Oxidation Of Sunflower Oil Research Articles

Sea Buckthorn Seed Powder Provides Protection in the Oxidative Stress Produced by Thermally Oxidized Sunflower Oil in Rabbits

SBT seed powder was used against the oxidative stress produced by thermally oxidized sunflower oil. OSFO and SBT powder were orally administered to the rabbits. Blood biochemistry, hematology and liver pathology were investigated. The results show that OSFO produce changes in the blood biochemistry and hematology and alterations in the liver. However, the toxicity of OSFO was minimized when rabbits were fed with SBT seed powder. The SBT seed both in independent and in fortified forms significantly decreases the serum cholesterol, LDL-c, ALT (alanine aminotransferase) and TG values, whereas it increases serum glucose and HDL-c values. The seed powder normalizes all the hematological indices. Histopathological investigation of the liver reveals that OSFO intake causes severe adverse changes, whereas SBT seed powder was found to restore the normal condition. It was concluded that SBT seed powder has strong potential to reduce the toxicity of oxidized lipids in model animals. Practical Applications Thermally oxidized edible oils are one of the main concerns of the modern-day food chemists and technologists. The ingestion of these oxidized lipids results into the toxic effects on human beings. This study clearly showed for the first time that SBT seed powder reduces the degenerative and toxic changes in the liver produced by thermally oxidized lipids. It has been found that SBT seed powder supplementation has protective effects against the toxicity of OSFO by increasing the antioxidant potential.

Properties of model systems of sunflower oil and green coffee extract after heat treatment and storage

Model systems of sunflower oil and green coffee extract (GCE) were examined. GCE was added to the oil at 3 g/100 g. Complex systems of the oil with saccharose, starch and egg white protein were studied. Samples were heated at 110 °C or 180 °C for 60 min and stored for 3 months. The research was aimed at determining the effects of high concentrations of green coffee antioxidants on the oxidative status of fatty acids and antioxidant activity of the systems depending on their composition. The fatty acid profile using the GC-FID method and peroxide value of sunflower oil as well as potentiometric determination of redox potential and the DPPH radical scavenging ability of model systems were analyzed. The obtained results showed a limiting of oxidation of sunflower oil heated with 3 g/100 g of GCE alone and in more complex systems. The average inhibition degree was 65% when compared to analogical non-enriched systems. The research also concluded that, despite prolonged heating and storage, these systems exhibited a significantly higher (P < 0.05) antioxidant activity in a test with DPPH when compared to those without GCE.

English

Sunflower oil is extensively used in frying in Algeria as an alternative to olive oil due to its low cost. However, the high level of unsaturated fatty acids (FA) contained in sunflower oil enhances its susceptibility to oxidation. In our study, the sunflower oil was heated at 99&plusmn;2&deg;C with incorporation of 9 L of oxygen/second for 52 h continuously in the absence of foodstuff. Heating polyunsaturated fatty acids (PUFAs) in the presence of air causes a greater degree of lipid peroxidation. The oil oxidation degree was monitored through several physicochemical analyses. The products of thermal oxidation were monitored using UV- spectrophotometric method and Fourier transform infrared spectroscopy (FT-IR). Compared to fresh oil, the free-fatty acid contents, peroxide value, density and moisture of the thermally oxidized sunflower oil increased. In addition, the iodine and saponification values decreased during thermal treatment. The treatment applied had a negative effect on FA composition; the most significant effects were on C18:2, C18:1 and C16:0 contents. Analysis of chromatographic profile of thermoxidized sunflower oil showed a reduction in linoleic acid (LA) and an increase in oleic and palmitic acids; decrease of linoleic acid content is used as an indicator of lipid oxidation. Moreover, during the early stages, conjugated dienes (CDs), absorbing at 233 nm, were formed upon decomposition of hydroperoxides. In our study, the early stages of lipid oxidation were measured by UV-spectrophotometric method. Hydroperoxides broke down into secondary products and were revealed by FT-IR; these scission products are generally odoriferous by nature. The C=O stretching band at 1739-1724 cm-1 of the aldehydes was much more intense. Formation of conjugated double bond systems and the isomerisation of cis to trans double bonds was observed in the C=C stretching region at 980 to 965 cm-1. The results obtained reveal that even fresh oil contains products of peroxidation and isomerization of C18:2, n-6; indeed, CDs can be produced during the refining process of oil. The treatment applied increased the rate of these products and conferred a marked rancid taste and a thick texture to the thermoxidized sunflower oil. &nbsp; Key words: Sunflower oil, Linoleic acid, thermally oxidative treatment, alteration level.&nbsp;

Cardiotoxicity induced by dietary oxidized sunflower oil in rats: pro- and antioxidant effects of α-tocopherol.

This study highlighted the pro-oxidative functions of α-tocopherol (αT) on the heart antioxidant system and tissue histopathology of oxidized sunflower oil (OSO)-exposed rats.Four groups of male Wistar rats were fed with different diets: 1) control diet containing FSO (fresh sunflower oil); 2) diet containing 5 % OSO; 3) diet containing 5 % OSO, supplemented with 600 mg αT kg-1; and 4) diet containing 5 % OSO, supplemented with 1200 mg αT kg-1. The hearts were then isolated, and the antioxidant enzymatic activities were assessed. Body weight and catalase (CAT), glutathione peroxidase (GPx) activities significantly decreased in groups fed with OSO, while the lipid peroxidation (LPO) level significantly increased. Administration of OSO with αT (600 mg · kg-1) returned the body weight values and LPO levels to similar values as the control group. The CAT and GPx activities increased but remained significantly lower compared to the control group. In the OSO group with αT (1200 mg · kg-1), the CAT and GPx activities also decreased, while LPO significantly increased. Heart tissue sections obtained from the groups revealed the presence of large areas of necrosis. This study suggested that OSO induced oxidative stress and that administration of a moderate dose of αT restored the antioxidant balance, but that high levels of αT supplementation result in a pro-oxidant effect.

Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives

(−)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives were prepared by lipase catalyzed acylation of EGCG with vinyl acetate to improve its lipophilicity and expand its application in lipophilic media. The immobilized lipase, Lipozyme RM IM, was found to be the optimum catalyst. The optimized conditions were as follows, 1:1 of the molar ratio of EGCG to vinyl acetate, 2.0% (w/w of both substrates) of enzyme amount, and 84.5% conversion was obtained after 8h reaction at 40°C in acetonitrile. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG were confirmed by LC–MS–MS and the tri-acetylated EGCG was identified as 5′,3″,5″-3-O-acetyl-EGCG by NMR. Their enhanced lipophilicity was confirmed by octanol–water partition coefficient. The antioxidant activity of the acetylated EGCG derivatives were superior to butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and EGCG as determined by peroxide values (POVs) in sunflower oil as well as by the p-anisidine method. Acetylated EGCG exhibited the highest 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC50 of 0.09mg/mL) compared to EGCG, BHT and TBHQ. Acetylated EGCG might be used as a potent antioxidant for controlling oxidation of sunflower oil.

Interaction of Light and Temperature on Tocopherols During Oxidation of Sunflower Oil

AbstractLight and temperature effects on tocopherols during the oxidation of sunflower oil were studied. The oxidation was performed at 40, 60, or 80 °C for 30, 15, and 6 days, respectively, in the dark or under 1,700 lux light. Oil oxidation was analyzed with peroxide values and conjugated dienoic acid contents, and tocopherols in the oil were separated and quantified by HPLC. The oxidation of sunflower oil was increased with temperature increase, and the light decreased the temperature dependence of the oil oxidation. Sunflower oil before oxidation contained tocopherols with a total of 737.96 mg/kg, with α‐ and γ‐tocopherol at 726.41 and 11.56 mg/kg, respectively, and the tocopherol contents decreased during the oil oxidation. Degradation of tocopherols increased with the temperature increase, and its dependence on the temperature was lower under light than in the dark. γ‐Tocopherol showed higher stability than α‐tocopherol during oxidation of the oil in the dark and under light. Residual amounts of tocopherols showed a relatively good correlation with the degree of oil oxidation, and the dependence of α‐tocopherol degradation on the oil oxidation was higher than that of γ‐tocopherol, and light decreased the dependence on the oil oxidation in both tocopherols.

Effect of ingestion of thermally oxidized sunflower oil on the fatty acid composition and histological alteration of rat liver and adipose tissue in development

The effect of ingestion of thermoxidized sunflower oil (TOS) on fatty acids composition and histological alteration was investigated in rats. The animals were divided into 2 groups, the first group fed on fresh sunflower oil (FSO) diet and a second group fed on TOS diet during 9 weeks. This oil was heated at 99 ± 2°C with incorporation of 9 L of oxygen/second during 52 h continuously. Changes that occurred in oil fatty acid composition were similar to those found in tissues (liver and adipose tissue) of rat, nourished with oxidized oil. Indeed, our results showed a change in the tissues profile of the fatty-acids; the rates of saturated and monounsaturated fatty-acids increased with the detriment of the linoleic acid and its higher derivative, arachidonic acid. Thus, the total unsaturation of the tissues lipids decreased. In addition, unlike linoleic acid, the palmitic acid is converted into C16:1 n-7. Probably, this was due to the activation of Δ9-desaturase and the reduction of the Δ6- and Δ5-desaturases by the generated products in thermoxidized sunflower oil. Microscopic examination of the test group showed a significant histological change, when compared with the control, such as increase in cell size. Key words: Thermoxidized sunflower oil, rat, fatty acid composition, histology, tissues.

Enhancing oxidative stability of sunflower oil during convective and microwave heating using grape seed extract.

This study was performed to investigate the effectiveness of grape seed extract (GSE) compared to butylated hydroxytoluene (BHT) on retarding lipid oxidation of sunflower oil subjected to convection and microwave heating up to 240 min under simulated frying conditions. The progress of lipid oxidation was assessed in terms of peroxide value (PV), p-anisidine value (p-AV), conjugated dienes and trienes (CD, CT), inhibition of oil oxidation (IO) and TOTOX value. In addition, total phenolic content (TP) was evaluated in samples before and after heating in order to assess the changes in these compounds relative to the extent of lipid oxidation. The results of this study highlight that GSE showed a significantly inhibitory effect on lipid oxidation during both treatments, although to a different extent. This ability was dose-dependent; therefore, the extent of lipid oxidation was inversely related to GSE level. Convective heating, respective microwave exposure for 240 min of samples supplemented by GSE to a level of 1000 ppm, resulted in significant decreases of investigated indices relative to the control values as follows: PV (48%; 30%), p-AV (29%; 40%), CD (45%; 30%), CT (41%; 36%), TOTOX (35%; 37%). GSE to a level of 600–800 ppm inhibited the lipid oxidation in a similar manner to BHT. These results suggested that GSE can be used as a potential natural extract for improving oxidative stability of sunflower oil during thermal applications.

Antioxidant activity of arylhydrazones in sunflower oil oxidation

Antioxidant properties of arylhydrazones in sunflower oil oxidation and regular trends in variation of the antioxidant activity of arylhydrazones in the process in comparison with ethybenzene oxidation were examined.

Assessment of the oxidative stability of conventional and high-oleic sunflower oil by means of solid-phase microextraction-gas chromatography

Headspace-solid-phase microextraction-gas chromatography (HS-SPME-GC) was used to identify in total 74 volatile lipid oxidation compounds altogether in thermally stressed conventional and high-oleic sunflower (HOSF) oil samples (in accelerated storage conditions for 14 days at 80°C). Out of the volatile compounds identified, six volatile compounds were selected as marker compounds for the assessment of lipid oxidation of sunflower (SF) and HOSF oils due to their low odour threshold values and fatty-rancid odour impression. Additionally, other oxidation parameters such as fatty acid composition, peroxide value (PV), anisidine value and tocopherol and tocotrienol composition were determined. Multivariate statistical methods (principal component analysis and agglomerative hierarchical cluster analysis) were applied to identify sensitive oxidation marker compounds. Preliminary results revealed that hexanal, E-2-heptenal, E-2-decenal and E,E-2,4-nonadienal were the most suitable in differentiating HOSF and SF oil varieties from each other and SF samples with differing oxidative properties. Differentiation of SF samples according to their volatile compound composition was done in accordance with the results from the well-known oil quality parameters (e.g. PV or fatty acid composition). In conclusion, the combination of volatile compound analysis with HS-SPME-GC and multivariate statistical methods provides a sensitive tool in differentiating conventional SF and HOSF oils by means of volatile lipid oxidation marker compounds.

Antioxidant activity of amino acids during oxidation of sunflower oil in an emulsion

The influence of α-amino acid additions on the process of sunflower oil oxidation in oil—water emulsions was investigated. It is established that both amino acids and their salts (hydrochlorides) exhibit an antioxidant effect. The antioxidant action of amino acids increases with an increasing number of nitrogen atoms in the molecule. The amino group is a reactive center at which the process of oil oxidation in the emulsion is inhibited. Amino acids and their salts (hydrochlorides) act on the oil—water interface so as to accelerate the disintegration of lipid peroxide compounds in the water—oil system with the formation of molecular products.

Interaction of Phosphatidylcholine and α‐Tocopherol on the Oxidation of Sunflower Oil and Content Changes of Phosphatidylcholine and Tocopherol in the Emulsion under Singlet Oxygen

Interaction of phosphatidylcholine (PC) and α-tocopherol (α-Toc) on the oxidation of oil in the emulsion consisting of sunflower oil and water under singlet oxygen at 25 °C was studied by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. Singlet oxygen was produced by chlorophyll b under 1700 lux. Single addition of PC or α-Toc decreased the values of peroxides and CDAs of oil in the emulsion via singlet oxygen quenching. PC and α-Toc showed simply additive interaction in decreasing the singlet oxygen oxidation of oil in the emulsion. α-Toc was a physical quencher of singlet oxygen in the emulsion, but PC involved chemical quenching in the antioxidant action. Chlorophyll and PC contents were decreased in the emulsion under singlet oxygen, while α-Toc was not. α-Toc protected chlorophyll and PC from degradation, and was a more important component than PC in the oil oxidation under singlet oxygen in the emulsion.

Characterization of Vegetable Oils by Fluorescence Spectroscopy

Results presented in this paper show the ability to analyze vegetable oils with very cheap and easy method based on fluorescence spectroscopy. We have recorded, with a very simple experimental set up, fluorescence spectra for several vegetable oils at excitation wavelength λex = 370 nm. After deconvolution, using a Lorentzian profile, and identification of the stripes forming the spectra, a normalization of the intensities was made with respect to the vitamin E band with λ= 525 nm taken as reference. A statistical method based on Principal Component Analysis (PCA) is used to emphasize differences between refined and unrefined oils. We also noticed a significant difference between fluorescence of the argan cosmetic oil and edible argan oil due to the heating of the second one during its preparation. Stability to thermal oxidation of high oleic sunflower oil compared to the extra virgin olive, argan cosmetic and refined corn oils is also shown.

Photoinduced and thermal oxidation of rapeseed and sunflower oils

The aim of the present study was to compare oxidative stability of different sunflower and rapeseed oils. Ultra violet (UV) irradiation was used as an accelerator of the oil oxidation process. After UV irradiation, the formed volatile compounds were extracted by headspace solid-phase microextraction HS-SPME (DVB/CAR/PDMS fibre) and analysed by gas chromatography coupled with a flame ionization detector (GC/FID). At the same time, the same oil samples were thermally oxidized. The induction periods were determined on the basis of hexanal to 2-trans-nonenal ratio in the analysed samples. Finally, the obtained results were compared with induction period values obtained through the determination of peroxide and anisidine values, and from the Rancimat method, manostatic test and differential scanning calorimetry (DSC) method. The results obtained using the new method were well correlated with those achieved with the well-established analytical techniques. The values of the induction period obtained after UV/HS-SPME/GC/FID were up to three times higher than those from Rancimat, but the correlation between these two methods was on a very good level (correlation coefficient R>0.98). Similar correlation was also observed between these new methods and the DSC or manostatic test. In all cases, better results were obtained for rapeseed oils than sunflower oils.

Moderately Oxidized Oils and Dietary Zinc and α-Tocopheryl Acetate Supplementation: Effects on the Oxidative Stability of Rabbit Plasma, Liver, and Meat

The aim of this study was to assess the alterations in plasma, liver, and meat oxidative stability and α-tocopherol content when moderately oxidized sunflower oils were added to feeds and when feeds were supplemented with α-tocopheryl acetate (100 mg/kg) and Zn (200 mg/kg). The effects of cooking the meat and its subsequent refrigeration were also studied. When the content of primary oxidation compounds of the oil was high, rabbit plasma, liver, and meat α-tocopherol content was reduced and meat susceptibility to oxidation increased. The addition of oil with a high content of secondary oxidation compounds (oil heated at 140 °C, 31 h) to feed also led to an increase in meat susceptibility to oxidation, although it presented an α-tocopherol content similar to that of nonheated oil. Feed supplementation with α-tocopheryl acetate increased tissue α-tocopherol content and improved the oxidative stability of liver and meat. However, in the latter, it was less effective when oil heated at 55 °C was added.

Gastric Emptying and Short-Term Digestibility of Thermally Oxidized Sunflower Oil Used for Frying in Fasted and Nonfasted Rats

Four-hour in vivo digestibility of sunflower oil used in frying was tested in fasted and nonfasted rats. For three consecutive days, 12 male Wistar rats received 1 g of unused oil (controls, C), while 12 received 1 g of used oil (test group, T). On the night of day 3, 6 rats from each group were fasted (FC, FT) while the other 6 animals from each group had free access to food (NFC, NFT). On day 4, FC and NFC received 2 g of unused oil, while FT and NFT received 2 g of used oil. Luminal gastric and intestinal fats were studied by column and HPSE chromatography after endogenous corrections. Gastric emptying in FT was significantly slower than in NFT and FC. The luminal gastric fat profile differed from that of the oils administered, suggesting that nonoxidized triacylglycerols passed quickly into the intestines. All glyceridic compounds present in the luminal intestinal fat were affected by oil type (at least P < 0.01). Oil digestibility value order was FT < NFT < FC < NFC. FT and NFT presented lower (P < 0.001) triacylglycerol polymer and dimer digestibilities than NFC and FC. In conclusion, oil type determined luminal intestinal fat compounds and their digestibility more than nutritional status.

Dietary lipid oxidation and vitamin E supplementation influence in vivo erythrocyte traits and postmortem leg muscle lipid oxidation in broiler chickens

The present work aimed to assess: (1) whether the oxidative status of dietary lipids or vitamin E supplementation influences in vivo erythrocyte integrity of chickens, and (2) whether erythrocyte stability is related to musculus iliotibialis susceptibility to lipid peroxidation. Thirty-six broilers were fed a basal diet supplemented with: sunflower oil (SO), sunflower oil and α-tocopheryl acetate (SO + E), and oxidized sunflower oil (SO-OX). In vivo hemolysis rate (HR) and thiobarbituric acid reactive substances (TBARS) of erythrocytes were measured. Postmortem, the TBARS of m. iliotibialis was determined. Erythrocyte HR and TBARS were higher in SO-OX than SO and SO + E groups (P &lt; 0.001). Erythrocyte and muscle TBARS were highly correlated (r2 &gt; 0.93). The SO-OX induced negative effects, indicating that dietary lipid quality is rapidly translated in negative effects to erythrocytes and muscle. In vivo erythrocyte TBARS proved to be a good indicator of meat oxidative status. Key words: Broiler, vitamin E, lipid oxidation, TBARS, erythrocytes, hemolysis

Analysis of Hydroperoxides, Aldehydes and Epoxides by1H Nuclear Magnetic Resonance in Sunflower Oil Oxidized at 70 and 100 °C

A global study of sunflower oil oxidation at two different temperatures (100 and 70 degrees C) with aeration was carried out by (1)H nuclear magnetic resonance ((1)H NMR), paying attention not only to the degradation of the main components but also to the formation of others. The functional groups of compounds monitored simultaneously during the oxidation were, in addition to acyl groups, the following: hydroperoxides, conjugated dienic systems of hydroperoxy acyl groups, aldehydes including the genotoxic and cytotoxic oxygenated alpha,beta-unsaturated aldehydes, and mono- and diepoxides. Chemical shifts of protons of all mentioned groups were given. Differences between both oxidation processes were found from the initial stages to the end. The formation of diepoxides in the oxidation process of edible oils was shown for the first time, as was the influence of temperature on the formation of epoxy acyl groups, some of these latter related to leukotoxin and isoleukotoxin.

Effects of selenium supplementation on lipid peroxidation induced by thermally oxidized sunflower oil

Effects of selenium supplementation on lipid peroxidation induced by thermally oxidized sunflower oil

Fasting Status and Thermally Oxidized Sunflower Oil Ingestion Affect the Intestinal Antioxidant Enzyme Activity and Gene Expression of Male Wistar Rats

The effect of thermally oxidized sunflower oil ingestion on antioxidant levels, enzyme activities and expressions in the small intestine of fed and fasted rats was studied. For three consecutive days, 12 male Wistar rats received 0.5 g of unused sunflower oil/100 g of body weight (controls, C) while another 12 were given 0.5 g of thermally oxidized sunflower oil/100 g of body weight (test group, T). On the night of day 3, 6 rats from each group were fasted (FC and FT, respectively) while the other 6 animals from each group were given free access to food (NFC and NFT, respectively). On day 4, FC and NFC rats received 1 g of unused oil/100 g of body weight, while FT and NFT rats were given 1 g of altered oil/100 g of body weight. Small intestines were extracted after 4 h exposure to the oils. Fasting and oil alteration significantly interacted modifying total, Se-GPx (both, P < 0.001) and non-Se-GPx (P < 0.05) activity, and GPx and Cu,Zn-SOD expressions (both P < 0.001). FT rats showed a significant increase in TBARS (P < 0.05) and catalase activity (P < 0.001) and a decrease in SOD, Se- and non-Se-dependent GPx activities (at least, P < 0.05) with respect to FC and NFT animals. SOD and GPx expressions decreased (p<0.001) but that of TNFalpha increased significantly (P < 0.001) in FT rats with respect to FC and NFT animals. Lengthy fasting and consumption of food containing oxidized fat should both be avoided to prevent intestinal oxidative stress.