Showing papers on "Soybean oil published in 2001"

Biodiesel production from oils and fats with high free fatty acids

Abstract: Biodiesel is an alternative fuel for diesel engines consisting of the alkyl monoesters of fatty acids from vegetableoils or animal fats. Most of the biodiesel that is currently made uses soybean oil, methanol, and an alkaline catalyst. The highvalue of soybean oil as a food product makes production of a costeffective fuel very challenging. However, there are largeamounts of lowcost oils and fats such as restaurant waste and animal fats that could be converted to biodiesel. The problemwith processing these low cost oils and fats is that they often contain large amounts of free fatty acids (FFA) that cannot beconverted to biodiesel using an alkaline catalyst. In this study, a technique is described to reduce the free fatty acids contentof these feedstocks using an acidcatalyzed pretreatment to esterify the free fatty acids before transesterifying the triglycerideswith an alkaline catalyst to complete the reaction. Initial process development was performed with synthetic mixturescontaining 20% and 40% free fatty acids, prepared using palmitic acid. Process parameters such as the molar ratio of alcohol,type of alcohol, acid catalyst amount, reaction time, and free fatty acids level were investigated to determine the best strategyfor converting the free fatty acids to usable esters. The work showed that the acid level of the high free fatty acids feedstockscould be reduced to less than 1% with a 2step pretreatment reaction. The reaction mixture was allowed to settle betweensteps so that the watercontaining alcohol phase could be removed. The 2step pretreatment reaction was demonstrated withactual feedstocks, including yellow grease with 12% free fatty acids and brown grease with 33% free fatty acids. After reducingthe acid levels of these feedstocks to less than 1%, the transesterification reaction was completed with an alkaline catalystto produce fuelgrade biodiesel.

Physicochemical and Antimicrobial Properties of New Rhamnolipids Produced by Pseudomonas aeruginosa AT10 from Soybean Oil Refinery Wastes

Abstract: The rhamnolipids produced by Pseudomonas aeruginosa strains are often a mixture of several homologues. Up to seven (R2C10C10 + R1C10C10 + R2C10C12 + R1C10C12 + R1C12:1C10 + R1C12:2 + R1C8:2 ) have been identified in cultures of P. aeruginosa AT10 from soybean oil refinery wastes. This study deals with the production, purification, and identification of rhamnolipids in the mixture (M7), as well as their physical and chemical characterization and the evaluation of their antimicrobial properties. The surface tension decreases to 26.8 mN/m and the critical micelle concentration value to 1.2 × 102 mg/L. These molecules show excellent antifungal properties against Aspergillus niger and Gliocadium virens (16 μg/mL) and C. globosum, P. crysogenum, and A. pullulans (32 μg/mL), whereas the growth of the phytopathogenic fungi B. Cinerea and R. solani was inhibited at 18 μg/mL.

Engine Performance of Biodiesel Fuel Prepared from Soybean Soapstock: A High Quality Renewable Fuel Produced from a Waste Feedstock‖

Abstract: A previously developed bench-scale method for the production of fatty acid methyl esters (biodiesel) from soybean soapstock (Haas, M. J.; Bloomer, S.; Scott, K. J. Am. Oil Chem. Soc. 2000, 77, 373−379) was taken to the small pilot scale, producing approximately 2.5 L of material per run. By multiple successive reactions, 25 L of product was accumulated. The fatty acid composition of the ester product (wt %) was palmitic: 16.2, stearic: 4.7, oleic: 16.2, linoleic: 54.4, and linolenic: 6.9. This mirrors the fatty acid composition of soy soapstock and is quite similar to that of commercial biodiesel produced from refined soybean oil. The ester product met the provisional biodiesel specifications of the American Society for Testing and Materials with regard to all variables examined: flash point, water and sediment, carbon residue, sulfated ash, density, kinematic viscosity, sulfur, cetane number, cloud point, copper corrosion, acid number, free glycerin, and total glycerin, and had density and iodine n...

Microencapsulating properties of sodium caseinate.

Abstract: Emulsions were prepared with 5% (w/v) solutions of sodium caseinate (Na Cas) and soy oil at oil/protein ratios of 0.25-3.0 by homogenization at 10--50 MPa. Emulsions were spray-dried to yield powders with 20--75% oil (w/w). Emulsion oil droplet size and interfacial protein load were determined. Microencapsulation efficiency (ME), redispersion properties, and structure of the powders were analyzed. The size of emulsion oil droplets decreased with increasing homogenization pressure but was not influenced by oil/protein ratio. Emulsion protein load values were highest at low oil/protein ratios. ME of the dried emulsions was not affected by homogenization pressure but decreased from 89.2 to 18.8% when the oil/protein ratio was increased from 0.25 to 3.0, respectively. Mean particle sizes of reconstituted dried emulsions were greater than those of the original emulsions, particularly at high oil/protein ratios (>1.0), suggesting destabilization of high-oil emulsions during the spray-drying process.

Calcium carbonate catalyzed alcoholysis of fats and oils

Abstract: Several alcoholysis catalysts, known to be effective for reactions between simple alcohols and soybean oil, were evaluated and found to be ineffective toward alcoholysis of ethylene glycol with soybean oil under traditional reaction conditions An initial survey of alternative catalysts revealed that organometallic tin complexes were effective but unsatisfactory due to toxicity and difficulty in recovering the catalyst Satisfactory performance for several alcoholysis reactions was achieved with calcium carbonate catalysts even though at higher temperatures, typically greater than 200°C Higher reaction temperatures are not considered to be a problem for flow reactors where heat exchangers can be readily used to minimize energy costs Free fatty acids were esterified by the calcium carbonate and did not appear to inhibit the catalyst Reaction times of 18 min provided essentially complete conversion No decrease in the activity of calcium carbonate was observed after weeks of utilization The robust structure is suitable for use in packed-bed reactors The catalyst used for the flow reactors was pulverized limestone Limestone from two locations was tested and found to be effective Catalyst removal requires only a screening process at the reactor discharge

Modification of epoxidized soybean oil for lubricant formulations with improved oxidative stability and low pour point

Abstract: To produce soybean oil-based lubricants with good oxidative stability and low pour point, epoxidized soybean oil (SBO) was chemically modified. Epoxidized SBO was reacted with various alcohols in the presence of sulfuric acid as a catalyst to give a ring-opened intermediate product. In this step, the epoxy group was transformed to the functional group of-CH(OR1)CH(OH)-(where the R1=methyl, 1-butyl, 2-butyl, 1-hexyl, cyclohexyl, 2,2-dimethyl-1-propyl, or 1-decyl). The 1H nuclear magnetic resonance spectra of the products indicated that transesterification was accompanied by the ringopening reaction except when the bulky 2,2-dimethyl-1-propanol was used. Acid anhydride was used to esterify the hydroxy groups in the ring-opened product. This resulted in a fluid that is a lubricant candidate with the functional group of −CH(OR1)CH(OCOR2)−. Pour point studies of the resulting products showed that the pour points varied with the substituents, R1 and R2. Products with R1=CH3(CH2)5− and R2=CH3(CH2)2−, (CH3)2CH−, or CH3(CH2)4-showed the lowest pour points (−39, −39, and −45°C, respectively) when 1% of pour point depressant was added. For the oxidative stability test, two products, in which R1, R2=CH3(CH2)5−, (CH3)2CH− and R1, R2=CH3(CH2)5−, CH3(CH2)4−, were chosen for a modified Penn State micro-oxidation test. In the oxidative stability test, the products gave 69–71% of oxidative evaporation and 10–17% of tetrahydrofuran-insoluble deposits in 3 h at 175°C. The amounts of deposits were much lower than those of soybean oil (96%) and epoxidized SBO (83%) and even less than those of most petroleum-based lubricant basestocks (3–93%).

Formation of polycyclic aromatic hydrocarbons in the smoke from heated model lipids and food lipids.

Abstract: The contents of polycyclic aromatic hydrocarbons (PAHs) in the smoke from model lipids and food lipids during heating were determined and the mechanism of PAH formation was studied. A Rancimat oil stability analyzer was used as a model system for heating model lipids and food lipids at 220 degrees C for 2 h and for adsorption of smoke. The various lipid degradation products and PAHs in the smoke were identified and quantified by a GC/MS technique. Results showed that model lipids were more susceptible to smoke formation than food lipids during heating, but the PAH levels were lower for the former than latter. Methyl linolenate produced the highest amount of PAHs, followed by methyl linoleate, methyl oleate, and methyl stearate. Also, soybean oil generated a larger amount of PAHs than canola oil or sunflower oil. Benzene-like compounds were found to be possible precursors for PAHs formation. Several PAH derivatives were also present in heated model lipids and food lipids.

Rigid, thermosetting liquid molding resins from renewable resources. I. Synthesis and polymerization of soy oil monoglyceride maleates

Abstract: In this study, rigid thermoset polymers were prepared from radical copolymerization of the soybean oil monoglyceride maleates with styrene In the first part of the study, soybean oil monoglycerides (SOMGs) were obtained from the reaction of soybean oil with glycerol at 220–240°C with an optimization of the reaction to maximize the monoglyceride yield In the following step, SOMG were reacted with maleic anhydride at temperatures around 100°C to produce the SOMG maleate half esters Different catalysts and different reaction conditions were examined to increase the maleate half esters' yields The reactions were followed by IR and 1H NMR, and the products were characterized by mass spectrometry In the final step, the radical initiated copolymerization of the SOMG maleates with styrene produced rigid, thermoset polymers The emulsion copolymerization of the SOMG maleates with styrene was also carried out successfully without the addition of an emulsifier The obtained polymers were characterized by IR and the crosslinked network structure of the copolymers was examined with the swelling behavior in different solvents Mechanical properties of the cured resin such as Tg, dynamic flexural modulus, and surface hardness were also determined © 2001 John Wiley & Sons, Inc J Appl Polym Sci 81: 69–77, 2001

Kinetics of in situ epoxidation of soybean oil in bulk catalyzed by ion exchange resin

Abstract: The kinetics of the epoxidation of soybean oil in bulk by peracetic acid formed in situ, in the presence of an ion exchange resin as the catalyst, was studied. The proposed kinetic model takes into consideration two side reactions of the epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups as well as the reactions of the formation of the peracid and epoxy groups. The catalytic reaction of the peracetic acid formation was characterized by adsorption of only acetic acid and peracetic acid on the active catalyst sites, and irreversible surface reaction was the overall rate-determining step. Kinetic parameters were estimated by fitting experimental data using the Marquardt method. Good agreement between the calculated and experimental data indicated that the proposed kinetic model was correct. The effect of different reaction variables on epoxidation was also discussed. The conditions for obtaining optimal epoxide yield (91% conversion, 5.99% epoxide content in product) were found to be: 0.5 mole of glacial acetic acid and 1.1 mole of hydrogen peroxide (30% aqueous solution) per mole of ethylenic unsaturation, in the presence of 5 wt% of the ion exchange resin at 75°C, over the reaction period of 8 h.

New soybean oil–styrene–divinylbenzene thermosetting copolymers. I. Synthesis and characterization

Abstract: The cationic copolymerization of regular soybean oil, low-saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and divinylbenzene initiated by boron trifluoride diethyl etherate (BF3·OEt2) or related modified initiators provides viable polymers ranging from soft rubbers to hard, tough, or brittle plastics. The gelation time of the reaction varies from 1 × 102 to 2 × 105 s at room temperature. The yields of bulk polymers are essentially quantitative. The amount of crosslinked polymer remaining after Soxhlet extraction ranges from 80 to 92%, depending on the stoichiometry and the type of oil used. Proton nuclear magnetic resonance spectroscopy and Soxhlet extraction data indicate that the structure of the resulting bulk polymer is a crosslinked polymer network interpenetrated with some linear or less-crosslinked triglyceride oil–styrene–divinylbenzene copolymers, a small amount of low molecular weight free oil, and minor amounts of initiator fragments. The bulk polymers possess glass-transition temperatures ranging from approximately 0 to 105°C, which are comparable to those of commercially available rubbery materials and conventional plastics. Thermogravimetric analysis (TGA) indicates that these copolymers are thermally stable under 200°C, with temperatures at 10% weight loss in air (T10) ranging from 312 to 434°C, and temperatures at 50% weight loss in air (T50) ranging from 445 to 480°C. Of the various polymeric materials, the conjugated LoSatSoy oil polymers have the highest glass-transition temperatures (Tg) and thermal stabilities (T10). The preceding properties that suggest that these soybean oil polymers may prove useful where petroleum-based polymeric materials have found widespread utility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 658–670, 2001

Dietary Fatty Acid Composition in Pregnancy Alters Neurite Membrane Fatty Acids and Dopamine in Newborn Rat Brain

Abstract: The importance of maternal dietary fatty acids on arachidonic acid [AA; 20:4(n-6)] and docosahexaenoic acid [DHA; 22:6(n-3)] in fetal brain nerve growth cone membranes and monoaminergic neurotransmitters was investigated. Rats were fed purified diets containing 20 g/100 g safflower oil with 74.3% 18:2(n-6), 0.2% 18:3(n-3), soybean oil with 55.4% 18:2(n-6), 7.7% 18:3(n-3) or high fish oil with 24.6% 22:6(n-3) through gestation. Tissue for rats within a litter were pooled at birth, brain growth cone membranes prepared and phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) fatty acids quantified by gas-liquid chromatography. Dopamine, serotonin, and the metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxyindolacetic acid were quantified by HPLC. Growth cone membranes from offspring of rats fed safflower oil had significantly lower, and offspring of rats fed high 22:6(n-3) fish oil had significantly higher 22:6(n-3) in PE, PS and PI than the soybean oil group. The growth cone membrane PC, PE and PS 20:4(n-6) was significantly lower in the fish oil than in the soybean or safflower oil groups. Serotonin concentration was significantly higher in brain of offspring in the safflower oil compared with the soybean oil group. The newborn brain dopamine was inversely related to PE DHA and PS DHA (P < 0.001), but positively related to PC AA (P < 0.05). These studies show that maternal dietary fatty acids may alter fetal brain growth cone (n-6) and (n-3) fatty acids, and neurotransmitters involved in neurite extension, target finding and synaptogenesis. The functional importance, however, is not known at this time.

Preparation of Conjugated Soybean Oil and Other Natural Oils and Fatty Acids by Homogeneous Transition Metal Catalysis

Abstract: The use of as little as 0.1 mol% [RhCl(C8H14)2]2, 0.25 mol% PtCl2(PPh3)2, or 0.5 mol% RuHCl(CO)(PPh3)3, where Ph = phenyl, catalyzes the isomerization of soybean oil to conjugated soybean oil under mild reaction conditions and in high yields. No hydrogenation products are detected with any of these catalysts. Preliminary physical tests have shown that the conjugated soybean oil has exceptional drying properties and the resulting coatings exhibit good solvent resistance. The [RhCl(C8H14)2]2 catalyst provides similarly high yields of other conjugated vegetable oils, conjugated linoleic acid, and conjugated ethyl linoleate. Other rhodium catalysts, such as RhCl(PPh3)3, have also been found to be effective for the conjugation of ethyl linoleate.

Oxidation process affecting fatty acids and cholesterol in fried and roasted salmon.

Abstract: Salmon was processed by three different culinary techniques: pan-frying with olive oil, pan-frying with soya oil, and roasting. Roasting did not modify the fat content from that of raw samples. Frying increased the fat content 2-fold, with no difference between samples fried with different oils. Total cholesterol oxidized products (COPs) were 0.74, 2.98, 3.35, and 7.38 microg/g fat in raw, fried with olive oil, fried with soya oil, and roasted salmon, respectively, which represent 0.01, 0.08, 0.09, and 0.15% of cholesterol. A significant correlation (r = 0.902, < or = 0.01) was found between acidity index and total COPs. The most abundant COPs were 7-ketocholesterol, which appeared in all the samples, and cholestanetriol (one of the most citotoxic COP), which appeared only in cooked samples (1.05-1.33 microg/g fat). All cooked samples supplied more omega-6 polyunsaturated fatty acids (PUFAs) than raw samples and showed higher omega-6/omega-3 ratios. Roasted salmon showed the lowest omega-3 content and the highest PUFAs/(SFAs)-C18:0 and MUFAs+PUFAs/(SFAs-C18:0) ratios.

Oxidized Frying Oil Up-Regulates Hepatic Acyl-CoA Oxidase and Cytochrome P450 4 A1 Genes in Rats and Activates PPARα

Abstract: Oxidized LDL (oxLDL) and its component hydroxy fatty acids were shown to activate peroxisome proliferator-activating receptor alpha (PPARalpha) and gamma (PPARgamma). To test the hypothesis that lipid oxidation products in oxidized frying oil (OFO) can activate PPARalpha and up-regulate its target genes, a feeding experiment and a transactivation experiment were conducted. Based on a 2 x 2 factorial design, four groups of Sprague-Dawley male weanling rats were fed diets containing either high (20 g/100 g, HO and HF) or low (5 g/100 g, LO and LF) levels of oxidized frying soybean oil (HO and LO) or fresh soybean oil (HF and LF) for 6 wk. The OFO sample was prepared by frying wheat dough sheets in soybean oil at 205 +/- 5 degrees C for 24 h. OFO dose dependently and significantly increased (P < 0.05) mRNA of acyl-CoA oxidase (ACO) and cytochrome P(450) 4A1(CYP4A1) in liver of rats. Dietary OFO also dose dependently increased liver microsomal CYP4A protein (P < 0.05). The activity of hepatic ACO of the HO group was sixfold that of the HF group (P < 0.05). Plasma total lipids, liver triglycerides, cholesterol and total lipids were reduced in rats fed the LO and HO diets (P < 0.05). Through the ligand binding domain of PPARalpha, the hydrolyzed OFO enhanced the expression of alkaline phosphatase (ALP) reporter gene to a significantly greater extent (P < 0.05) than the hydrolyzed fresh soybean oil in a transactivation assay using a clone of CHO K1 cells stably expressing Gal4-PPARalpha chimeric receptor and UAS4-ALP reporter. The results support our hypothesis that dietary OFO, by activating PPARalpha, up-regulates the expression of PPARalpha downstream genes and alters lipid metabolism in rats.

Hydrogenation of vegetable oils using mixtures of supercritical carbon dioxide and hydrogen

Abstract: Hydrogenation of vegetable oils under supercritical conditions can involve a homogeneous one-phase system, or alternatively two supercritical components in the presence of a condensed phase consisting of oil and a solid catalyst. The former operation is usually conducted in flow reactors while the latter mode is more amenable to stirred, batch-reactor technology. Although many advantages have been cited for the one-phase hydrogenation of oils or oleochemicals using supercritical carbon dioxide or propane, its ultimate productivity is limited by the oil solubility in the supercritical fluid phase as well as unconventional conditions that affect the hydrogenation. In this study, a dead-end reactor has been utilized in conjunction with a head-space consisting of either a binary fluid phase consisting of varying amounts of carbon dioxide mixed with hydrogen or neat hydrogen for comparison purposes. Reaction pressures up to 2000 psi and temperatures in the range of 120–140°C have been utilized with a conventional nickel catalyst to hydrogenate soybean oil. Depending on the chosen reaction conditions, a wide variety of end products can be produced having different iodine values, percentage trans fatty acid content, and dropping points or solid fat indices. Although addition of carbon dioxide to the fluid phase containing hydrogen retards the overall reaction rate in most of the studied cases, the majority of products have low trans fatty acid content, consistent with a nonselective mode of hydrogenation.

A Pilot Plant to Produce Biodiesel from High Free Fatty Acid Feedstocks

Abstract: Biodiesel is an alternative diesel fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Currently, most biodiesel is made from soybean oil, methanol, and an alkaline catalyst. However, there are large amounts of fats and oils that are unsuitable for human consumption that could be converted to biodiesel at lower cost. The problem with processing these waste oils is that they often contain large amounts of free fatty acids that cannot be converted to biodiesel using an alkaline catalyst. These free fatty acids react with the alkaline catalyst to produce soaps that inhibit the separation of the biodiesel, glycerin, and wash water. Previous research has developed a process for pretreating these high free fatty acid feedstocks using acid catalysts which do not form soaps. The objective of this study was to construct a pilot plant to produce biodiesel from a wide variety of feedstocks including those with high free fatty acids. A 190-liter batch pilot plant has been built which can process high free fatty acid feedstocks using an acid-catalyzed pretreatment followed by an alkaline-catalyzed transesterification. Case studies of pilot plant-scale production of biodiesel from soybean oil, yellow grease with 9% free fatty acids, and brown grease with 40% free fatty acids are presented. The effect of varying the reaction parameters is discussed and the separation and washing processes are described. Estimates of the fuel cost using different feedstocks are also provided.

Adaptation of the AOCS Official Method for Measuring Hydroperoxides from Small-Scale Oil Samples

Abstract: An adaptation of the American Oil Chemists' Society Official Method Cd 8–53 for determining peroxides in fats and oils using a 0.5-g sample is described. Comparisons of the Official Method and the small-scale method were performed by analyzing soybean oil samples spiked with t-butyl hydroperoxide and autoxidized soybean oil samples. A linear relationship between the Official Method and the small-scale method was obtained with an R2 of 0.998. The small-scale method is sensitive, precise, and suitable for small sample sizes and uses only about 10% of the chemicals necessary for the Official Method.

New soybean oil‐styrene‐divinylbenzene thermosetting copolymers. III. Tensile stress–strain behavior

Abstract: The tensile stress–strain behavior and fracture properties of some new soybean oil based polymeric materials were investigated at room temperature. These materials were prepared by the cationic copolymerization of regular soybean oil, low saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and the diene comonomers divinylbenzene, norbornadiene, or dicyclopentadiene in a process initiated by boron trifluoride diethyl etherate (BF3 · OEt2) or related modified initiators. These new polymeric materials exhibited tensile stress–strain behavior ranging from soft rubbers through ductile to relatively brittle plastics. The Young's moduli of these polymers varied from 3 to 615 MPa, the ultimate tensile strengths varied from 0.3 to 21 MPa, and the elongation at break varied from 1.6 to 300%. These properties are obviously related to their crosslink densities. The conjugated LoSatSoy oil polymers had higher mechanical properties than the corresponding LoSatSoy oil and regular soybean oil polymers with the same stoichiometry. Some conjugated LoSatSoy oil polymers with appropriate stoichiometries showed yielding behavior in the tensile test process. A variety of new polymer materials can thus be prepared by varying the stoichiometry, the type of soybean oil, and the crosslinking agent. These soybean oil based polymers possessed mechanical properties comparable to those of commercially available rubbery materials and conventional plastics and thus may serve as replacements in many applications. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 60–77, 2001

Antioxidants and total peroxyl radical-trapping ability of olive and seed oils.

Abstract: The presence of the oxidized and reduced forms of ubiquinones Q(9) and Q(10) was determined in commercial extra virgin olive and seed oils, where the amounts of alpha- and gamma-tocopherols and beta-carotene were also quantitated. Very high concentrations of ubiquinones were found in soybean and corn oils. Furthermore, the total antioxidant capability of each oil was evaluated by measuring total radical-trapping antioxidant parameters (TRAP) in tert-butyl alcohol and using egg lecithin as the oxidizable substrate. These values decreased in the order sunflower > corn > peanut > olive; the highest TRAP, which was found in sunflower oil, was related to the very high amount of alpha-tocopherol. Olive oil, because of the low content of alpha-tocopherol, exhibited a TRAP value approximately one-third that of sunflower oil. TRAP values of corn and soybean oils, in which low amounts of alpha-tocopherol but very high contents of gamma-tocopherol and reduced ubiquinones were present, were intermediate. gamma-Tocopherol exhibited a poor ability of trapping peroxyl radicals in tert-butyl alcohol. This behavior was probably due to the effects of the solvent on the rate of hydrogen abstraction from this phenol.

Simultaneous determination of lipophilic aldehydes by high‐performance liquid chromatography in vegetable oil

Abstract: A very sensitive high-performance liquid chromatography (HPLC) method was developed for the simultaneous separation and measurement of nonpolar and polar lipophilic secondary lipid peroxidation products in vegetable oil. Seventeen nonpolar and 13 polar lipophilic aldehydes and related carbonyl compounds, derived from thermally oxidized soybean oil as 2,4-dinitrophenyl hydrazones, were separated simultaneously by reversed-phase HPLC. Detection limit for the individual compounds is 1 ng. Thirteen of the nonpolar carbonyl compounds were identified as: butanal, 2-butanone, pentanal, 2-pentanone, hexenal, hexanal, 2,4-heptadienal, 2-heptenal, octanal, 2-nonenal, 2,4-decadienal, decanal, and undecanal. Three of the polar carbonyl compounds were identified as: 4-hydroxy-2-hexenal, 4-hydroxy-2-octenal, and 4-hydroxy-2-nonenal. The detection of the toxic 4-hydroxy-2-nonenal, a major compound, and 4-hydroxy-2-hexenal, a minor compound, in heated soybean oil is of particular importance because these toxic compounds have been shown to be absorbed from the diet.

Influence of Cultivar and Fruit Ripening on Olive (Olea europaea) Fruit Protein Content, Composition, and Antioxidant Activity

Abstract: Proteins of olive fruit mesocarp are not very well-known at present. However, they have been shown to pass, at least partially, to the olive oil during its elaboration and therefore might be contributing to some of the special characteristics of this vegetable oil. In this study, protein content and composition were determined in olive fruits, cv. Arbequina and Picual, at three stages of ripening: green, spotted, and purple. Mesocarp proteins constituted 1.3-1.8% of the dry weight of the olive fruit, and cultivar and fruit ripening did not produce important changes in mesocarp protein content or composition. In addition, this composition was also similar to the amino acid composition of a 4.6-kDa polypeptide, which is the major protein component of olive oils and of oil bodies of olive fruit mesocarp, suggesting that this polypeptide is likely to be a major component of mesocarp proteins. There was, also, a relationship between the oil content of the olive fruit and the protein content determined, suggesting a stabilizing function of these proteins in the oil bodies of the olive fruit, analogously to the role suggested for oleosins. This stabilizing function does not seem to be extended to olive oils because when the polypeptides isolated were added at 20 ppm to soybean oil, the stability of the oil increased only slightly, suggesting that if these compounds play some role in the stability of the oils, this should be mostly a consequence of the possible interactions among these protein components and other olive oil antioxidant constituents.