Novel Two-Phase Catalysis with Organometallic Compounds for Epoxidation of Vegetable Oils by Hydrogen Peroxide

A series of new organometallic catalysts for epoxidized vegetable oils using H₂O₂ in a biphasic system were investigated. The effect of reaction parameters such as the amount of hydrogen peroxide, reaction time and temperature in the epoxidation of soybean oil are discussed in detail. A selectivity of 83.8% was obtained in 4 h at 60 °C, when [(C₁₈H₃₇)₂N(CH₃)₂]₃{PO₄[WO(O₂)₂]₄} was used as the catalyst. When methyltrioxorhenium (MTO), imidazole and CH₃CN were used as the catalyst, adduct, and solvent respectively, a selectivity of 99.90% was achieved in 4 h at 20 °C. The catalytic system was used for the epoxidation of other oils, whose results showed it was active in the epoxidation of long-chain unsaturated compounds. Furthermore, the reaction of H₂O₂ with methyltrioxorhenium was studied by UV–Vis spectroscopy, which revealed the active peroxorhenium complexes formed during the reaction. Epoxidation of these oils with organometallic compounds occurred through the interactions between the oils unsaturated sites HOMO π(C–C) and the unoccupied peroxo σ*(O–O) orbital.     

Revisiting the Enzymatic Epoxidation of Vegetable Oils by Perfatty Acid: Perbutyric Acid Effect on the Oil with Low Acid Value

Enzymatic epoxidation of vegetable oils in the presence of free fatty acids has been well studied in recent years, by mainly using long chain fatty acids (e.g., stearic acid) as the active oxygen carrier. However, for the previous enzymatic processes, the acid value (AV) of final epoxidized oils using long chain fatty acids is high, and the free fatty acid is not easily removed in the post treatment with water. Aiming at developing a more sustainable process, enzymatic epoxidation of sunflower oil was revisited using different free fatty acids catalyzed by Novozym 435 (lipase B from Candida antarctica, provided by Novozymes, Bagsvaerd, Denmark). When long chain stearic acid was introduced into the epoxidation in toluene solvent, the epoxy oxygen group content (EOC) of 6.41 ± 0.19 % was obtained. Due to the poor water solubility of stearic acid, the AV of the final epoxidized oil product was very high (53.40 ± 1.34) after it was washed with water. Alternatively, current study shows that the epoxidation process using short chain butyric acid produced the final epoxidized oil with lower AV of 2.57 ± 0.11. When the enzymatic epoxidation of sunflower oil was optimized in the presence of butyric acid and Novozym 435, EOC of 6.84 ± 0.21 % was obtained, reaching an oxriane conversion of 96.4 ± 3.0 %. Therefore, introducing short chain butyric acid as an active oxygen carrier will provide an alternative to the present enzymatic epoxidation process and produce the desired epoxidized oil products with much lower AV only after simple water‐treatments, which will make the enzymatic epoxidation more attractive.     

Comparative Fingerprint Changes of Toxic Volatiles in Low PUFA Vegetable Oils Under Deep-Frying

The volatile fraction of three vegetable oils recommended for deep‐frying due to their high MUFA:PUFA ratios, namely extra‐virgin olive oil, peanut oil and canola oil, was compared before and after frying potatoes, with a particular focus on toxic volatiles. For the purpose, a headspace solid‐phase‐micro extraction technique coupled with gas chromatography and mass spectrometry was optimized, with semi‐quantification achieved using two internal standards. Significant qualitative and quantitative differences were observed, both before and after frying. From a total of 51 compounds, aldehydes were the main group formed after deep‐frying, their nature and abundance being highly associated with the initial fatty acid composition, particularly linoleic acid (r² = ?0.999, p ≤ 0.001). Globally, extra‐virgin olive oil revealed fewer formations of unsaturated aldehydes, including toxic ones, and correlated with lower amounts of degradation indicators, as polar compounds (r² = 0.998, p ≤ 0.001) and p‐anisidine value (r² = 0.991, p ≤ 0.001). Despite the similarities in total unsaturation degree between canola and peanut oils, the former presented lower amount of volatiles, including E,E‐2,4‐decadienal and acrolein, the more toxic ones. These results highlight for the pertinence of volatile analyses to evaluate and compare oil degradation under thermal and oxidative stress, while complementing other degradation indicators. Additionally, the optimized methodology allows a direct comparison of different oil matrices, supporting further developments into more general methods for volatiles quantification, enabling more efficient comparison of results between research teams.     

A Comparative Study of the Properties of Selected Melon Seed Oils as Potential Candidates for Development into Commercial Edible Vegetable Oils

A comprehensive compositional and characterization study was carried out on five seed oils from varieties of the melons Citrullus lanatus and C. colocynth in order to evaluate their suitability for large-scale exploitation as edible vegetable oils. The oils were extracted by Soxhlet with a 3:1 mixture of n-hexane/2-propanol with yields that ranged from 24.8 to 30.0% (wt/wt). The refractive indices and relative densities of the oils fell within the narrow ranges of 1.465–1.469 and 0.874–0.954 g/cm³, respectively. Saponification values ranged between 182.1 and 193.8 mg KOH/g, whilst iodine values (IV) ranged from 95.8 to 124.0 (Wijs). The ranges of the values for free fatty acid (AV), 1.2–4.0 mg KOH/g, peroxide (PV), 1.1–10.9 meq/kg and p-anisidine (p-AV), 0.2–9.0, indicated that secondary oxidation products were barely present. GC analysis gave total unsaturation contents of 67.93–82.36%, with linoleic acid (18:2) being the dominant fatty acid (55.21–66.85%). The GC results agreed closely with those from proton NMR analysis of the fatty acid classes. The physicochemical and compositional properties determined in this study show that the qualities of the test Cucurbitacea seed oils are highly comparable to those of soybean, sunflower and groundnut seed oils. Therefore, the test melon seed oils could be developed into commercial products to serve as alternate vegetable oils in Southern and West Africa, the regions where these melons grow.     

Kinetics of Bleaching of Vegetable Oils

It was shown in a recent paper that the concentration c of remaining chlorophyll or carotene in rapeseed oil during the bleaching process follows a rate formula, log c/c_o =– k √t, characteristic of flocculation of colloids. Thus, the pigments are particulate and colloidally dispersed in the oil. The rate constant k was proportional to the added amount of clay. This paper reports experiments with palm oil. The same kinetics as those with rapeseed are valid. The effects of various parameters on the rate have been studied. The mechanism of the process is discussed. Presented at the AOCS meeting, New Orleans, May 1981.     

Velocity of Sound in Vegetable Oils

The velocity of sound in seven vegetable oils has been measured to an accuracy of ± 0.3 ms^?1. The different values of the velocities are correlated on the basis of composition. Average values for the temperature coefficient of velocity, at room temperature, and for the dispersion between 2 and 10 MHz are also given.     

Solvent Interesterification of Vegetable Oils III

Directed interesterification reaction in solvents of cottonseed, peanut and cottonseed containing peanut, sesame and safflower oils was investigated with special reference to the influence of amount of sodium methoxide catalyst, oil content in solvent, temperature during the reaction and the nature of solvent on the characteristics of the reaction. The parameters were first studied with cottonseed oil and the conditions that favoured the reaction were adopted for peanut oil and cottonseed oil mixtures.     

Effects of Vegetable Oil Composition on Epoxidation Kinetics and Physical Properties

In this article, we investigate the role of triacylglycerol composition on the properties of epoxidized vegetable oils and the kinetics of the epoxidation process under conditions comparable to commercial epoxidation. Commodity soybean oil (24% oleic acid, 50% linoleic acid, and 7% linolenic acid), high‐oleic soybean oil (75% oleic acid, 8% linoleic acid, and 2.5% linolenic acid), and linseed oil (11% oleic acid, 15% linoleic acid, and 64% linolenic acid) were each epoxidized to various extents. Epoxidation rate, viscosity, differential calorimetry, and X‐ray diffraction data are presented for these oils and interpreted in the context of their fatty acid profile (mostly oleic, linoleic, or linolenic). While fully epoxidized soybean oil is widely commercially available and used in an increasing array of industrial applications, information relating to partially epoxidized oils and epoxidized oils of other cultivars is less well known.     

Chromatographic Detection of Silicones in Vegetable Oils

The method is based upon separation of silicone in the oil by thin layer Chromatography on silica gel layer, using the solvent system petroleum, ether—diethyl ether = 98:2 (v/v) and visualisation of the spots developed by means of Rhodamin B reagent. Under the described condition separation of silicones seems to be free from interference from other non-silicone containing materials. The limit of detection was approximately 2 γ.     

On the Fatty Acid Composition of Turkish Vegetable Oils

Because of the variety of climate conditions very different oil plants except of some tropical kinds grow in Turkey. In this work four groups of raw material of Turkish vegetable oils were investigated. The first group consists of olive, sunflower and cotton, which are important raw materials in Turkey. About 97% of the oil produced in Turkey base on these three raw materials. The second group consists of sesame, poppy, linseed, hemp-seed, rape, soyabean, safflower, castor bean and groundnut, which are temporary of lower importance for Turkey. The third group consists of the non-traditional oil raw materials like tobacco seed, grape seed, scabious, fig seed, tomato seed, laurel seed, pistacia terebinthus, rice bran, maize germs, anise seed, peach-stones and pumpkin seed. The fourth group consists of fruits rich in oil like hazel-nuts, walnuts, almonds and pistachio-nuts, whose production is of great importance in Turkey.     

New UV-Curable Anticorrosion Coatings from Vegetable Oils

Bio-based epoxy resins are attracting widespread interest in the field of polymer thermosets as environmentally friendly building block. In the present study, the feasibility of applying UV-curable epoxidized vegetable oils (EVOs) as anti-corrosion coating is investigated. Rheological characterization of EVOs is carried out, and their viscosity-shear relationship is evaluated. The cationic UV-curing of EVOs successfully gives rise to crosslinked materials with a wide range of thermo-mechanical properties, evaluated by differential scanning calorimetric analysis and dynamic thermal mechanical analysis. A high epoxy-group conversion, ranging from 93% to 99%, is always obtained. The thermal stability and surface properties of the bio-based coatings, such as, pencil hardness, adhesion, solvent resistance, and contact angle, are analyzed. Moreover, the corrosion protection effectiveness of the coatings is characterized by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. In addition, field emission scanning electron microscopy is used to assess the samples morphology after corrosion tests.     

Studies on Verbenacea Seed Oils

Seed oils of Stachytarpheta mutabilis, Petrea volubilis, Gmelina hystrix were examined for their component acids and were found to contain the following acids (wt. %): Capric (0.5, -, 1.3), Lauric (0.5, 5.9, 1.5), Myristic (1.0, 8.9, 2.3), Palmitic (7.7, 10.7, 29.2), Stearic (5.4, 20.9, 21.1), Arachidic (1.1, 3.5, 6.3), Behenic (1.0, 4.2, 4.7), Oleic (9.1, 42.1, 2.9) and Linoleic (73.7, 3.8, 30.7) respectively.     

Studies on Apocynacea Seed Oils

The fatty acid composition of three seed oils of Apocynaceae has been studied in this investigation. The seed oils of Apocynaceae were examined for their component acids and were found to contain the following acids: Rauwolfia serpentina, Benth, (wt.%) lauric 0.2 %, myristic 0.8 %, palmitic 17.7%, stearic 4.9 %, arachidic 0.9 %, behenic 0.6 %, oleic 34.4 %, and linoleic 40.5 %. Rauwolfia tetraphylla, Linn. syn. Rauwolfia canescens, Linn., Rauwolfia heterophylla, Roem and Schult, (wt.%) lauric 0.9 %, myristic 3.4 %, palmitic 25.7 %, stearic 10.3%, arachidic 1.6%, behenic 1.4%, oleic 36.5 %, and linoleic 20.2 %. Vinca rosea Linn syn. Lochnera rosea, Linn. (wt.%) lauric 0.2%, myristic 1.0%, palmitic 1.4 %, stearic 6.8 %, arachidic 1.3 %, behenic 0.6 %, oleic 73.6 %, and linoleic 15.1 %.     

环氧植物油脂的制备及应用研究进展

对植物油脂的环氧化方法进行了综述,介绍了液体酸催化、固体酸催化、相转移催化及酶催化等制备环氧植物油脂的方法,并指出了各种方法的优点以及存在的问题。同时对环氧植物油脂在聚氨酯、环氧树脂、润滑剂等高分子领域的重要应用进行了总结,并对环氧植物油脂的发展进行了展望。     

Experience of Prerefining of Vegetable Oils with Acids

Prerefining of vegetable oils with acids serves general purposes. One is to remove impurities like phosphatides etc. from the crude oils to such a degree that the oil can then be physically refined. Another purpose is to facilitate subsequent alkali refining and to reduce pollution in effluent from alkali refining. After a review of some earlier work results from tests in laboratory scale on soya oil, rapeseed oil and linseed oil will be presented and discussed. Finally, an industrial procedure for acid refining, called “special degumming” will be described.     

The Glyceride Structure of Some Egyptian Vegetable Oils

Glyceride structure of seven vegetable oils of Egyptian origin have been determined by pancreatic lipase hydrolysis and gasliquid chromatography. Results thus obtained have been compared, for some of the oils, with those obtained by other methods of glyceride analysis. Four of these seed oils have been analysed for the first time for their glyceride structure: Cyperus esculentus, Solanum melongena, Capsicum annum and Phoenix dactylifera.     

Heterogeneously Catalyzed Esterification of FFAs in Vegetable Oils

The production of methyl esters (biodiesel) from free fatty acids (FFAs) contained in vegetable oils was studied using a heterogeneous acid catalyst. The feedstock was a by‐product of a vegetable oil refinery. The experiments were performed in a batch reactor, in a temperature range of 363.15–393.15 K, with an initial molar ratio of methanol to FFAs of 6.6/1, while the catalyst mass was fixed at 2 wt % of the total vegetable oil mass. A technical kinetic model has been developed which accounts for the reversible esterification reaction. Kinetic parameters were determined by fitting experimental data to the model.     

Highly Stable Nonionic Fatliquors Based on Ethoxylated Overused Vegetable Oils

Overused vegetable oils, which are considered to be a waste and available in huge quantities after frying processes, were directly ethoxylated using a conventional cheap catalyst in order to obtain an economically valuable ethoxylated product to replace the imported intermediate derivatives and at the same time the environment will be rid of one of its pollutants. Therefore, this work was devoted to exploring its application as a fatliquoring agent in the leather industry. Overused sunflower and olein oils were directly ethoxylated using ethylene oxide gas in the presence of 3% KOH catalyst at 180 °C for 20 h. The prepared products were applied as nonionic fatliquors. The fatliquoring process is the operation in which a fatty matter is introduced into the leather fibers. The results obtained showed that the prepared ethoxylated overused oils were effective fatliquors with high HLB values giving stable oil in water emulsion as well as high stability against acid, alkali and different metallic salts. The fatliquored leather had improved mechanical properties such as tensile strength and elongation at break. In addition, a significant enhancement of the texture of the treated leather by the two prepared fatliquors as indicated from the scanning electron microscope images was observed. Also the results indicated that ethoxylated overused sunflower oil gave better results than those of ethoxylated overused olein oil.     

Effect of the Addition of Chili Pepper Powder on Vegetable Oils Oxidative Stability

Red chili pepper represents an excellent source of functional bioactive compounds, and its use as food additive could be useful for protecting other products from spoilage. Olive oils show a limited shelf‐life due to a progressive quality deterioration linked mostly to oxidation reactions providing a loss of quality in terms of organoleptic and healthy properties. In this work, the addition of red chili pepper powder to virgin, extra‐virgin olive and sunflower oils was proved to be effective in improving their stability during 12 months of shelf‐life. Oil stability was monitored by employing the Oxitest system, based on accelerating the oxidation process. Three pepper powders of different pungency were added to the virgin olive oil samples with the aim of investigating whether capsaicinoids could be responsible for the observed effects. The strongest effect was recorded when employing the less pungent pepper showing that the protective effect could not be attributed to the capsaicinoids content. Besides, a screening on different oils demonstrated that the less stable samples received a stronger protective effect. The evaluation of a possible dose‐effect relation was also carried out pointing out that a threshold dose of about 1 % was required to record an effect. The results suggest potential perspectives in the field of food technology, as addition of a small amount of sweet pepper could be proposed to prolong food shelf‐life.     

海泡石的活化及其对植物油脱色性能的研究

通过对海泡石进行活化处理 ,研究了酸浓度、焙烧温度、焙烧时间、脱色温度及油土比等因素对海泡石吸附脱色性能的影响 ,探讨了海泡石对植物油脱色的最佳条件 ,结果表明 ,海泡石活性土脱色效果优于国产活性白土 ,可作为一种新型的植物油脱色剂应用于植物油的精炼脱色