Influence of fried and fried‐treated oils with different filter aids on rat health

Soybean, sunflower, palm and cottonseed oils were fried continuously at 180 ± 5 °C for 12 h. Fried oil quality was regenerated by adding individually Magnesol XL, diatomaceous earth and kaolin at 2% level, then stirring mechanically at 105 °C for 15 min and filtering. A set of nutritional experiments was conducted in which rats were administered standard diets containing non‐fried, fried and fried‐treated oils with various filter aids. The safety limits of the fried‐treated oils were recognized by measuring the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (AP), and levels of total lipids, total cholesterol, HDL cholesterol and LDL cholesterol of rat sera. Also, histopathological evaluation of rat liver tissues was microscopically done to detect any damage that might occur due to feeding rats on non‐fried, fried and fried‐treated oils. Administration of fried oils to rats induced significant rises in activities of ALT, AST and AP, and increases in the levels of total lipids and total cholesterol. The results demonstrate that there were non‐significant changes in sera levels of LDL and HDL cholesterol in rats fed diets containing various types of soybean, sunflower and cottonseed oils. Administration of fried‐treated oils to rat diets indicates that the activities of ALT, AST and AP and levels of sera constituents were similar to those of rats given non‐fried oils. Palm oil exceptionally behaved differently from the other oils. Palm oil raised sera total cholesterol and LDL cholesterol and lowered HDL cholesterol level. Histopathological examination of rat liver tissues indicated that changes paralleled the biochemical data. Copyright © 2006 Society of Chemical Industry     

Use of some agricultural waste hull ashes for the regeneration of fried sunflower oil

The present study was aimed at improving the quality of fried sunflower oil. Synthetic (Magnesol XL), natural (diatomaceous earth) and hull ashes of rice, wheat and barley (agriculture plant wastes) were used to adsorb the oxidation products of fried sunflower oil. The mineral pattern (Si, Mg, Ca, Fe, Al, Mn and Cu) of the aforementioned substances were determined. The physico-chemical properties [refractive index, viscosity, colour, smoke point, acid value, peroxide value, thiobarbituric acid (TBA) value, conjugated dienes and trienes, polar content, polymer content and oxidised fatty acids] of non-fried, fried and fried-treated sunflower oil were determined. The frying process was carried out at 180 °C ± 5 °C for 20 h, 4 h heating cycle per day for five consecutive days. The fried sunflower oil was treated with synthetic, natural and agricultural hull ashes at 105 °C for 15 min. The results indicate that Magnesol XL, diatomaceous earth, rice hull ash, wheat hull ash and barley hull ash contained Si + Mg + Mn, Si + Mn + Ca, Si + Mn, Si +Mn and Mn + Si as the basic metals, respectively. Frying of sunflower oil led to significant increase in refractive index, viscosity, colour, smoke point, acid value, peroxide value, TBA value, conjugated dienes and trienes, polar content, polymer content, and oxidised fatty acids and decrease in iodine value. Treatments of fried sunflower oil with the aforementioned substances greatly improved the quality of fried oil. Under the present experimental conditions all adsorbing substances performed similarly in removing the fried sunflower oil oxidation products.     

Evaluation of the bellier test in the detection of olive oil adulteration with vegetable oils

Virgin olive oil was mixed with eight vegetable oils (sunflower, soya bean, palm, linseed, cottonseed, corn, sesame, and olive residue) at various levels. The Bellier test was applied to find the minimum detectable adulteration level and the ‘sensitivity score’ for each oil. The test was inapplicable to sunflower and linseed oils regardless of the level in olive oil. It was successful in detecting olive residue, soya bean, palm, cottonseed, corn, and sesame oils at minimal levels of 730, 150, 130, 90, 60 and 10 g kg^?1, respectively. The rancidity level of the adulterant oils did not affect the performance of the test in the case of sunflower, linseed and sesame oils. The sensitivity of the test decreased considerably with increasing peroxide value of the adulterant oil: soya bean, palm, cottonseed, corn and olive residue. However, the change in sensitivity level commenced at so high a peroxide value that it has no significance for practical purposes; at such levels of peroxidation the adulterated olive would be unmarketable and rejected by inspectors due to its poor sensory quality.     

Extra-Virgin Olive Oil and Cheap Vegetable Oils: Distinction and Detection of Adulteration as Determined by GC and Chemometrics

Refined oils including corn, sunflower, soybean, and palm oils as well as low-quality olive oil such as refined lampante and pomace olive oils are commonly used for extra-virgin olive oil (EVOO) adulteration. Indeed, K ₂₇₀ could be used as a parameter for the detection of EVOO fraud for each type of the studied refined oils, 10 % olive, 4 % pomace olive, 10 % palm, 5 % corn, and 2 % soybean oils. Moreover, the adulteration could also be detected by the increase of the trans fatty acid contents with 10 % pomace olive, 3 % soybean, 3 % sunflower, 2 % corn, and 10 % palm oils. Actually, stigmasta-3,5-diene content is one of the most effective means of detecting refined oils in EVOO at low levels: 2 % olive, 0.4 % pomace olive, 1 % palm, 0.2 % soybean, 0.5 % sunflower, and 0.1 % corn oils. Finally, the application of linear discriminant analysis could represent an alternative and innovative tool for faster and cheaper evaluation of EVOO adulteration.     

Distribution and retention of phytosterols in frying oils and fried potatoes during repeated deep and pan frying

The retention and distribution of phytosterols in fried oils and French-fries during eight successive pan- and deep-frying sessions of pre-fried potatoes in sunflower oil, palm oil, cottonseed oil, virgin olive oil and a vegetable shortening were evaluated. Phytosterols (β-sitosterol, campesterol, stigmasterol, Δ⁵-avenasterol) were determined in the unsaponifiable fraction of frying oils and lipids extracted from French-fries by GC/FID after derivatization to trimethylsilyl ethers. French-fries were enriched with phytosterols due to the absorption of frying oil, with β-sitosterol predominating in both fried oils and potatoes. The amount of phytosterols decreased during frying, their overall retentions reaching 9.5–22.8% and 29.4–51.2% after eight successive pan- and deep-frying sessions, respectively, while their deterioration was found to be affected by frying time, frying technique, being more prolonged during pan-frying, and by the oils’ unsaturation, being more extended in polyunsaturated oils. Phytosterols were more or less uniformly distributed between the fried oil and the fried potatoes. The phytosterols dietary intake by consuming potatoes fried in the oils tested is discussed.     

Rheological characteristics of vegetable oils as affected by deep frying of French fries

Fatty acid composition and rheological characteristics of sunflower oil (SO), cottonseed oil (CO) and palm olein (PO) during deep frying for 4–16 h were investigated. In the different oils, linoleic acid decreased while palmitic, stearic and oleic acids increased in the bath oil during frying. Total phenolic content (TPC) in different oils increased during frying and strongly correlated with frying time. As frying progressed, it was observed that the rate of increase in TPC was relatively slower in PO than in the SO and CO. The shear stress versus shear rate results was fitted to Newtonian, Bingham and Herschel–Bulkley rheological models. The flow behaviour of fresh and fried SO, CO and PO was recorded at 25 °C. Fresh oils showed Newtonian behaviour with correlation coefficients greater than 0.99 at 25 °C and slight non-Newtonian behaviour after frying. Palm olein showed higher increase in viscosity in comparison to CO and SO. Rheological parameters of vegetables oils showed great changes, wherein the highest change in viscosity was recorded after 16 h of frying. Palm olein had higher flow behavior parameters than SO and CO. The increase in frying time caused an increase in K, η_B, τ_0HB, τ_0B, and η values, while the n values decreased with increasing the frying time. The viscosities of oils were plotted against the levels of C18:1 and C18:2 wherein highly positive correlations were found between them (R² = 0.99). The temperature dependence of viscosity was studied by using the Arrhenius relationship and the activation energy indicates the sensitivity of viscosity to changes in temperature. It could be concluded that the rheological parameters can provide an overall estimate of oil quality during frying.     

Loss of tocopherols and formation of degradation compounds at frying temperatures in oils differing in degree of unsaturation and natural antioxidant content

Samples of oils of different degrees of unsaturation, namely palm olein, olive oil, high‐linoleic sunflower oil, high‐oleic sunflower oil, rapeseed oil and soybean oil, were heated at 180 °C for 2, 4, 6, 8 and 10 h in the presence or absence of their natural antioxidants. Also, tocopherol‐stripped oils were supplemented with α‐tocopherol (500 mg kg^?1), δ‐tocopherol (500 mg kg^?1) or a mixture of α‐, β‐, γ‐ and δ‐tocopherols (250 mg kg^?1 each) and heated under the same conditions. Losses of tocopherols and formation of polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10 h of heating. Results demonstrated that tocopherols were lost very rapidly, in the expected order, with α‐tocopherol being the least stable. Polymeric and polar compound formation during heating was inhibited to a variable extent, being more dependent on the natural content and type of tocopherols than on the degree of unsaturation of the oil. For example, polymeric and polar compound contents in soybean oil were significantly lower than those found in high‐linoleic sunflower oil. However, the expected influence of the degree of unsaturation was evident when oils were unprotected or possessed identical initial antioxidant contents. Finally, levels of degradation compounds after 10 h of heating were not dependent on the remaining content of antioxidants. © 2002 Society of Chemical Industry     

Lipid oxidation-related characteristics of gim bugak (Korean fried cuisine with <Emphasis Type="Italic">Porphyra</Emphasis>) affected by frying oil

The effect of frying oil on the lipid oxidation, antioxidants, and in vitro antioxidant activity of gim bugak was studied. Bugak was prepared by pan-frying at 180 °C in unroasted sesame, soybean, extra virgin olive, or palm oil. The degree of lipid oxidation based on conjugated dienoic acid and p-anisidine values was higher in the bugak fried in soybean or sesame oil with high contents of polyunsaturated fatty acids and tocopherols. However, the oil oxidation was lower in olive and palm oils, which showed higher degradation of tocopherols and polyphenols than in sesame or soybean oil during frying. Although the bugak fried in palm oil contained less antioxidants than that fried in soybean or sesame oil, the in vitro antioxidant activity was not different (p > 0.05). Results suggest that palm oil can replace unroasted sesame oil for the preparation of gim bugak with improved lipid oxidative stability and health functionality.     

Aflatoxins in sunflower seeds and unrefined sunflower oils from Singida,Tanzania

A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B₁ ranging from limit of detection (LOD) to 218 ng g^?1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g^?1 for AFB₁ in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g^?1. Other aflatoxins, except AFG₂, were also detected. For the unrefined sunflower oils, the levels of AFB₁ ranged from LOD to 2.56 ng mL^?1. About 80.9% (17/21) of the analysed oil samples contained AFB₁ of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL^?1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.     

Quality characteristics of refined,bleached and deodorized palm olein and banana chips after deep‐fat frying

The changes in quality characteristics of refined, bleached and deodorized (RBD) palm olein used for deep‐fat frying of banana chips (180°C for 3 min at 17 min intervals for 2 h day^?1, to give six fryings per day and 30 fryings over five consecutive days) were studied. Four frying systems were used: RBD palm olein without antioxidant (system 1); RBD palm olein with 0.2 g kg^?1 α‐tocopherol (system 2); RBD palm olein with 1 g kg^?1 oleoresin rosemary (system 3); and RBD palm olein with the combination of 0.1 g kg^?1 α‐tocopherol + 0.5 g kg^?1 oleoresin rosemary (system 4). Fried oil samples were analysed for fatty acid composition, peroxide value (PV), anisidine value (AnV), totox value, free fatty acids (FFA) value, iodine value, at 232 and 268 nm, colour and viscosity. The crispness and sensory evaluation of the banana chips fried in this study were also evaluated. The results showed that RBD palm olein with added antioxidant reduced PV, AnV, totox value, at 232 and 268 nm, FFA and viscosity. The order of effectiveness in inhibiting oil oxidation in RBD palm olein was: oleoresin rosemary > α tocopherol + oleoresin rosemary > α‐tocopherol > control. For the crispness, the force values of banana chips fried in all systems were comparable. Sensory evaluation of fried banana chips for each system showed that there was no significant (P > 0.05) difference in terms of colour, flavour, odour, texture and overall acceptability. Copyright © 2003 Society of Chemical Industry     

Monitoring of Zn(II), Cd(II), Pb(II) and Cu(II) During Refining of Some Vegetable Oils Using Differential Pulse Anodic Stripping Voltammetry

In this study, a novel approach has been developed using differential pulse anodic stripping voltammetry (DPASV) for the simultaneous determination of Zn(II), Cd(II), Pb(II) and Cu(II) in edible oils at hanging mercury drop electrode. The microwave digestion of oil samples was carried out with concentrated HNO₃ and H₂O₂. KNO₃ was used as a supporting electrolyte. The experimental conditions optimized such as deposition time, stirring rate and size of mercury drop were 300 s, 600 rpm and 10 mm², respectively. The method was applied to quantify Zn(II), Cd(II), Pb(II) and Cu(II) in crude and refined hazelnut, corn, sunflower and olive oils. During refining of different vegetable oils, the removal efficiencies of Zn(II), Cd(II), Pb(II) and Cu(II) were calculated as 98.20–99.91, 98.50–99.90, 95.26–99.76 and 95.93–99.92 %, respectively. The limits of detection for Zn(II), Cd(II), Pb(II) and Cu(II) were 2.1?×?10^?8, 8.7?×?10^?10, 7.1?×?10^?9 and 3.4?×?10^?9 and the limits of quantification were 6.8?×?10^?8, 2.9?×?10^?9, 2.3?×?10^?8 and 1.1?×?10^?8 M with linear regression coefficients (R ²) of 0.9930, 0.9928, 0.9893 and 0.9931, respectively. It was observed that the above metals in crude and refined vegetable oils could be determined simultaneously by the DPASV method.     

Quantitative determination of the iodine values of unsaturated plant oils using infrared and Raman spectroscopy methods

Thirteen edible oils: sunflower, avocado, hemp, high-linolenic flax, low-linolenic flax, safflower, walnut, roasted sesame, rice, corn, rapeseed, pumpkin seed, and hazel were studied in this work. Their fatty acid composition, iodine, acidic, peroxide, and saponification values were determined. Infrared and Raman spectra of the oils were recorded in the range 400–3200 cm^?1. The integral intensities of the bands at about 1655 and 2852 cm^?1 corresponding to ν(C=C) and ν(CH₂) vibrations were evaluated and used to construct a relationship between the spectroscopic data and the iodine value. The following linear dependencies were obtained: I_ν(C=C)/I_ν(CH2) = 7.449 × 10^?4 × iodine value – 0.0339 and I_ν(C=C)/I_ν(CH2) = 9.299 × 10^?4 × iodine value – 0.023 for the infrared and Raman spectra with a correlation coefficient 0.988 and 0.976, respectively. These calibration lines can be used to determine the iodine value for oils with unknown unsaturation level, and may be applied for margarines and other fatty materials.     

The tocopherol content of greek olive oils

Four types of Greek olive oil were analysed for α-and γ-tocopherols by high performance liquid chromatography. Certain seed oils widely consumed in Greece were also analysed for comparison with the olive oils. Virgin, pure, residual and refined oils contained an average of 113,81,156 and 37 mg kg^?1 of α-tocopherol, respectively. The α-tocopherol level within each type of olive oil appeared to be influenced by different factors. The content of y-tocopherol averaged 17 and 33 mg kg^?1of virgin and residual oil, respectively. Refined and pure olive oil contained very low levels of y-tocopherol. The α-tocopherol equivalent per gram of polyunsaturated fatty acids was calculated to be 1·48, 0·60, 0·88, 1·07 and 0·58 for edible olive oils, corn, cottonseed, sunflower and partially hydrogenated soya bean oil, respectively.     

Flavor and Storage Stability of Potato Chips Fried in Cottonseed and Sunflower Oils and Palm Olein/Sunflower Oil Blends

ABSTRACT: Potato chips fried in cottonseed (CSO) and sunflower (SFO) oils and 20 and 40% palm olein oil (POO):SFO blends were stored at 23 to 25 °C for 0-, 3- and 6-wk in dark (DS) and in 1.5-1.7 footcandles of light (LS). During DS, peroxide values (PV) increased only in chips fried in SFO. In LS, PV increased at lower rates in chips fried in POO blends than in CSO or SFO. Sensory evaluation showed potato chip flavor intensity was similar among oils/blends and unchanged during storage, but intensities of oxidative rancidity and off-flavor increased in chips fried in CSO at 6-wk LS. This off-flavor most likely was due to 1-decyne identified by SPME analysis. Addition of POO to SFO improved the stability of chips as measured by PV without sacrificing potato chip flavor.     

Temperature dependence of the autoxidation and antioxidants of soybean, sunflower, and olive oil

Effects of temperature on the autoxidation and antioxidants changes of soybean, sunflower, and olive oils were studied. The oils were oxidized in the dark at 25, 40, 60, and 80 °C. The oil oxidation was determined by peroxide (POV) and p-anisidine values (PAV). Polyphenols and tocopherols in the oils were also monitored. The oxidation of oils increased with the oxidation time and temperature. Induction period decreased with the oxidation temperature; 87 and 3.6 days at 25 and 60 °C, respectively, for sunflower oil. The activation energies for the autoxidation of soybean, sunflower, and olive oils were 17.6, 19.0, and 12.5 kcal/mol, respectively. Olive oil contained polyphenols at 180.8 ppm, and tocopherols were present at 687, 290, and 104 ppm in soybean, sunflower, and olive oils, respectively. Antioxidants were degraded during the oil autoxidation and the degradation rates increased with the oxidation temperature of oils; for tocopherols, 2.1 × 10⁻³ and 8.9 × 10⁻²%/day at 25 and 60 °C, respectively, in soybean oil.     

基于GC-IMS分析三种植物油炒制海鲈鱼鱼松中挥发性风味物质的研究

本研究以海鲈鱼鱼松为研究对象,通过感官评分、色差和质构确定了植物油最佳添加量为3%。在此基础上,采用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectroscopy,GC-IMS）技术深入分析了三种植物油（花生油、棕榈油和葵花籽油）炒制鱼松过程中挥发性风味物质的组成情况。结果表明,三种植物油炒制的鱼松中共鉴定出40种挥发性风味物质,包括醛类、醇类、酯类和酮类化合物等,其中,花生油、棕榈油和葵花籽油炒制鱼松中醛类的相对含量最高,分别为63.33%、57.58%和43.75%。不同植物油炒制鱼松中存在特征风味物质,其中,丙醛、苯甲醛分别只存在于花生油、棕榈油炒制鱼松中;3-甲基-1-丁醇和己醛同时存在于花生油和葵花籽油炒制鱼松中。本研究结果表明根据GC-IMS建立的三种植物油炒制鱼松指纹图谱相似度较低,能有效区分炒制鱼松的植物油来源,可作为植物油炒制鱼松的鉴定及掺伪鉴别的有效手段。     

Relative Oxidative Stability of Diacylglycerol and Triacylglycerol Oils

To compare the oxidative stability between diacylglycerol (DAG) oil and conventional triacylglycerol (TAG) oil (that is, soybean oil), the prepared stripped diacylglycerol oil (SDO) and soybean oil (SSBO) were stored at 60 °C in the dark for 144 h. During storage peroxide values (POVs), contents of aldehydes, unsaturated fatty acids were measured to evaluate the oxidative stabilities of the 2 oils. The results showed the content of C18:2, C18:3, and total unsaturated fatty acid decreased faster in DAG oil than in soybean oil, whereas the decreased rate of C18:1 was similar in 2 oils. Also, both rate constants (K₁ and K₂) obtained from POV (K₁) and total aldehydes (K₂) indicated that DAG oil (K₁ = 3.22 mmol/mol FA h^?1, K₂ = 0.023 h^?1) was oxidized more rapidly than soybean oil (K₁ = 2.56 mmol/mol FA h^?1, K₂ = 0.021 h^?1), which was mainly due to the difference of acylglycerol composition of the 2 oils along with higher C18:3 (9.6%) in SDO than SSBO (5.7%). It is concluded that DAG was more easily oxidized than soybean oil at 60 °C in the dark for 144 h.     

Carbonaceous materials from seed hulls for bleaching of vegetable oils

Seed hulls, namely cottonseed, peanut, sunflower, soybean, faba bean and lupine were evaluated as carbonaceous materials for the bleaching of crude soybean oil. The six seed hulls were activated by carbonization, steam activation and acid activation. Two reference standards, Fullers earth and Tonsil clay, were used for comparison throughout the whole study. Bleaching of crude soybean oil under vacuum at 100 °C using the treated hulls was carried out. The effect of bleaching with the different hulls on the oil characteristics was evaluated by determining the % free fatty acid, % reduction in peroxide value, % removal of phospholipids, % bleachability and oxidative stability of the bleached oils. Results revealed that bleaching with carbonized hull yielded oils with least free fatty acid content and highest oxidative stability. Bleaching with acid activated hull carbons gave oils with least content of peroxides, phospholipids together with best color. Acid activation of the hulls resulted in highest increase in surface area, pore volume and least pore dimension.     

Evaluation of shortenings based on various palm oil products

Several formulations based on blends of hydrogenated palm oil (MP 41·5°C) and palm stearin (IV 44) with other liquid oils, on direct blends of palm stearin with other liquid oils, and on 100% inter-esterified palm olein, were used as feedstocks in shortening production. The shortenings were stored at 20°C over a period of one month. Physicochemical characteristics, creaming properties and baking performance of the shortenings were evaluated and compared with the best shortening on the market. Slip melting point of the shortenings ranged from 41·5 to 46·4°C. Palm-cottonseed oil shortenings had higher solid fat contents at all temperatures than palm-soya bean or palm-low erucic acid rapeseed oil shortenings. The shortenings were rich in C₅₀, C₅₂and C₅₄ glycerides. Creaming power after 12 min of beating ranged from 1·55 to 1·77 cm³ g^?1. Palm stearin-cottonseed (3:2) oil shortening showed the best creaming performance. The specific volume of cakes ranged, for the experimental shortening, from 90% to 101% from the control, with low erucic acid-palm blends showing the best performance. In applications for both aerated cream and cakes, inter-esterified palm olein was excellent.