Characterization of a 13-lipoxygenase from virgin olive oil and oil bodies of olive endosperms

Georgalaki, Marina; Bachmann, Astrid; Sotiroudis, Theodore G.; Xenakis, Aristotelis; Porzel, Andrea; Feußner, Ivo

doi:10.1002/(sici)1521-4133(199812)100:12<554::aid-lipi554>3.3.co;2-m

Cited by 19 publications

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“…It is already known that peroxidized fatty acids produce a number of DMPO-free radical adducts when reacted with metal ions and lipoxygenase (7,13,14). On the other hand, among a variety of olive oil pro-oxidant factors, iron and copper represent the major transition metal pro-oxidant factors of this oil (1), and we have recently reported the presence of lipoxygenase activity in virgin olive oil (15,16). In this respect, it is reasonable to assume that certain samples of virgin olive oil, such as the one in Figure 1, may contain a high ratio of pro-oxidant factors vs. antioxidant or chelating components, which will easily permit the production of free radicals detected by the DMPO spin trap.…”

Section: Resultsmentioning

confidence: 99%

Virgin olive oil: Free radical production studied with spin‐trapping electron paramagnetic resonance spectroscopy

Skoutas

Haralabopoulos

Avramiotis

et al. 2001

J Americ Oil Chem Soc

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Spin trapping using 5,5-dimethyl-1-pyrroline Noxide (DMPO) has been used to detect and distinguish free radicals in samples of Greek extra virgin olive oils. A number of the samples examined immediately after the addition of the spin trap showed a spontaneous complex electron paramagnetic resonance (EPR) signal. The majority of DMPO-radical adducts formed (80-90%) represented peroxyl and alkoxyl radical adducts. Similar spectra were recorded when DMPO was added in oxidized triolein and then treated with Fe 2+ , Fe 3+ , or Cu 2+ or when EPR-silent olive oil samples were treated with these metallic ions. Metal ion-catalyzed decomposition of triolein hydroperoxides, as recorded by EPR signal intensity, increased with increasing metal ion concentration in the micromolar range. The relative concentration of alkoxyl-DMPO adducts increased with increasing Fe 2+ or Fe 3+ concentration, whereas that of peroxyl-DMPO species decreased. In contrast, the relative concentrations of alkoxyl and peroxyl species produced by Cu 2+ were similar over the whole metal concentration range examined. Exposure of EPR-silent virgin olive oil or oxidized triolein to ultraviolet light in the presence of DMPO resulted in the detection of a three-line spectrum characterized by wide line widths.Paper no. J9852 in JAOCS 78, 1121-1125 (November 2001).KEY WORDS: Copper, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), electron paramagnetic resonance spectroscopy (EPR), free radicals, iron, olive oil, spin trapping.It has long been known that oxidative rancidity is the main deteriorative change of olive oil during storage and that it is due to the oxidation of unsaturated fatty acids and the subsequent formation of compounds possessing an unpleasant taste and odor (1). This general oxidation process affecting the stability of vegetable oils is often called autoxidation and involves a free radical mechanism. It is assumed that hydroperoxide groups attach to the carbon atom of unsaturated fatty compounds, and subsequently, the breakdown of hydroperoxides gives a chain reaction of autoxidation (2,3). Olive oil oxidation is affected by a number of factors, such as oxygen, temperature, presence of metals and chromophores, light, and ionizing radiation, whereas the resistance of virgin olive oil to oxidation is related to the high levels of monounsaturated triacylglycerols and the presence of natural antioxidants (1). Transition metals, especially iron and copper, are known contaminants of virgin olive oil and may act as pro-oxidant factors because they catalyze both the generation of free radicals and the decomposition of hydroperoxides (1-3). The oxidation of unsaturated fats is also accelerated by exposure to light, and direct photo-oxidation is due to free radicals produced by ultraviolet (UV) irradiation, which catalyzes the decomposition of hydroperoxides and other oxygen complexes of unsaturated lipids (2,3).Of the available methods for the detection of free radicals, only spin trapping offers the opportunity to simultaneously measure and distinguish amon...

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Section: Resultsmentioning

confidence: 99%

Virgin olive oil: Free radical production studied with spin‐trapping electron paramagnetic resonance spectroscopy

Skoutas

Haralabopoulos

Avramiotis

et al. 2001

J Americ Oil Chem Soc

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“…The presence of oxidizing enzyme activities, such as lipoxygenase (LOX) and polyphenol oxidase (tyrosinase), has been reported in Greek virgin olive oil samples [12,13] and olive fruit [14][15][16]. Tyrosinase (polyphenol oxidase, EC 1.14.18.1) is a copper-containing tetrameric enzyme widespread in animals, plants and microorganisms [17].…”

Section: G a L L E Y P R O O Fmentioning

confidence: 99%

Oxidation of oleuropein studied by EPR and spectrophotometry

Tzika

Papadimitriou

Sotiroudis

et al. 2008

Euro J Lipid Sci & Tech

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The autoxidation at alkaline pH and enzymatic oxidation by mushroom tyrosinase of oleuropein, the dominant biophenol present in the fruits and leaves of Olea europea, was followed by both electron paramagnetic resonance (EPR) and absorption spectroscopy. For comparison, the same oxidation processes were applied to 4-methylcatechol, a simple polyphenol present in olive mill wastewaters. EPR spectra of stable o-semiquinone radicals produced during autoxidation at pH 12 and short-lived o-semiquinone free radicals produced during autoxidation at pH 9.0 or tyrosinase action and stabilized by chelation with a diamagnetic metal ion (Mg 21 ) were recorded for both polyphenols, and the corresponding hyperfine splitting constants were determined. The UV-Vis spectral characteristics of the oxidation of polyphenols were highly dependent on the type of polyphenol, oxidant type and the pH of the reaction. The kinetic behavior of tyrosinase in the presence of oleuropein and 4-methylcatechol was followed by recording spectral changes at 400 nm (absorption maximum) over time. The tysosinase activity with oleuropein showed a pronounced pH optimum at pH 6.5 and a minor one around pH 8. From the data analysis of the initial rate at pH 6.5, the kinetic parameters K m = 0.34 6 0.03 mM and V max = (0.029 6 0.002) DA 400 min -1 were determined for oleuropein.

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“…Frega et al (1997) han encontrado que el proceso de deshuesado da lugar a un importante incremento de la estabilidad oxidativa en el AOV resultante. Este incremento de la estabilidad oxidativa podría ser debido a un menor contenido de enzimas con actividad oxidativa en el aceite, como una lipoxigenasa (LOX) que estaría presente en la semilla contenida en el hueso de la aceituna (Frega et al, 1997;Georgalaki et al, 1998). De esta forma, la semilla se comportaría como un material biológi-camente activo en la catálisis de reacciones oxidativas durante el proceso de obtención del AOV.…”

Section: Introductionunclassified

“…Una primera aproximación en este sentido sería estudiar el efecto que el proceso de deshuesado de la aceituna tiene sobre la composición del aroma del AOV, como parte integrante de la calidad organoléptica de este producto. La identificación de una actividad LOX en el endospermo de la semilla de aceituna que cataliza la producción de 13-hidroperóxido de LA (Georgalaki et al, 1998) evidencia el papel que la semilla de la aceituna puede jugar en la biosíntesis del aroma del AOV. Este hallazgo y el creciente interés que la obtención de AOV a partir de aceituna deshuesada está despertando nos ha llevado a estudiar el efecto que el proceso de deshuesado tiene sobre el aroma del AOV como parte fundamental de la calidad organoléptica de este producto.…”

Section: Introductionunclassified

The effect of olive fruit stoning on virgin olive oil aroma

Luaces¹,

Pérez²,

Sanz³

2004

Grasas y Aceites

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RESUMENEfecto del deshuesado de la aceituna sobre el aroma del aceite de oliva virgen.El deshuesado de la aceituna da lugar a una importante modificación del aroma del aceite de oliva virgen. La intensidad de esta modificación es característica de cada variedad. En los aceites obtenidos de aceitunas Verdial y Manzanilla se produce un incremento en el contenido de los compuestos de seis átomos de carbono (C6) que no se detecta en la variedad Picual. En las tres variedades estudiadas se observa un descenso del contenido de compuestos de cinco átomos de carbono (C5) así como del contenido en ésteres. En la variedad Verdial se ha comprobado que la modificación del aroma como consecuencia del deshuesado del fruto se debe tanto al daño tisular generado durante este proceso como a la ausencia de la semilla durante la molturación de la aceituna. Ambos factores contribuyen de forma independiente a la modificación del contenido de compuestos C6, C5 y ésteres en el aroma del aceite de oliva virgen procedente de aceituna deshuesada. PALABRAS-CLAVE: : Aceituna -Aroma -DeshuesadoOlea europaea -Ruta lipoxigenasa SUMMARYThe effect of olive fruit stoning on virgin olive oil aroma.Olive fruit stoning gives rise to an important modification in olive oil aroma. The level of this modification is a function of the cultivar. An increment in the content of six-carbon compounds (C6) was observed in olive oils obtained from the cultivars Verdial and Manzanilla, but not in the cultivar Picual. In the three cultivars under study, contents of five-carbon compounds (C5) and esters decreased as a consequence of fruit stoning. The modification of olive oil aroma composition in the cultivar Verdial caused by olive fruit stoning was observed to be due both to tissue wounding and to the absence of the olive seed during the crushing-malaxation process to obtain olive oil aroma. Both factors contribute independently to the content modification of C6, C5 compounds and esters in the olive oil aroma from stoned fruits. KEY-WORDS:Aroma -Lipoxygenase pathway -Olea europaea -Olive -Stoning. INTRODUCCIÓNEl consumo de aceite de oliva virgen (AOV) se está incrementando a nivel mundial de forma continua, no sólo por sus propiedades nutritivas sino también por sus particulares características organolépticas que hacen a este producto único dentro del ámbito de las grasas alimentarias. La obtención de un producto de alta calidad ha estimulado la investigación hacia el desarrollo de innovaciones tecnológicas que, sin embargo, deben ser cuidadosamente evaluadas antes de ser aplicadas a nivel industrial. En este sentido, recientemente se está desarrollando una nueva tecnología en el proceso de obtención del AOV que conlleva la retirada del hueso de la aceituna antes de su molturación. Frega et al. (1997) han encontrado que el proceso de deshuesado da lugar a un importante incremento de la estabilidad oxidativa en el AOV resultante. Este incremento de la estabilidad oxidativa podría ser debido a un menor contenido de enzimas con actividad oxidativa en el aceite, co...

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Characterization of a 13-lipoxygenase from virgin olive oil and oil bodies of olive endosperms

Cited by 19 publications

References 0 publications

Virgin olive oil: Free radical production studied with spin‐trapping electron paramagnetic resonance spectroscopy

Virgin olive oil: Free radical production studied with spin‐trapping electron paramagnetic resonance spectroscopy

Oxidation of oleuropein studied by EPR and spectrophotometry

The effect of olive fruit stoning on virgin olive oil aroma

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