography-Flame ionization detection, polymer determination by High performance size exclusion chromatography-Refractive index detection, and tocopherol content determination by High performance liquid chromatography-Fluorescence detection were performed. Results showed that free oil oxidized much more rapidly than encapsulated oil. High amounts of polymers accumulated in samples with considerable high levels of tocopherols remain in encapsulated oil fractions. In samples devoid of free oil, a drastic change in the physical properties occurred but the oil polymerized to a similar extent to that found in the encapsulated fractions of intact samples.

show abstract

Effects of tocopherols and tocotrienols on the inhibition of autoxidation of conjugated linoleic acid

Kim

et al. 2010

Euro J Lipid Sci & Tech

View full text Add to dashboard Cite

The effect of eight vitamin E homologues, i.e. a-, b-, g-, and d-tocopherol and a-, b-, g, and d-tocotrienol, on the inhibition of autoxidation of conjugated linoleic acid (CLA) were investigated.The oxidation was carried out in the dark for 21 days at 50 8C and monitored by peroxide values (PV) and TBA values. The levels of the individual vitamin E homologues in CLA during storage were determined by HPLC. g-Tocopherol exhibited the highest antioxidant activity among the homologues tested in this study when the antioxidant activities of the individual homologues in CLA were compared by PV. The order of antioxidant activity of eight homologues was g-tocopherolThe degradation rates of a-tocopherol and a-tocotrienol were faster than those of the other homologues, whereas d-tocopherol had the highest stability in CLA during storage. All homologues exhibited an antioxidant activity by inhibiting the formation of secondary oxidation products. It appears that a-tocotrienol and b-tocotrienol have significantly higher antioxidant activities for secondary oxidation in CLA than a-tocopherol and b-tocopherol. Meanwhile, the other homologues, namely g-tocopherol, g-tocotrienol, d-tocopherol, and d-tocotrienol, exhibited similar antioxidant activity for secondary oxidation in CLA.

show abstract

Differences in Oxidation Kinetics Between Conjugated and Non‐Conjugated Methyl Linoleate

Cited by 36 publications

References 26 publications

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Microencapsulation of Conjugated Linoleic Acid (CLA)‐Rich Oil with Skimmed Milk Components Protects against Polymerization

Effects of tocopherols and tocotrienols on the inhibition of autoxidation of conjugated linoleic acid

Contact Info

Product

Resources

About