Calidad nutricional y contenido fitoquímico de aceites prensados en frío de semillas de chía, cardo mariano, nigella, y amapola blanca y negra

Cold pressed oils obtained from chia (Salvia hispanica L.), milk thistle (Silybum marianum L.), nigella (Nigella sativa L.), and white and black varieties of poppy (Papaver somniferum L.) seeds were character­ized. The nutritional quality was determined based on the analysis of fatty acids, tocochromanol and phytos­terol contents, as well as antioxidant activity and general physico-chemical properties. Among the oils analyzed the fatty acid composition most beneficial for health was found in chia seed oil, with 65.62% of α-linolenic acid and the n-6:n-3 fatty acid ratio of 1:3.5. Other oils studied were rich sources of linoleic acid (18.35-74.70%). Chia seed oil was also distinguished by high contents of phytosterols, mainly β-sitosterol (2160.17 mg/kg oil). The highest content of tocochromanols was found in milk thistle oil with dominant α-tocopherol (530.2 mg/kg oil). In contrast, the highest antioxidant activity was recorded for nigella oil (10.23 μM Trolox/g), which indi­cated that, in addition to tocopherols, other antioxidants influenced its antioxidant potential.Se caracterizaron aceites prensados en frío obtenidos de semillas de chía (Salvia hispanica L.), cardo mariano (Silybum marianum L.), nigella (Nigella sativa L.) y de variedades blancas y negras de amapola (Papaver somniferum L.). La calidad nutricional se determinó en base al análisis de ácidos grasos, el contenido de tococromanoles y fitosteroles, así como la actividad antioxidante y las propie­dades fisicoquímicas generales. Entre los aceites analizados, la composición de ácidos grasos más beneficiosa para la salud se encontró en el aceite de semilla de chía, con un 65,62% de ácido α-linolénico y una relación de ácido graso n-6:n-3 de 1:3,5. Los demás aceites estudiados fueron ricos en ácido linoleico (18,35-74,70%). El aceite de semilla de chía también se distinguió por el alto contenido de fitosteroles, principalmente β-sitosterol (2160,17 mg/kg de aceite). El mayor contenido de tococromanoles se encontró en el aceite de cardo mariano con α-tocoferol dominante (530,2 mg/kg de aceite). Por el contrario, se registró la mayor actividad antioxidante para el aceite de nigella (10,23 μM Trolox/g), lo que indica que, además del tocoferol, otros antioxidantes influyeron en su potencial antioxidante

Cromatografía en columna como método para la eliminación de componentes menores del aceite de colza

The purpose of this study was to verify the influence of different chromatographic column beds (silicic acid, activated charcoal, aluminum oxide, silica gel) on the concentration of individual minor components (sterols, tocopherols, carotenoids and chlorophyll) in rapeseed oil. With the use of a combination of these beds, a three-stage optimized method for removing minor components from rapeseed oil was developed. It was demonstrated that the combination of silicic acid and activated charcoal removed about half of the sterols present from the oil. Aluminum oxide turned out to be the most effective bed in removing tocopherols, purifying the oil to their minimum level (2.6 mg/kg). All adsorbents used had similar capacity to purify oil from pigments (carotenoids and chlorophyll). In the three-stage purification process free sterols were almost completely removed (to the level 90.0 mg/kg). Purification of β-carotene and chlorophyll from the oil was also very effective. Tocopherols were completely removed with this method, except for a small amount of α-tocopherol (0.4 mg/kg), which results from its relatively weak interaction with a hydrophilic bed. The developed method may be used in studies on the effect of association colloids on bulk oil autoxidation processes.El propósito de este estudio fue verificar la influencia de diferentes rellenos de columnas cromatográficas (ácido silícico, carbón activo, óxido de aluminio, gel de sílice) sobre la concentración de componentes menores individuales (esteroles, tocoferoles, carotenoides y clorofila) en aceite de colza. Gracias a esto, se desarrolló un método optimizado de tres etapas para eliminar los componentes secundarios del aceite de colza (utilizando una combinación de todos los rellenos descritos anteriormente). Se ha demostrado que con la combinación de ácido silícico y carbón activo se elimina del aceite alrededor de la mitad de los esteroles presentes. El óxido de aluminio resultó ser el relleno más eficaz para eliminar los tocoferoles, purificando el aceite hasta su nivel mínimo (2,6 mg/kg). Todos los adsorbentes utilizados tenían una capacidad similar para purificar el aceite de pigmentos (carotenoides y clorofila). En el proceso de purificación en tres etapas, los esteroles libres se eliminaron casi por completo (hasta el nivel de 90,0 mg/kg). La purificación de aceite de β-caroteno y clorofila también fue muy efectiva. En este método, los tocoferoles se eliminaron completamente, excepto pequeñas cantidades de α-tocoferol (0,4 mg/kg), lo que resulta de su interacción relativamente débil con un relleno hidrófilo. El método desarrollado se puede usar en los estudios sobre el efecto de los coloides de asociación en los procesos de autooxidación de aceites a granel

The Interactions Between Rapeseed Lipoxygenase and Native Polyphenolic Compounds in a Model System

The focus of the present research was to study inhibition of lipoxygenase activity by rapeseed native polyphenols and the interactions between those compounds and the enzyme. The enzyme and polyphenolic compounds (polyphenols, phenolic acids) were extracted from rapeseed (Brassica napus) varieties Aviso and PR45DO3. The total phenolic compounds concentration in tested rapeseed was 1,485–1,691 mg/100 g d.m. (dry matter) and the free phenolic acids content in both rapeseed varieties was about 76 μg/100 g d.m. The isolated proteins showed lipoxygenase activity. Prooxidant properties of phenolic compounds in the presence of lipoxygenase and linoleic acid were observed rather in the case of extracts containing a relatively high concentration of miscellaneous polyphenols. Antioxidant properties were recorded in the case of phenolic acid extracts which contain only 1.4–1.9% of phenolics present in raw phenolic extracts. We propose that the prooxidant effect of phenolic compounds comes from quinone and oxidized polyphenols formation. The observed antioxidant activity of phenolic acid extracts is probably due to their ability to scavenge free radicals formed from linoleic acid. However, reduction of lipoxygenase ferric to ferrous ions, which prevent the activation of the enzyme and inhibited its activity, was also observed

Applying quantum dots to determine food components and contaminants

Kropki kwantowe (QD) są półprzewodnikowymi nanostrukturami o średnicy 1 ÷ 100 nm, zdolnymi do fotoluminescencji. W roztworach oddziaływania pomiędzy atomami na powierzchni kropki kwantowej i otaczającymi je cząsteczkami mogą w istotny sposób wpływać na fotoluminescencje QD. Właściwość ta jest podstawą wykorzystania kropek kwantowych w analityce. Często stosuje się modyfikacje kropek kwantowych poprzez powlekanie ich powierzchni związkami zdolnymi do oddziaływania z analitem. Zastosowanie kropek kwantowych umożliwia opracowania nowych, czułych, selektywnych i szybkich metod analitycznych. W pracy przedstawiono metody oznaczania sacharydów, peptydów i białek, kwasu askorbinowego, związków fenolowych oraz zanieczyszczeń żywności i substancji niepożądanych. Opisano także szereg mechanizmów oddziaływania kropek kwantowych z oznaczanymi substancjami.Quantum dots (QD) are semiconductor nanostructures of a diameter between 1 and 100 nm, capable of photoluminescence. In solutions, interactions occurring between the atoms on the surface of a quantum dot and the neighbouring molecules can significantly affect the photoluminescence of QD. Owing to this characteristic, quantum dots are utilized in analytical methods. Modified quantum dots are often used; their modification consists in coating their surface using molecules capable of interacting with an analyte. The use of quantum dots makes it possible to develop novel, sensitive, selective, and quick analytical methods. In the paper, some methods are described, which are used to determine saccharides, peptides, proteins, ascorbic acid, phenolic compounds, food contaminants, and undesirable substances. Furthermore, some mechanisms are depicted of the interaction between quantum dots and an analyte

Antioxidant synergism and antagonism between tocotrienols, quercetin and rutin in model system

The aim of the study was to reveal antioxidant synergism or antagonism between quercetin, rutin and selected tocotrienols in linoleic acid emulsion. The oxidative stress was generated by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) or CuSO4; the increase of the concentration of peroxidation products was monitored using fluorescence probe 2,7-dichlorofluorescein (DCF). The antioxidant activity of tested substances depends on the form of the antioxidant (aglycone, glycoside), its concentration, localization in the emulsion, and the factors generating oxidative stress. The synergistic effect occurred when the effectiveness of individual antioxidant was relatively weak and mainly when the concentration of antioxidants was in the physiologically significant range of 1 μM. We suggest that tocotrienols were regenerated by flavonoids. The synergism benefitted from the proximity of the localization of interacting antioxidants (e.g. the presence of one of the antioxidants at the oil-water interface)

Chemical Composition of Seed Oils Recovered from Different Pear (Pyrus communis L.) Cultivars

Lipophilic bioactive compounds in oils recovered from the seeds of eight pear (Pyrus communis L.) cultivars were studied. Oil yield in pear seeds ranged between 16.3 and 31.5 % (w/w) dw. The main fatty acids were palmitic acid (6.13–8.52 %), oleic acid (27.39–38.17 %) and linoleic acid (50.73–63.78 %), all three representing 96–99 % of the total detected fatty acids. The range of total tocochromanols was between 120.5 and 216.1 mg/100 g of oil. Independent of the cultivar, the γ-tocopherol was the main tocochromanol and constituted approximately 88 %. The contents of the carotenoids and squalene were between 0.69–2.99 and 25.5–40.8 mg/100 g of oil, respectively. The β-sitosterol constituted 83.4–87.6 % of total sterols contents, which ranged between 276.4 and 600.1 mg/100 g of oil. Three significant correlations were found between oil yield and total contents of sterols (r = −0.893), tocochromanols (r = −0.955) and carotenoids (r = −0.685) in pear seed oils