On the kinetics of the autoxidation of fats: substrates with conjugated double bonds

Brimberg, Ulla I.; Kamal‐Eldin, Afaf

doi:10.1002/ejlt.200390000

Cited by 37 publications

(36 citation statements)

References 21 publications

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“…Because the formation of such products has a high energy barrier, the 1,2-and 1,4-addition reactions of oxygen are not plausible pathways for the formation of cyclic peroxides. Formation of these peroxides through splitting of oligomers as suggested by Brimberg & Kamal-Eldin (2003) seems more probable but remains to be confirmed. It could, for example, be envisioned that decomposition of a dimeric alkoxyl radical, formed by the unzipping of a trimeric addition product, might yield a bisepoxide and the subsequent rearrangement of this epoxide a 1,2-dioxine (Fig.…”

Section: Figure 21mentioning

confidence: 93%

“…The data supports oxygen-carbon rather than carbon-carbon polymerization, and indicates that appreciable amounts of isolated transunsaturation resides in the polymer fraction. 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.…”

Section: Polymerization (Pathway A)mentioning

confidence: 99%

“…These mechanisms seem, however, highly unlikely because the direct addition of triplet oxygen to the double bonds of CLA violates the Wigner's spinconservation rule. Brimberg and Kamal-Eldin (2003) have proposed, based on kinetic data, that monomeric products are formed through splitting of the oligomers. This mechanism seems plausible but remains to be confirmed.…”

Section: Figure 11mentioning

confidence: 99%

“…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. The addition mechanism would produce trimers with peroxide crosslinks (see examples in Fig.…”

Section: Figure 19mentioning

confidence: 99%

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

Pajunen

Johansson

Hase

et al. 2008

Lipids

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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...

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Section: Figure 21mentioning

confidence: 93%

Section: Polymerization (Pathway A)mentioning

confidence: 99%

Section: Figure 11mentioning

confidence: 99%

Section: Figure 19mentioning

confidence: 99%

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

Pajunen

Johansson

Hase

et al. 2008

Lipids

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“…Initially, the production of hydroperoxides is dormant and becomes noticeable at induction period (l, 21 days with released tocopherol of 241 mmol/kg), after which their concentration increases rapidly with time ( Figure 3). This phenomenon is typical of lipid oxidation in oil-rich food with or without antioxidants (Brimberg & Kamal-Eldin, 2003;Zhu, Schaich, Chen, Chung, & Yam, 2012). The induction period or time for conjugated dines or hydroperoxides to arrive at certain low level is usually adopted as a shelf life.…”

Section: Resultsmentioning

confidence: 99%

Effect of tocopherol loading and diffusivity on effectiveness of antioxidant packaging

Lee

Yam

2013

CyTA - Journal of Food

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Controlled-release of antioxidant from packaging film to the oil-rich food can help retard the oxidation of lipids. The production of hydroperoxides in the oil-rich liquid food, an index of oxidation, was modeled from the literature data and simulated mathematically as function of tocopherol loading and diffusivity in the packaging film in order to find the best package design parameters that can provide the extended shelf life. Fick's second law combined with the oxidation kinetics was solved numerically to determine the shelf life, which is the time for hydroperoxides to reach 41.25 mmol/kg in the food. For a typical system consisting of packaging film of 76.2 mm thickness in contact with the food of 50 times larger in volume at 408C, the optimal loading that led to the longest shelf life was found to be lower with higher diffusivity film.Keywords: oxidation; induction period; hydroperoxides; controlled release; pro-oxidation La liberacio´n controlada de un antioxidante desde la pelı´cula de empaquetado al alimento envasado puede ayudar a retrasar la oxidacio´n de los lı´pidos. En la generacio´n de hidropero´xidos en los alimentos oleosos se modelo´y simulo´matema´ticamente el ı´ndice de oxidacio´n en funcio´n de la concentracio´n y la difusividad del tocoferol en la pelı´cula del envase para determinar los mejores para´metros de disen˜o de empaquetado que permitan prolongar la vida de anaquel. La ecuacio´n de la velocidad de oxidacio´n y de la segunda ley de Fick se combinaron y se resolvieron nume´ricamente para cada tipo de envase con el fin de determinar la vida de anaquel, el tiempo que requieren los hidropero´xidos para alcanzar una concentracio´n de 41,25 mmol/kg en el alimento. Para un sistema tı´pico consistente en una pelı´cula de envase con un espesor de 76,2 mm en contacto con un alimento cuyo volumen es cincuenta veces mayor a una temperatura de 408C, la concentracio´n ó ptima que proporciono´una vida de anaquel ma´s prolongada fue menor con una pelı´cula de difusividad ma´s alta.

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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

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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.

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On the kinetics of the autoxidation of fats: substrates with conjugated double bonds

Cited by 37 publications

References 21 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

Effect of tocopherol loading and diffusivity on effectiveness of antioxidant packaging

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

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