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1.
Vegetable oils have significant potential as a base fluid and a substitute for mineral oil in grease formulation. Preparation of soybean oil-based lithium greases using a variety of fatty acids in the soap structure is discussed in this paper. Soy greases with lithium-fatty acid soap having C12-C18 chain lengths and different metal to fatty acid ratios were synthesized. Grease hardness was determined using a standard test method, and their oxidative stabilities were measured using pressurized differential scanning calorimetry. Results indicate that lithium soap composition, fatty acid types, and base oil content significantly affect grease hardness and oxidative stability. Lithium soaps prepared with short-chain fatty acids resulted in softer grease. Oxidative stability and other performance properties will deteriorate if oil is released from the grease matrix due to overloading of soap with base oil. Performance characteristics are largely dependent on the hardness and oxidative stability of grease used as industrial and automotive lubricant. Therefore, this paper discusses the preparation methods, optimization of soap components, and antioxidant additive for making soy-based grease.  相似文献   

2.
Vegetable oils have significant potential as a base fluid and a substitute for mineral oil for grease formulation. This paper describes the preparation of biobased grease with high oxidative stability and a composition useful for industrial, agriculture/farming equipment, and forestry applications. The process utilizes more oxidatively stable epoxy vegetable oils as the base fluid, metal-soap thickener, and several specialty chemicals identified to address specific applications. Performance characteristics of greases used for industrial and automotive applications are largely dependent on the hardness and the oxidative stability of grease. Grease hardness was determined using standard test methods, and their oxidative stabilities were determined using pressurized differential scanning calorimetry and rotary bomb oxidation tests. Wear data were generated using standard test methods in a four-ball test geometry. Results indicate that grease developed with this method can deliver at par or better performance properties (effective lubrication, wear protection, corrosion resistance, friction reduction, heat removal, etc.) than existing mineral oil-based greases currently used in similar trades. Therefore, developed greases can be a good substitute for mineral oil-based greases in industrial, agriculture, forestry, and marine applications.  相似文献   

3.
The environment must be protected against pollution caused by lubricants based on petroleum oils. The pollution problem is so severe that approximately 50% of all lubricants sold worldwide end up in the environment via volatility, spills, or total loss applications. This threat to the environment can be avoided by either preventing undesirable losses, reclaiming and recycling mineral oil lubricants, or using environmentally friendly lubricants. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment friendly lubricants. Lubricants based on vegetable oils display excellent tribological properties, high viscosity indices, and flash points. To compete with mineral-oil-based lubricants, some of their inherent disadvantages, such as poor oxidation and low-temperature stability, must be corrected. One way to address these problems is chemical modification of vegetable oils at the sites of unsaturation. After a one-step chemical modification, the chemically modified soybean oil derivatives were studied for thermo-oxidative stability using pressurized differential scanning calorimetry and a thin-film micro-oxidation test, low-temperature fluid properties using pour-point measurements, and friction-wear properties using four-ball and ball-on-disk configurations. The lubricants formulated with chemically modified soybean oil derivatives exhibit superior low-temperature flow properties, improved thermo-oxidative stability, and better friction and wear properties. The chemically modified soybean oil derivatives having diester substitution at the sites of unsaturation have potential in the formulation of industrial lubricants.  相似文献   

4.
Vegetable oils are promising candidates as substitutes for petroleum base oils in lubricant applications, such as total loss lubrication, military applications, and outdoor activities. Although vegetable oils have some advantages, they also have poor oxidation and low temperature stability. One of the ways to address these issues is chemical modification of fatty acid chain of triglyceride. We report a one-pot synthesis of a novel class of chemically modified vegetable oils from epoxidized triacylglycerols and various anhydrides. In an anhydrous solvent, boron trifluoride etherate is used as catalyst to simultaneously open the oxirane ring and activate the anhydride. The reaction was monitored and products confirmed by NMR, FTIR, GPC, and TGA analysis. Experimental conditions were optimized for research quantity and laboratory scale-up (up to 4 lbs). The resultant acyl derivatives of vegetable oil, having diester substitution at the sites of unsaturation, have potential in formulation of industrial fluids such as hydraulic fluids, lubricants, and metal working fluids.  相似文献   

5.
This paper describes the composition of authentic hazelnut oils obtained from nuts collected from five countries that are major suppliers of hazelnut oil. Oils were analyzed using standard methods for fatty acids, fatty acids in the triacylglycerol 2-position, tocopherols and tocotrienols, triacylglycerols, sterols, steradienes, and iodine value. The results were generally in good agreement with those of other publications. Tocotrienols, previously unreported in hazelnut oil, were detected in one sample. There were no major differences in the composition of oils from different countries. Roasting the nuts prior to pressing had little effect on oil composition.  相似文献   

6.
The physicochemical and stability properties as well as the fatty acid, triacylglycerol, sterol, and triterpenic dialcohol compositions of Tunisian olive oil varieties were analyzed. On the basis of our results, we classified all of the monovarietal oils into the extra virgin category. Oleic and linoleic acids were the most useful fatty acids to discriminate three cultivars, Neb Jmel, Chétoui, and Ain Jarboua, from the others. Of the six monovarietal virgin olive oils analyzed, the main triacylglycerols were OOO, POO, PLO plus SLL, and OLO, which was expected given the high oleic acid and low linoleic and linolenic acids content observed in total fatty acids. In total, these accounted for more than 80% of the total HPLC chromatogram peak area. The main sterols found were beta-sitosterol, Delta5-avenasterol, and campesterol. The statistical analysis showed significant differences between oil samples, and the obtained results showed a great variability in the oil composition between cultivars, which is influenced exclusively by genetic factors.  相似文献   

7.
Most common seed oils contain small amounts of very long chain fatty acids (VLCFAs), the main components of oils from species such as Brassica napus or Lunnaria annua. These fatty acids are synthesized from acyl-CoA precursors in the endoplasmic reticulum through the activity of a dissociated enzyme complex known as fatty acid elongase. We studied the synthesis of the arachidic, behenic, and lignoceric VLCFAs in sunflower kernels, in which they account for 1-3% of the saturated fatty acids. These VLCFAs are synthesized from 18:0-CoA by membrane-bound fatty acid elongases, and their biosynthesis is mainly dependent on NADPH equivalents. Two condensing enzymes appear to be responsible for the synthesis of VLCFAs in sunflower kernels, beta-ketoacyl-CoA synthase-I (KCS-I) and beta-ketoacyl-CoA synthase-II (KCS-II). Both of these enzymes were resolved by ion exchange chromatography and display different substrate specificities. While KCS-I displays a preference for 20:0-CoA, 18:0-CoA was more efficiently elongated by KCS-II. Both enzymes have different sensitivities to pH and Triton X-100, and their kinetic properties indicate that both are strongly inhibited by the presence of their substrates. In light of these results, the VLCFA composition of sunflower oil is considered in relation to that in other commercially exploited oils.  相似文献   

8.
The authenticity of vegetable oils consumed in Slovenia and Croatia was investigated by carbon isotope analysis of the individual fatty acids by the use of gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS), and through carbon isotope analysis of the bulk oil. The fatty acids from samples of olive, pumpkin, sunflower, maize, rape, soybean, and sesame oils were separated by alkaline hydrolysis and derivatized to methyl esters for chemical characterization by capillary gas chromatography/mass spectrometry (GC/MS) prior to isotopic analysis. Enrichment in heavy carbon isotope ((13)C) of the bulk oil and of the individual fatty acids are related to (1) a thermally induced degradation during processing (deodorization, steam washing, or bleaching), (2) hydrolytic rancidity (lipolysis) and oxidative rancidity of the vegetable oils during storage, and (3) the potential blend with refined oil or other vegetable oils. The impurity or admixture of different oils may be assessed from the delta(13)C(16:0) vs. delta(13)C(18:1) covariations. The fatty acid compositions of Slovenian and Croatian olive oils are compared with those from the most important Mediterranean producer countries (Spain, Italy, Greece, and France).  相似文献   

9.
Interest in biodegradable materials for packaging and agricultural uses has grown in recent years. Plant proteins have been proposed as inexpensive, renewable, and abundant feedstock. Corn zein was investigated based on value-added considerations and on the unique thermoplastic and hydrophobic properties of zein. Films prepared from zein are known to be tough and resistant, but also hard and brittle, thus requiring the addition of plasticizers to improve flexibility. The objectives of this research were to study the tensile properties, water absorption, and microstructure of zein sheets plasticized with palmitic and stearic acids. Both palmitic and stearic acids showed similar effects as plasticizers of zein. Tensile strength of zein sheets increased with the addition of low levels of plasticizers. However, beyond a critical point, tensile strength decreased with further addition of fatty acids. Water absorption decreased continuously with increasing fatty acid content. Kinetic parameters indicated fatty acids decreased water absorption by decreasing the saturation level of zein sheets. Coating zein with flax oil decreased the rate of water absorption by sealing off surface pores. Scanning electron micrographs of zein sheets showed the development of layered structures as fatty acid content increased. Zein-fatty acid layers were believed to be responsible for the increased tensile strength of plasticized zein sheets and to have contributed to increased resistance to water absorption.  相似文献   

10.
Because Mexico is the number one producer of avocados in the world, this fruit has potential as a source for oil extraction. It is appropriate to further investigate the detailed changes that the oil undergoes when different extraction methods are applied. This research paper presents the study of the physical and chemical changes, the fatty acids profile, the trans fatty acid content, and the identification of volatile compounds of the oils from avocado pulp (Persea americana Mill.), obtained by four different extraction methods. The method with the greatest extraction yield was the combined microwave-hexane method. The amount of trans fatty acids produced in the microwave-squeezing treatment was <0.5 g/100 g. On the other hand, the amounts of trans fatty acids produced with the hexane and acetone treatments were 0.52 and 0.87 g/100 g, respectively. The method that caused the slightest modification to the oil quality was a novel combined extraction method of microwave-squeezing proposed by the authors.  相似文献   

11.
Solvent-free lipase-catalyzed preparation of diacylglycerols   总被引：6，自引：0，他引：6  
Various methods have been applied for the enzymatic preparation of diacylglycerols that are used as dietary oils for weight reduction in obesity and related disorders. Interesterification of rapeseed oil triacylglycerols with commercial preparations of monoacylglycerols, such as Monomuls 90-O18, Mulgaprime 90, and Nutrisoft 55, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) in vacuo at 60 degrees C led to extensive (from 60 to 75%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with Nutrisoft, catalyzed by Lipozyme RM in vacuo at 60 degrees C, also led to extensive (from 60 to 70%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme RM and lipases from Thermomyces lanuginosus (Lipozyme TL IM) and Candida antarctica (lipase B, Novozym 435), also provided diacylglycerols, however, to a lower extent (40-45%). Glycerolysis of rapeseed oil triacylglycerols with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme TL and Novozym 435, led to diacylglycerols to the extent of 相似文献   

12.
Cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils were evaluated for their fatty acid composition, carotenoid content, tocopherol profile, total phenolic content (TPC), oxidative stability index (OSI), peroxide value, and antioxidant properties. All tested seed oils contained significant levels of alpha-linolenic acid ranging from 19.6 to 32.4 g per 100 g of oil, along with a low ratio of n-6/n-3 fatty acids (1.64-3.99). The total carotenoid content ranged from 12.5 to 30.0 micromoles per kg oil. Zeaxanthin was the major carotenoid compound in all tested berry seed oils, along with beta-carotene, lutein, and cryptoxanthin. Total tocopherol was 260.6-2276.9 mumoles per kg oil, including alpha-, gamma-, and delta-tocopherols. OSI values were 20.07, 20.30, and 44.76 h for the marionberry, red raspberry, and boysenberry seed oils, respectively. The highest TPC of 2.0 mg gallic acid equivalents per gram of oil was observed in the red raspberry seed oil, while the strongest oxygen radical absorbance capacity was in boysenberry seed oil extract (77.9 micromol trolox equivalents per g oil). All tested berry seed oils directly reacted with and quenched DPPH radicals in a dose- and time-dependent manner. These data suggest that the cold-pressed berry seed oils may serve as potential dietary sources of tocopherols, carotenoids, and natural antioxidants.  相似文献   

13.
Although poppy seed oil is an expensive article of trade, no literature about identification methods for adulteration with cheaper vegetable oils, like sunflower oil, has been published. This kind of adulteration is a challenge for routine analytical methods, such as the determination of fatty acid composition, because of almost similar fatty acid ratios. The detection of adulteration of poppy seed oils with sunflower oils at different levels (5-40%, w/w) by using SPME-GC-MS and MALDI-ToF-MS is the subject of our investigation. With the mentioned SPME-GC-MS method, it was possible to detect an admixture of sunflower oils in all relevant (5-40%) amounts by using alpha-pinene as a marker compound. Admixture of sunflower oil with high levels of triolein (high-oleic acid type) could be undoubtedly detected by MALDI-MS down to the 5-10% level. In contrast, adulteration of pure poppy seed oil by "standard" sunflower oils remained indistinguishable using this MALDI-MS.  相似文献   

14.
In an effort to investigate the effect of positional distribution on oxidative stability of menhaden and seal blubber oils, Novozyme 435 was used as a random biocatalyst. Positional distribution of fatty acids was determined using gas chromatography. As some of the α-tocopherol was lost during randomization, its content was adjusted to the level prior to the process to eliminate this effect on oxidative stability of oils tested. Conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS) were used as indicators of oxidative stability. The results showed that the polyunsaturated fatty acids were distributed predominantly at terminal positions in randomized menhaden oil, whereas they were distributed more evenly among all positions in enzymatically randomized seal blubber oil, compared to their unrandomized counterparts. Results of CD and TBARS values indicated that randomized menhaden oil was more stable than the original oil, whereas randomized seal blubber oil was more vulnerable to oxidation compared to its counterpart. Changes of oxidative stability after randomization were mainly due to positional redistribution of fatty acids, especially those of the polyunsaturated types.  相似文献   

15.
Evidence that dietary lycopene decreases the risk for a number of health conditions has generated new opportunities for the addition of lycopene to functional foods. This work examined the potential of oil-in-water emulsions as a lycopene delivery system for foods. Oil-in-water emulsions containing lycopene were prepared using different kinds of surfactant (cationic, anionic, and nonionic) and oil types (corn oil, stripped corn oil, and hexadecane). The formation of fatty acid oxidation products and the degradation of lycopene and tocopherol were then monitored. Fatty acids and lycopene had greater stability in oil-in-water emulsions stabilized by cationic dodecyltrimethylammonium bromide (DTAB) or nonionic polyoxyethylene (23) lauryl ether than by anionic sodium dodecyl sulfate (SDS). Oxidative stability in the corn oil-in-water emulsions stabilized by SDS was in the following order: tocopherolhexadecane>tocopherol-stripped corn oil. Lycopene degradation rates were similar in emulsions with and without fatty acids, suggesting that lycopene loss was independent of the presence of fatty acids. These results suggest that the stability of lycopene in oil-in-water emulsions could be inhibited by altering the emulsion droplet interface and by the presence of tocopherols.  相似文献   

16.
苦杏仁去皮热风干燥适宜温度提高油脂品质   总被引：4，自引：1，他引：3  
为探索适宜的杏仁热风干燥温度,以热烫去皮处理后的湿杏仁为试验材料,研究了热风干燥不同温度对杏仁及其油脂的感官、理化和营养品质的影响。结果表明,经热烫去皮、干燥处理后可以得到颜色较浅的杏仁油,有利于提高杏仁油的感官品质,但会造成杏仁油过氧化值显著升高(P0.05),油酸、亚油酸、十七碳烯酸、二十碳一烯酸等不饱和脂肪酸的比例和甾醇含量降低,棕榈酸、棕榈油酸、硬脂酸、十七碳烷酸、二十碳烷酸、二十碳一烯酸的比例和总生育酚含量升高,对杏仁油的理化特性和营养品质产生影响。但不同脂肪酸及其伴随物种类、不同温度处理变化幅度不同。随着干燥温度的提高,干燥速率逐渐加快,杏仁及杏仁油的颜色逐渐加深,杏仁油亮度下降,酸价略有升高,但不同干燥温度之间差异不显著(P0.05);过氧化值呈上升趋势,且80℃以上干燥处理显著高于40℃和60℃干燥处理(P0.05);总不饱和脂肪酸、油酸、亚油酸、十七碳烯酸、二十碳烷酸的比例及β-生育酚、δ-生育酚及总生育酚含量总体呈下降趋势,棕榈油酸、棕榈酸、硬脂酸的比例和β-谷甾醇、总甾醇含量总体呈升高趋势。低温干燥有利于提高杏仁油中生育酚含量,而提高干燥温度则有利于杏仁油中植物甾醇含量的提高。尤其是干燥温度为80℃以上时,杏仁油的品质变化加快。因此,为提高杏仁油理化与营养品质,杏仁脱皮后的干燥宜在80℃以下的较低温度条件下进行。研究结果可为杏仁干燥和高品质杏仁油加工提供参考。  相似文献   

17.
The chemical composition (fatty acids, tocopherols, and sterols) of the oil from 14 samples of turpentine (Pistacia terebinthus L.) fruits is presented in this study. The oil content of the samples varied in a relatively small range between 38.4 g/100 g and 45.1 g/100 g. The dominating fatty acid of the oil is oleic acid, which accounted for 43.0 to 51.3% of the total fatty acids. The total content of vitamin E active compounds in the oils ranged between 396.8 and 517.7 mg/kg. The predominant isomers were alpha- and gamma-tocopherol, with approximate equal amounts between about 110 and 150 mg/kg. The seed oil of P. terebinthus also contained different tocotrienols, with gamma-tocotrienol as the dominate compound of this group, which amounted to between 79 and 114 mg/kg. The total content of sterols of the oils was determined to be between 1341.3 and 1802.5 mg/kg, with beta-sitosterol as the predominent sterol that accounted for more than 80% of the total amount of sterols. Other sterols in noteworthy amounts were campesterol, Delta5-avenasterol, and stigmasterol, which came to about 3-5% of the total sterols.  相似文献   

18.
Enzymatic approach to biodiesel production   总被引：5，自引：0，他引：5  
The need for alternative energy sources that combine environmental friendliness with biodegradability, low toxicity, renewability, and less dependence on petroleum products has never been greater. One such energy source is referred to as biodiesel. This can be produced from vegetable oils, animal fats, microalgal oils, waste products of vegetable oil refinery or animal rendering, and used frying oils. Chemically, they are known as monoalkyl esters of fatty acids. The conventional method for producing biodiesel involves acid and base catalysts to form fatty acid alkyl esters. Downstream processing costs and environmental problems associated with biodiesel production and byproducts recovery have led to the search for alternative production methods and alternative substrates. Enzymatic reactions involving lipases can be an excellent alternative to produce biodiesel through a process commonly referred to alcoholysis, a form of transesterification reaction, or through an interesterification (ester interchange) reaction. Protein engineering can be useful in improving the catalytic efficiency of lipases as biocatalysts for biodiesel production. The use of recombinant DNA technology to produce large quantities of lipases, and the use of immobilized lipases and immobilized whole cells, may lower the overall cost, while presenting less downstream processing problems, to biodiesel production. In addition, the enzymatic approach is environmentally friendly, considered a "green reaction", and needs to be explored for industrial production of biodiesel.  相似文献   

19.
A number of reference oils, two commercial oils, and several oil extracts from seeds of Nicotiana species were analyzed for the fatty acid content and also for triglyceride composition. The seed oils were obtained using an accelerated solvent extraction procedure, which was proven to be very efficient and reproducible. The fatty acids were analyzed after the hydrolysis of the oils, using trimethylsilylation and gas chromatography/mass spectrometry (GC/MS) analysis. The levels of sixteen molecular species of triglycerides in the oils were measured after GC separation using MS for identification and flame ionization detection (FID) for quantitation. The results for the fatty acids and those for triglycerides were combined to generate uniform information regarding the composition of the analyzed oils. For a number of oils, the individual triglyceride quantitation and mass spectra were reported for the first time. The study showed that in some cases, oils with similar fatty acid content do not have the same triglycerides profile. The fatty acids and triglycerides profile for selected Nicotiana species were described for the first time in the literature.  相似文献   

20.
The formation and evolution of monoepoxy fatty acids, arising from oleic and linoleic acids, were investigated in olive oil and conventional sunflower oil, representatives of monounsaturated and polyunsaturated oils, respectively, during thermoxidation at 180 degrees C for 5, 10, and 15 h. Six monoepoxy fatty acids, cis-9,10- and trans-9,10-epoxystearate, arising from oleic acid, and cis-9,10-, trans-9,10-, cis-12,13-, and trans-12,13-epoxyoleate, arising from linoleic acid, were analyzed by gas chromatography after oil derivatization to fatty acid methyl esters. Considerable amounts, ranging from 4.29 to 14.24 mg/g of oil in olive oil and from 5.10 to 9.44 mg/g of oil in sunflower oil, were found after the heating periods assayed. Results showed that the monoepoxides quantitated constituted a major group among the oxidized fatty acid monomers formed at high temperature. For similar levels of degradation, higher contents of the monoepoxides were found in olive oil than in sunflower oil. Ten used frying oils from restaurants and fried-food outlets in Spain were analyzed to determine the contents of the monoepoxides in real frying oil samples. Levels ranged from 3.37 to 14.42 mg/g of oil. Results show that, for similar degradation levels, the monoepoxides were more abundant in the monounsaturated oils than in the polyunsaturated oils.  相似文献   

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