Oxidative Stability Of Sunflower Oil Research Articles

EFFECT OF DIRECT APPLICATIONS OF SAGE (SALVIA OFFICINALIS L.) LEAVES ON OXIDATIVE STABILITY OF SUNFLOWER OIL DURING ACCELERATED STORAGE

ABSTRACT In this study, various sage applications were examined on oxidative stability of sunflower oil during accelerated storage. There are three applications: (1) direct sage leaves (S); (2) deodorized sage leaves (DeS); and (3) essential oil of sage leaves. The main compounds of essential oil were identified asα‐thujone (35.87%),β‐thujone (14.41%), 1,8‐cineol (10.59%) and camphor (10.09%). Oxidative stability of these three applications was tested by Schall Oven test at 60C applying peroxide value and conjugated dienes, and Rancimat at 110C. Whereas the highest antioxidants activity was found for 2% S followed by 0.5% S and 2% DeS, all sage treatments statistically retarded the oxidation compared with the control sample. The most appealing result was that the residue can be used as a natural antioxidants. That means the reuse of residue may decrease economic losses and health risk in comparison with synthetic antioxidants and extracts because it is completely natural and contains no residual solvent.PRACTICAL APPLICATIONSWhile almost all of previous studies were concentrated on the use of herb extracts, our study investigates the results of direct application of sage on oxidation. Especially with this study, we have evaluated a possible application area for sage residue leftover after the deodorization process.

Oxidative stability of sunflower oil supplemented with carnosic acid compared with synthetic antioxidants during accelerated storage

In vitro antioxidant activities and protective effects in stabilising sunflower oil of three rosemary extracts high in carnosic acid (CA) were tested. The CA contents (w/w) of the extracts were 24.9% (CA25), 60.5% (CA60) and 98.3% (CA98). Total phenolic contents of CA25 and CA60 were (3.58 ± 0.026 g/100 g) and (8.20 ± 0.027 g/100 g), (3.91 ± 0.029 g/100 g) and (8.10 ± 0.056 g/100 g) expressed in gallic acid and catechin equivalents, respectively. Reducing power of CA and other antioxidants at 0.5 mg/ml followed the order of l-ascorbic acid > CA98 > TBHQ > BHA > CA60 > BHT > CA25. The IC50 values in the DPPH assay obtained for CA25, CA60, CA98, BHA, BHT and TBHQ were 0.30 ± 0.002, 0.20 ± 0.003, 0.12 ± 0.002, 0.19 ± 0.002, 0.42 ± 0.010, and 0.09 ± 0.001 mg/ml, respectively. Protective effects of CA in stabilising sunflower oil were tested, compared to synthetic antioxidants, by measuring their peroxide values, thiobarbituric acid-reactive substances, free fatty acid contents and p-anisidine value during accelerated storage. Results indicated that CA exhibited stronger antioxidant activity in sunflower oil than BHT and BHA. However, its antioxidant activity was less than that of TBHQ.

UTILIZATION OF PEACH AND TOMATO WASTES AS UNCONVENTIONAL SOURCES OF EDIBLE OILS AND NATURAL ANTIOXIDANTS

Recycling some waste materials especially, peach and tomato seeds to beneficial materials with high nutritional and functional properties as well as, unconventional sources of edible oils with highly antioxidative properties was the main target of this study. The obtained results revealed that peach seeds had the highest content of oil (43.5 %), and the chemical properties were in the normal range of edible oils. The percentage of the unsaturated fatty acids of peach and tomato seeds oils were high (92.677 and 83.370 %, respectively) especially , essential fatty acids ( Unoleic , Omega 6 ), which reflects good nutritional value of these oils. The oxidative stability of sunflower oil increased with increasing the levels of peach methanolic extract up to 400 ppm that exhibited the best oxidative stability and prolonged the shelf life of sunflower oil to 12.5 months. The highest oxidative stability ( 8.84 hr.) was obtained using tomato methanolic extract at level of 600 ppm compared with those obtained with other levels . Shelf life and antioxidant activity of sunflower oil increased gradually with increasing the tomato methanolic extract levels (11.03 to 12.67 hrs and 1.02 to 1.18, respectively). Furthermore, lycopene crude extract acted as pro-oxidant in higher levels, meanwhile, lower levels of lycopene extract (20 and 40 ppm) had an antioxidant effects on the stability of sunflower oil. From the obtained results, it could be concluded that peach and tomato seeds are considered rich sources of edible oils and natural antioxidants that play a great role in protecting human body. Utilization of these wastes will improve the environmental ecology of industry by recycling its by-products and decrease the problems of pollution from industrial wastes .

Antioxidant properties of methanolic extracts from different parts of Sclerocarya birrea

SummaryThe methanolic extracts from Sclerocarya birrea leaves (SCL), roots (SCR), barks (SCB), and kernel oil cake (SCK) were examined for radical scavenging capacities and antioxidant activities. The total phenolics of the extracts was determined spectrophotometrically according to the Folin‐Ciocalteau method using gallic acid as standard solution. The total phenolic compounds were found as 304.5, 367.5, 593, 148.0 and 258.0 mg g‐1 of dry product, respectively. The extracts of SCL, SCR, SCB and SCK were markedly effective in inhibiting the oxidation of linoleic acid and subsequent bleaching of β‐carotene in comparison with the control. Based on oxidation of β‐carotene/linoleic acid, the SCK extract is the most effective followed by SCR, SCL and SCB extract. The antioxidant activity determined by the DPPH (1,1‐diphenyl‐β‐picrylhydrazyl) method revealed that the SCK extract had the highest antioxidant activity on DPPH free radicals followed by SCB, SCR and SCL extracts. The effect of different extracts on the oxidative stability of sunflower oil at 70 °C was tested in the dark and compared with BHA. The oil peroxide values (PVs) were generally lower with the addition of extract in comparison to a control.

Egyptian mango by-product 2: Antioxidant and antimicrobial activities of extract and oil from mango seed kernel

Egyptian mango seeds were collected as wastes from local fruit processing units, the kernels were separated and dried. The antioxidant and antimicrobial activities of mango seed kernel extract and oil were investigated. The results indicated that combination of both mango seed kernel extract and oil had optimum antioxidant potency higher than each one alone. Addition of 400 ppm methanol extract and 5% mango seed kernel oil increased the oxidative stability of sunflower oil incubated at ambient temperature as well as sunflower oil during frying. Moreover, both extract and oil improved the stability and quality characteristics of fresh and stored potato chips. On the other hand, mango seed kernel extract reduced total bacterial count, inhibited coliforms growth, showed remarkable antimicrobial activity against Escherichia coli strain and extended the shelf-life of pasteurized cow milk. These results provide useful information on the utilization of mango seed kernel as natural antioxidant and antimicrobial in foods.

Antioxidant activities of extracts from Combretum hartmannianum and Guiera senegalensis on the oxidative stability of sunflower oil

This study was carried out to investigate the total phenolic compounds beside the potential antioxidant activity of Guiera senegalensis and Combretum hartmannianum extracts. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). The antioxidative activities by beta-carotene linoleic acid and DPPH methods of extracts from Guiera senegalensis leaves, (GSL), Guiera senegalensis roots (GSR) and Combretum hartmannianum leaves (CHL), were evaluated in sunflower oil in the dark at 70°C. Total phenolic compounds were 240.1, 275.6 and 253.4 mg/g respectively. The methanolic extracts of (GSL), (GSR) and (CHL), were markedly effective in inhibiting the oxidation of linoleic acid and subsequent bleaching of s-carotene in comparison with the control. Plants extracts (500 mg) effectively inhibited the formation of peroxides in sunflower oil and showed the highest antioxidative activity compared with 20 mg BHA. The GSL extract is the most effective followed by the GSR and CHL extract. The antioxidant activity of the extracts measured by DPPH free radical showed high reduction of 50% DPPH in CHL extract followed by GSR and GSL. Clear differences were found between the control and sunflower oil containing C. hartmannianum and G. senegalensis extracts or BHA, which decreased and slowed the rate of peroxide formation resulting in lower PVs after 96 h of storage at 70 °C.

Oxidative stability of sunflower oils differing in unsaturation degree during long‐term storage at room temperature

AbstractThe objective of this work was to study the evolution of oxidation in sunflower oils differing in unsaturation degree during long‐term storage at room temperature. For this purpose, a combination of adsorption and size‐exclusion chromatographies was used for quantification of oxidized triacylglycerol (TG) monomers, dimers, and polymers. Conventional sunflower oil, genetically modified high‐oleic sunflower oil, and a 1∶1 mixture of the two were used. Results showed that oxidized TG monomers were the only group of oxidation compounds increasing during the early oxidation stage, and an excellent correlation was found between amounts of oxidized TG monomers and PV during the induction period, independently of the degree of oil unsaturation. Both the rate of formation and the amount of oxidized TG monomers accumulated at the end of the induction period increased as the unsaturation degree of the oils tested was higher. The end of the induction period was marked by the initiation of polymerization and exhaustion of tocopherol. Therefore, the concomitant determination of oxidized TG monomers and polymerization compounds provided a complete picture of the oxidation process.

On‐line LC‐NMR‐MS characterization of sesame oil extracts and assessment of their antioxidant activity

AbstractSesame lignans were isolated by solvent extraction and subsequently purified by solvent crystallization from crude, unroasted sesame oil, and a sesame oil deodorizer distillate. In addition, an aliquot of the purified sesame oil extract was treated with camphorsulfonic acid to obtain a sesaminol‐enriched extract. The sesame lignan composition of the extracts was characterized by on‐line liquid chromatography nuclear magnetic resonance spectroscopy mass spectrometry coupling (LC‐NMR‐MS). The effect of the sesame oil extracts as well as pure sesame lignans and γ‐tocopherol on the oxidative stability of sunflower oil (lignan‐free) was studied by the Rancimat assay. The Rancimat assay revealed the following oxidative stability order: sesame oil extract < sesame oil deodorizer distillate < sunflower oil (no added sesame oil extracts) < sesamol < sesaminol‐enriched sesame oil extract. In addition, the radical‐scavenging capacity of these extracts was assessed by the Trolox® equivalent antioxidant capacity (TEAC) assay. The TEAC assay revealed a slightly different AOX activity order: sesamin < sesame oil extract < sesaminol‐enriched sesame oil extract < sesamol. In conclusion, the sesaminol‐enriched extract revealed strong antioxidant activity and is therefore suitable to increase the oxidative stability of edible oils high in polyunsaturated fatty acids.

Identification and genetic characterization of new sources of beta- and gamma-tocopherol in sunflower germplasm

SUMMARY Sunflower seeds have more than 90% of the total tocopherols in the form of alpha-tocopherol, which exerts a weak antioxidant protection of the extracted oil. A partial substitution of alpha-tocopherol by another tocopherol derivative with greater antioxidant action would improve the oxidative stability of sunflower oil. The objective of the present research was to identify sources of modified tocopherol profile in sunflower germplasm. A total of 952 germplasm accessions were evaluated by analyzing the tocopherol profile of 12 half-seeds per accession by HPLC. The screening resulted in the identification of a source of increased beta-tocopherol content and a source of increased gamma-tocopherol content. In both cases the accessions corresponded to old populations of Peredovick. The line T589 presented a beta-tocopherol content from 30.4 to 48.5% of the total tocopherols, whereas the line T2100 had a gamma-tocopherol content from 87.9 to 93.9%. Genetic studies revealed that both traits were partially recessive in crosses with material with standard tocopherol profile. In both lines, the altered trait was determined by alleles at a single locus. Comparative studies with previously developed sunflower lines with similar levels of beta- and gamma-tocopherol will elucidate whether the new lines have the same or different genetic modifications within the tocopherol biosynthetic pathway.

Effect of plant extracts on the oxidative stability of sunflower oil and emulsion

The antioxidative activities of six plant extracts (catnip, hyssop, lemon balm, oregano, sage and thyme) were evaluated in sunflower oil and its 20% oil-in-water emulsion in the dark at 60°C. The oxidation process was followed by measuring the formation of primary (conjugated diene hydroperoxides) and secondary (volatile compounds) oxidation products. Sage extracts (600 and 1200 ppm) effectively inhibited the formation of conjugated dienes and volatile compounds (hexanal and pentanal) in oil and emulsion and showed the highest antioxidative activity compared with 300 ppm BHT. Thyme and lemon balm extracts inhibited hexanal generation more than formation of conjugated dienes in both oil and emulsion. Oregano extract was more active in oil than in emulsion. Catnip and hyssop extracts (600 ppm) showed prooxidative action to sunflower oil at 60°C. These two extracts increased the formation of conjugated dienes compared with the control oil. In emulsions, catnip extract (600 ppm) was active and significantly inhibited the formation of conjugated dienes more than BHT (300 ppm) during additional incubation.

Effect of an Ethanol Extract from Summer Savory (Saturejae hortensisL) on the Stability of Sunflower Oil at Frying Temperature

The effect of the ethanol extract from Saturejae hortensis L on the oxidative and thermal processes occurring in sunflower oil during its high-temperature treatment (180°C) was investigated. The changes during simulated deep fat frying were monitored by determination of the oxidation stability at 100°C, as well as by determination of unchanged triacylglycerols. It was established that the addition of 1 and 5 g kg-1 ethanol extract from S hortensis L leads to a decrease in the oxidative and thermal changes in the oil. The ethanol extract from S hortensis L improved the oxidative stability of sunflower oil even after 50 h at 180°C and it inhibited the oxidative processes more than the thermal processes under these conditions. © 1997 SCI.

Genetic variability of tocopherol composition in sunflower seeds as a basis of breeding for improved oil quality

AbstractThe variability of seed tocopherol content in wild sunflower species, the expressivity of tph1 and tph2 mutations in different lines and the oxidative stability of sunflower oil with altered tocopherol and fatty acid composition were objectives of this research.Near‐isogenic lines for three genes, i.e. Tph1, Tph2, and Ol, were developed and investigated. Tocopherol content was determined with TLC and HPLC, as well as fatty acid composition with GC of methyl esters. Rancimat tests were used to estimate the oxidative stability of the oil.The seed tocopherol composition of wild sunflower species was shown to be uniform with a prevailing content of the α‐homologue (90‐99%). The genetic background of different near‐isogenic lines was found to influence expressivity of mutations for tocopherol composition. High content of strong antioxidants, such as β‐, γ‐, and δ‐tocopherols increased oil oxidative stability of linoleic and oleic types of oil by 1.2–3.0 times.The breeding model of sunflower hybrids should include antioxidant and vitamin parameters balanced for oils of different applications.

Improved oxidative stability of sunflower oil in the presence of an oxygen‐scavenging film

AbstractThe oxidative stability of sunflower oil (SFO) was measured during storage at 23 and 37°C in the presence of a novel oxygen‐scavenging film that contained polyfuryloxirane (PFO). Commercially refined and deodorized SFO was stored in a lighted room in sealed transparent packages containing either PFO film or an antioxidant, 0.02% butylated hydroxytoluene (BHT). Oxidative stability was evaluated by determination of peroxide values and gas‐chromatographic measurement of headspace hexanal. SFO stored in the presence of the oxygen‐scavenging film was more stable than oil stored without the film, or than film stored with 0.02% BHT. The PFO film scavenges oxygen through energy‐transfer sensitization of singlet oxygen. The film is doped with eosin and the naturally‐occurring dye, curcumin, which absorb over a wide range of visible wavelengths. Curcumin transfers its absorbed energy to eosin, which sensitizes the production of singlet oxygen. The singlet oxygen is scavenged by PFO. The use of two dyes increases the efficiency of the sensitization process, reducing the illumination time and intensity required for effective oxygen scavenging.

Oxidative stability of sunflower oil extracted with supercritical carbon dioxide

AbstractExtraction of oilseeds with supercritical carbon dioxide (SC−CO2) is a promising technique to obtain vegetable oils. However, instability of such oils has been associated in the past with SC−CO2 extraction. The reasons underlying such instability were unclear. Results presented here suggest that oil instability may be related to the oxygen content of CO2. In fact, oil stability decreases sharply when refined oil (additive‐free) is re‐extracted with SC−CO2 and can be related to the oxygen content in the CO2. Never‐theless, oil stability could be improved to the level of conventionally extracted oil by adding trace amounts of ascorbic acid.

Utilization of sunflower seeds in tahina and halawa processing

Sunflower seeds were cleaned, roasted, decorticated and ground to a smooth thick oily suspension (tahina). Chemical analysis showed that sunflower tahina-like butter contained higher ether extract (62·3%) than sesame tahina (55·3%). Sesame tahina was higher in ash and carbohydrate contents, while the protein content was similar in both. Microscopic examination of stained films indicated that the system in sunflower tahina was essentially a suspension of solid particles in a continuous oil phase (water in oil system). Oil separation in sunflower tahina was followed during storage at room temperature for 90 days. The addition of glycerol monostearate had a pronounced stabilizing action resulting in reducing oil separation from 11·8% to 6·25%. The peroxide value of sunflower tahina oil increased during storage, reaching a maximum value after 60 days' storage, then decreased. The oxidative stability of sunflower oil was increased with the addition of 0·02% butylated hydroxy anisole (BHA) and 0·02% butylated hydroxy toluene (BHT). Organoleptic evaluation showed no significant differences between sunflower and sesame halawas in texture and flavor except that the color of sunflower halawa was distinctly darker. The chemical analysis emphasized the high caloric, as well as nutritive value, of sunflower halawa. The use of Egyptian sunflower seeds in tahina and halawa tahiniamaking would reduce the importation of sesame seeds.