Effects of α‐, γ‐, and δ‐Tocopherols on Oxidative Stability of Soybean Oil

Jung, Mun Yhung; Min, David B.

doi:10.1111/j.1365-2621.1990.tb03960.x

Cited by 160 publications

(67 citation statements)

References 10 publications

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“…The inhibitory activity oftocopherol (and other tocopherols) against lipid oxidation is associated with an optimal concentration of the antioxidant, after which stabilization decreases . The optimum concentration of -tocopherol, for example, for inhibiting the formation of hydroperoxides in the oxidation of purified soybean oil at 55 °C was 100 ppm (Jung & Min 1990). …”

Section: Figure 12mentioning

confidence: 99%

“…Several studies suggest that tocopherols at higher than the optimal concentration accelerate the formation of hydroperoxides, especially at the early stage of oxidation (Peers & Coxon 1983;Jung & Min 1990;Yanishlieva & Marinova 1992;Bowry & Stocker 1993;Huang et al 1995;Bowry & Ingold 1999). This effect has been described as a pro-oxidant effect but is better described as loss of antioxidant efficacy at post-optimal concentrations, because it is plausible that not only the concentration of -tocopherol but also of several other chemical species that may participate in the initiation of the oxidation process are above a certain optimal concentration (Fuster et al 1998;Evans JC et al 2002;Kamal-Eldin et al 2008).…”

Section: Figure 12mentioning

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 12mentioning

confidence: 99%

Section: Figure 12mentioning

confidence: 99%

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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“…Not only carotenoids, but also other antioxidants are beneficial in terms of improving oxidative stability only up to a point, with the increased loading of antioxidants determining a pro-oxidant effect (Moure et al, 2001). For example, in a study on the effects of tocopherols on the oxidative stability of soybean oil, Jung and Min, (1990) reported that concentrations of tocopherols higher than what was determined as optimum resulted in pro-oxidant effects.…”

Section: Oxidative Stabilitymentioning

confidence: 99%

Effect of carotenoids, extracted from dry tomato waste, on the stability and characteristics of various vegetable oils

et al. 2018

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SUMMARY:In this study, various vegetable oils were enriched with carotenoids originating from dry tomato waste using ultrasound-assisted extraction, microwave-assisted extraction and maceration. Analyses of total carotenoids, color and oxidative stability (determined by free radical scavenger activity, peroxide value, Rancimat method and DSC analysis) were carried out. Commercial oils without enrichment were used for comparison. The results showed that the carotenoid contents of the oils increased significantly by increasing incorporation of dry tomato waste. Also, maceration proved to extract significantly higher amounts of these compounds. In some oils the extraction of dry tomato waste improved their oxidative and thermal stability while in others it caused an increase in the peroxide value and a decrease in induction time. Finally, the color parameters of the oils were significantly influenced. Enriched oils could be a potential source of bioactive compounds and might have significant antioxidant activity when ingested as part of a dietary regime. KEYWORDS:Carotenoids; Color; Extraction; Oxidative Stability; Tomato waste; Vegetable oils RESUMEN: Efecto de los carotenoides, extraídos de residuos de tomates secos, sobre la estabilidad y caracterís-ticas de aceites vegetales. En este estudio varios aceites vegetales se enriquecieron con carotenoides obtenidos a partir de residuos de tomates secos utilizando extracción asistida por ultrasonido, extracción asistida por microondas y maceración. Se llevó a cabo un análisis de los carotenoides totales, el color y la estabilidad oxidativa (determinada por la actividad captadora de radicales libres, el índice de peróxidos, el método Rancimat y el análisis DSC). Los aceites comerciales sin enriquecimiento se usaron como testigos. Los resultados mostraron que el contenido de carotenoides de los aceites aumentó significativamente al aumentar la incorporación de residuos secos de tomate. Además, la maceración demostró extraer cantidades significativamente más altas de estos compuestos. En algunos aceites, el residuo seco de tomates mejoró su estabilidad oxidativa y térmica, mientras que en otros causó un aumento en el índice de peróxido y una disminución en el tiempo de inducción. Finalmente, los parámetros de color de los aceites se vieron significativamente influenciados. Los aceites enriquecidos podrían ser una fuente potencial de compuestos bioactivos y podrían tener una actividad antioxidante significativa cuando se ingieren como parte de un régimen dietético.

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“…Due to the high tocopherol content of crude oils, they can be stored long periods of time if they are protected from air, moisture and high temperature (Norris, 1979) without any significant deterioration. However, the concentration of natural tocopherols in soybean oil is too high for optimum oxidative stability and flavor, because they can act as pro-oxidants by peroxide formation (Jung & Min, 1990, Warner, 2005. Moreover, tocopherols exert several beneficial activities, such as protective role of vitamin A, -carotene and essential fatty acids (Ferrari et al, 1996).…”

Section: Soybean Oil Deodorizer Distillate Production and Characterizmentioning

confidence: 99%

Extraction and Enzymatic Modification of Functional Lipids from Soybean Oil Deodorizer Distillate

Torres¹,

Torrelo²,

Reglero³

2011

Recent Trends for Enhancing the Diversity and Quality of Soybean Products

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Effects of α‐, γ‐, and δ‐Tocopherols on Oxidative Stability of Soybean Oil

Cited by 160 publications

References 10 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 carotenoids, extracted from dry tomato waste, on the stability and characteristics of various vegetable oils

Extraction and Enzymatic Modification of Functional Lipids from Soybean Oil Deodorizer Distillate

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