bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal tocopherol concentrations to inhibit soybean oil oxidation
Authors: Evans J. C. , Kodali D. R. , Addis P. B. 
Published: November 2006

AbstractThe optimal concentration for tocopherols to inhibit soybean oil oxidation was determined for individual tocopherols (α‐, γ‐, and δ‐tocopherol) and for the natural soybean oil tocopherol mixture (tocopherol ratio of 1∶13∶5 for α‐, γ‐, and δ‐tocopherol, respectively). The concentration of the individual tocopherols influenced oil oxidation rates, and the optimal concentrations were unique for each tocopherol. For example, the optimal concentrations for α‐tocopherol and γ‐tocopherol were ∼100 and ∼300 ppm, respectively, whereas δ‐tocopherol did not exhibit a distinct concentration optimum at the levels studied (P<0.05). The optimal concentration for the natural tocopherol mixture ranged between 340 and 660 ppm tocopherols (P<0.05). The antioxidant activity of the tocopherols diminished when the tocopherol levels exceeded their optimal concentrations. Above their optimal concentrations, the individual tocopherols and the tocopherol mixture exhibited prooxidation behavior that was more pronounced with increasing temperature from 40 to 60°C (P<0.05). A comparison of the antioxidant activity of the individual tocopherols at their optimal concentrations revealed that α‐tocopherol (∼100 ppm) was 3–5 times more potent than γ‐tocopherol (∼300 ppm) and 16–32 times more potent than δ‐tocopherol (∼1900 ppm).
Friction and adsorption properties of normal and high‐oleic soybean oils
Authors: Biresaw G. , Adhvaryu A. , Erhan S. Z. , Carriere C. J. 
Published: November 2006

AbstractThe steel/steel boundary friction properties of soybean oil (SBO) and high‐oleic soybean oil (HOSBO) are compared. HOSBO is significantly more saturated than SBO and more oxidatively stable. Changes in degree of unsaturation affect lateral interactions of adsorbate molecules, which in turn affects their adsorption and, hence, their boundary lubrication properties. To investigate this possibility, the free energies of adsorption (ΔGads) of SBO, HOSBO, and methyl laurate (ML) were determined from the analysis of friction‐derived adsorption isotherms using the Langmuir and Temkin adsorption models. The results showed a stronger adsorption for the vegetable oils than for ML, an indication of multiple interactions between the ester groups of the triglycerides and the steel surface. The result also showed no difference in the ΔGads values of SBO and HOSBO obtained using either the Langmuir or Temkin models. This was interpreted as an indication of the lack of appreciable net lateral interaction between triglyceride adsorbates.
Solvent‐based fatty alcohol synthesis using supercritical butane: Flowsheet analysis and process design
Authors: Brands D. S. , Pontzen K. , Poels E. K. , Dimian A. C. , Bliek A. 
Published: November 2006

AbstractThe liquid‐phase hydrogenolysis of fatty esters to fatty alcohols is an important step in the industrial manufacture of surfactants and detergents. High operating pressures are necessary, due to the low solubility of hydrogen in fatty esters feeds. In principle, these high operating pressures might be overcome by use of a suitable solvent, but only at the expense of large solvent recycle and cumbersome product‐solvent separation. The employ of supercritical solvents may resolve these drawbacks, as an elegant solvent‐product separation is possible by reverting to the subcritical regime. In the present work the hydrogenolysis of methyl palmitate in supercritical butane is investigated by simulation. Operating conditions are analyzed on the basis of vapor liquid equilibrium data and chemical equilibrium considerations. Separation and recycle problems are evaluated and discussed on the basis of a flowsheet analysis. It is demonstrated that an efficient hydrogenolysis process may be developed by using supercritical butane as solvent. A moderate operating pressure (9 MPa) and temperature (470 K) lead to high conversion levels and high product purity. A hydrogen to ester molar ratio of 4∶1 in the feed is achievable, which compares favorably to existing liquid‐and gas‐phase processes, and allows recycle streams to be reduced.
Effects of physical refining on contents of waxes and fatty alcohols of refined olive oil
Authors: Tubaileh Rana M. , Garrido‐Fernández Antonio , Victoria Ruiz‐Méndez M. , León‐Camacho Manuel , Graciani‐Constante Enrique 
Published: November 2006

AbstractChanges in the contents of waxes and fatty alcohols during deodorization/physical refining of bleached olive oil were studied. Experiments were carried out with 1.85% acidity oil, which was physically refined in a discontinuous deodorizer of 250‐kg maximum capacity using nitrogen as stripping gas instead of steam. The variables studied were load and temperature of oil in the deodorizer as well as N2 flow. Analyses of waxes and alcohols were carried out at different operation times. The maximum content of wax was always observed when the oil reached the deodorization temperature. The variation in the wax content depended on temperature and N2 flow. Wax decomposition started and continued during the operating time, and a progressive decrease, which was pronounced between 3 and 4 h, was observed. Small changes in waxes were observed between 4 and 5 h. Total content of fatty alcohols diminished throughout the operating time, and changes did not depend on the variables studied.
Analysis of free and esterified sterols in vegetable oils
Authors: Verleyen T. , Forcades M. , Verhe R. , Dewettinck K. , Huyghebaert A. , De Greyt W. 
Published: November 2006

AbstractIn vegetable oils, phytosterols occur as free sterols or as steryl esters. Few analytical methods report the quantification of esterified and free sterols in vegetable oils. In this study, esterified and free sterols were separated by silica gel column chromatography upon elution with n‐hexane/ethyl acetate (90∶10 vol/vol) followed by n‐hexane/diethyl ether/ethanol (25∶25∶50 by vol). Both fractions were saponified separately and the phytosterol content was quantified by GC. The analytical method for the analysis of esterified and free sterols had a relative standard deviation of 1.16% and an accuracy of 93.6–94.1%, which was comparable to the reference method for the total sterol analysis. A large variation in the content and distribution of the sterol fraction between different vegetable oils can be observed. Corn and rapeseed oils were very rich in phytosterols, which mainly occurred as steryl esters (56–60%), whereas the majority of the other vegetable oils (soybean, sunflower, palm oil, etc.) contained a much lower esterified sterol content (25–40%). No difference in the relative proportion of the individual sterols among crude and refined vegetable oils was observed.
Effect of relative humidity on the oxidative and physical stability of encapsulated milk fat
Authors: Hardas N. , Danvirivakul S. , Foley J. L. , Nawar W. W. , Chinachoti P. 
Published: November 2006

AbstractMilk fat was used in this work as a model to study the effects of humidity and physical properties on lipid oxidation. Although milk fat is considered a relatively stable fat because of its low content of unsaturated FA, it can oxidize significantly under certain conditions, as observed, for example, in the case, of dairy‐based powders. Humidity and physical properties have a profound influence on the oxidative stability of powders, containing fat, and these factors affect the surface and encapsulated fractions of the fat differently. To examine these effects, encapsulated milk fat powders were stored under conditions of controlled relative humidity. Oxidation of the encapsulated fat as assessed by measurements of PV, losses of FA, and hexanal production increased, with increasing relative humidity (RH). At higher RH, moisture penetrates into the hydrophilic wall, interacting with and plasticizing the components, thereby making them less effective as moisture and oxygen barriers. Total oxidation of the powders was strongly influenced by the extent of oxidation in the encapsulated fraction (>98% of total lipids) although the surface fat fraction was oxidized more rapidly. Better protection against oxidation was obtained when fats were encapsulated and stored at 14 and 44% RH than at 52% RH.
Conjugated linoleic acid production from linoleic acid by lactic acid bacteria
Authors: Kishino Shigenobu , Ogawa Jun , Omura Yoriko , Matsumura Kenji , Shimizu Sakayu 
Published: November 2006

AbstractAfter screening 14 genera of lactic acid bacteria, Lactobacillus plantarum AKU 1009a was selected as a potential strain for CLA production from linoleic acid. Washed cells of L. plantarum with high levels of CLA production were obtained by cultivation in a nutrient medium with 0.06% (wt/vol) linoleic acid (cis‐9,cis‐12‐octadecadienoic acid). Under the optimal reaction conditions with the free form of linoleic acid as the substrate, washed cells of L. plantarum produced 40 mg CLA/mL reaction mixture (33% molar yield) from 12% (wt/vol) linoleic acid in 108 h. The resulting CLA was a mixture of two CLA isomers, cis‐9,trans‐11 (or trans‐9,cis‐11)‐octadecadienoic acid (CLA1, 38% of total CLA) and trans‐9,trans‐11‐octadecadienoic acid (CLA2, 62% of total CLA), and accounted for 50% of the total FA obtained. A higher yield (80% molar yield to linoleic acid) was attained with 2.6% (wt/vol) linoleic acid as the substrate in 96 h, resulting in CLA production of 20 mg/mL reaction mixture [consisting of CLA1 (2%) and CLA2 (98%)] and accounting for 80% of total FA obtained. Most of the CLA produced was associated with the cells (ca. 380 mg CLA/g dry cells), mainly as FFA.
Epoxidation of soybean oil by the methyltrioxorhenium‐CH2Cl2/H2O2 catalytic biphasic system
Authors: Gerbase Annelise E. , Gregório José R. , Martinelli Márcia , Brasil Márcia C. , Mendes Ana N. F. 
Published: November 2006

AbstractWe studied the methyltrioxorhenium (MTO)‐CH2Cl2/H2O2 biphasic system for epoxidizing soybean oil. The reactions were optimized (reactant ratio, time, and temperature), which resulted in a better performance (higher conversion and selectivity) than those described in the literature. Total doublebond conversion and 95% selectivity were obtained in 2 h at room temperature. Furthermore, it was possible to reach desired epoxidation degrees by changing the oxidant and MTO amounts. The rhenium‐epoxidized soybean oil remained stable in the absence of stabilizers for up to 30 d when stored at mild conditions.
Production of alkyl ester as biodiesel from fractionated lard and restaurant grease
Authors: Lee Ki‐Teak , Foglia Thomas A. , Chang Kyu‐Seob 
Published: November 2006

AbstractMethyl or ethyl esters were produced from lard and restaurant grease by lipase‐ or base‐catalyzed reactions. Before esterifying, some renewable substrates (lard and restaurant grease) should be manipulated through acetone fractionation or on a chromatography column packed with an adsorbent to obtain maximal reaction rate. Because lipase activity was hindered by excess amounts (more than 1 mol) of methanol, each 1 M methanol was added sequentially after 24 h of reaction. Through a three‐step reaction, 74% conversion to tallow‐methyl ester was obtained. However, a porous substance, such as silica gel, improved the conversion when more than 1 M methanol was used as reaction substrate. When a 1∶3 (fractionated lard/methanol, mole ratio) substrate was used, the conversion rates (i.e., extent of conversion) were 2.7 (24 h) and 2.8% (48 h). However, with 10% silica gel in the reaction mixture, the conversion rates increased to 25 and 58%, respectively. Regenerated restaurant grease (FFA removed through column chromatography) was further converted to esters by alkali‐catalyzed methanolysis. After 24 h of reaction, 96% conversion was obtained, while only 25% conversion was observed from crude grease. Alkyl esters produced in this study could be used for fuels, potentially as biodiesel.
Plasticization of soy protein polymer by polyol‐based plasticizers
Authors: Mo Xiaoqun , Sun Xiuzhi 
Published: November 2006

AbstractSoy protein isolate (SPI) was mixed with four polyol‐based plasticizers and molded into plastics using a hot press. The plasticized SPI powder was evaluated for denaturation temperatures and denaturation enthalpies. The SPI plastics were studied for mechanical properties, glass transition temperatures, storage modulus, morphology, and water absorption. Thermal properties of the SPI plastics with propylene glycol were depressed to the largest degree, and the plastics with glycerol showed the largest strain at break, whereas plastics with 1,3‐butanediol gave the highest tensile strength. The morphology of the fractured surface on the SPI plastics changed from brittle fracture for the unplasticized SPI to ductile fracture for the plasticized SPI. Water absorption of all the plasticized SPI plastics was lower than that of the unplasticized SPI plastics.
Effect of gallic acid on the aroma constituents of soymilk and soy protein isolates
Authors: Boatright W. L. 
Published: November 2006

AbstractVolatile compounds from soymilk were analyzed by gas chromatography/olfactometry/mass spectrometry (GCO/MS) with direct injection of various volumes of static headspaces. The most powerful odorants, determined by the minimum headspace volume required to detect by olfactometry, were (i) hexanal, (ii) acetaldehyde, (iii) methanethiol, (iv) dimethyl trisulfide (DMTS), and (v) 2‐pentyl furan. Analyses of soymilk prepared with the addition of 100 ppm gallic acid revealed that the only two detectable odorants were hexanal and acetaldehyde. Sensory analyses of the soymilk treated with 100 ppm gallic acid produced a significantly lower score (P=0.0006) for overall odor intensity compared with the control soymilk. Aqueous slurries of soy protein isolates (SPI) prepared with the addition of 100 ppm gallic acid also had lower odor intensities than the control SPI (P<0.0001). GCO/MS analyses of headspace volatiles revealed that the gallic acid treatment had removed all detectable levels of methanethiol and DMTS while having no significant effect on the level of hexanal (P=0.81).
Lipase‐catalyzed acidolysis of perilla oil with caprylic acid to produce structured lipids
Authors: Kim In‐Hwan , Kim Hakryul , Lee Ki‐Teak , Chung Soo‐Hyun , Ko Soon‐Nam 
Published: November 2006

AbstractStructured lipids were synthesized by acidolysis of perilla oil and caprylic acid using two lipases, Lipozyme RM IM from Rhizomucor miehei and Lipozyme TL IM from Thermomyces lanuginosa. Effects of molar ratio, reaction time, reaction temperature, enzyme load, and solvent content on acidolysis reactions were studied. The solvent content ranged from 0.0 (solvent‐free) to 85.3%. The results showed that the incorporation increased in parallel with solvent content to 49.0% with Lipozyme RM IM and to 63.8% with Lipozyme TL IM. After 24 h incubation in n‐hexane, caprylic acids were incorporated to 48.5 mol% with Lipozyme RM IM and to 51.4 mol% with Lipozyme TL IM, respectively, whereas linolenic acid content was reduced from 61.4 to 31.5 mol% with Lipozyme RM IM and to 28.4 mol% with Lipozyme TL IM, respectively. Lipozyme TL IM showed a higher acyl migration rate than Lipozyme RM IM when acidolysis was performed in the reaction system containing n‐hexane as a solvent, whereas the difference in acyl migration between the two lipases in the solvent‐free system was negligible.
Impact of extraction method on yield of lipid oxidation products from oxidized and unoxidized walnuts
Authors: Crowe Tammy D. , Crowe Troy W. , Johnson Lawrence A. , White Pamela J. 
Published: November 2006

AbstractThe objective of this study was to measure and compare differences in oxidized products of oil extracted from unoxidized and oxidized walnuts using five different extraction methods: (i) mechanical pressing, or solvent extraction with (ii) hexane, (iii) methylene chloride, (iv) chloroform/methanol, or (v) supercritical carbon dioxide (SC−CO2). Of the extraction methods evaluated, only chloroform/methanol and methylene chloride provided reasonable results for all parameters measured (total lipid yield, FA profile, PV, conjugated dienes, FFA content, and volatile content); however, chloroform/methanol extracted significantly greater levels of volatile compounds. The SC−CO2 extraction with purified gas was simple and accurate for all data except collection of volatile compounds, as these materials are lost during the lipid extraction. Pressing was neither quantitative nor qualitative, and hexane extraction retrieved significantly lower levels of volatiles than the other methods, except for SC−CO2.
Effects of pH and ferric ions on the antioxidant activity of olive polyphenols in oil‐in‐water emulsions
Authors: Paiva‐Martins Fátima , Gordon Michael H. 
Published: November 2006

AbstractThe effects of four phenolic compounds occurring in olives and virgin olive oil, namely, oleuropein, hydroxytyrosol, 3,4‐dihydroxyphenylethanol‐elenolic acid (3,4‐DHPEA‐EA) and 3,4‐dihydroxyphenylethanol‐elenolic acid dialdehyde (3,4‐DHPEA‐EDA), on the oxidative stability of stripped olive oil‐in‐water emulsions were studied at three pH values in the presence or absence of ferric chloride at 60°C. In the stability test, the addition of phenolic compounds in emulsions at pH 5.5 significantly extended the induction time of lipid oxidation, and the activities in decreasing order were 3,4‐DHPEA‐EA> 3,4‐DHPEA‐EDA>hydroxytyrosol>α‐tocopherol∼oleuropein ≫control. The effect of concentration, iron, and pH on the antioxidant activity of the phenolic compounds in stripped olive oil‐in‐water emulsions was analyzed by response surface methodology. Oleuropein and hydroxytyrosol enhanced the prooxidant effect of ferric chloride at pH 3.5 and pH 5.5 but not at pH 7.4. The 3,4‐DHPEA‐EDA reduced the prooxidant effect of ferric chloride at pH 5.5 and pH 7.4, but at pH 3.5 prooxidant effects were evident at higher phenol concentration. The 3,4‐DHPEA‐EA reduced the prooxidant effect of ferric ions at all pH values tested. Differences in activity of the phenols may be explained by consideration of their free radical scavenging activity and ferric reducing capacity.
Changes in the main components and quality indices of virgin olive oil during oxidation
Authors: Gutiérrez F. , Villafranca M. J. , Castellano J. M. 
Published: November 2006

AbstractThis work reports on changes in the major and minor components of virgin olive oil during oxidation, details modifications found in the standardized quality indices, and analyzes the most significant relationships between the components of the oil and its oxidative stability. During the induction period or slow phase of oxidation, polyphenols, tocopherols, and pigments undergo the most important alterations. Other compounds, such as FA or volatiles, suffer significant modifications only during the rapid or exponential phase of oxidation when the natural antioxidant systems fall to minimal values. Among the quality indices, PV and the specific extinction coefficients K232 and K270 increase markedly from the earliest stages of oxidation, whereas titratable acidity does not change appreciably during the induction period. The evolution of the different compounds and parameters analyzed suggests that the tocopherol and orthodiphenol contents are the best indices to determine the average life of the oils.
Exhaust emissions and health effects of particulate matter from agricultural tractors operating on rapeseed oil methyl ester
Authors: Krahl Jürgen , Bünger Jürgen , Schröder Olaf , Munack Axel , Knothe Gerhard 
Published: November 2006

AbstractExhaust emissions and their effects on the environment and human health, such as mutagenicity of particulate matter (PM) and ozone‐forming potential, must be considered when using an alternative fuel. In the present work, a test engine and two agricultural tractors ran on rapeseed oil methyl ester (biodiesel) or conventional diesel fuel as well as blends thereof. The objective was to detect any disproportionately positive or negative effects depending on blend levels, because conventional diesel fuel and biodiesel can be blended in every ratio. Generally, emissions of regulated compounds changed linearly with the blend level. The known positive and negative effects of biodiesel varied accordingly. Overall, no optimal blend was found. Increasing biodiesel content of the fuel caused a linear increase in benzene emissions in the agricultural five‐mode engine test, an effect that may be explained from previous studies on precombustion chemistry. In using the test engine, it was found that PM from biodiesel significantly reduced mutagenic potential compared with that from diesel fuel, although in this work PM masses were found to be reproducibly higher for biodiesel from rapeseed oil compared with conventional diesel fuel. Ozone precursors increased 10–30% when using biodiesel compared with conventional diesel fuel. Emissions of aldehydes and alkenes are mainly responsible for this effect. N2O emissions increased when using a catalytic converter.
Dynamic mechanical and thermal behavior of epoxy resins based on soybean oil
Authors: Gerbase Annelise E. , Petzhold Cesar L. , Costa Ana Paula O. 
Published: November 2006

AbstractMechanical and thermal properties of materials prepared by curing epoxidized soybean oil with various cyclic acid anhydrides in the presence of tertiary amines were investigated by dynamic mechanical thermal analysis and thermogravimetry. All samples presented thermoset material characteristics that were dependent upon the type of anhydride, the anhydride/epoxy molar ratio, and epoxy group content. The thermosets obtained from anhydrides with rigid structures as such phthalic, maleic, and hexahydrophthalic showed higher glass transition temperatures (Tg) and cross‐linking densities. As expected, the Tg decreased as the anhydride/epoxy ratio decreased. The influence of the degree of epoxidation of soybean oil on the mechanical properties and Tg was also investigated. It was found that the higher the epoxy group amount, the higher the Tg and hardness. Cured resins exhibited thermal stability up to 300°C, except for those prepared with dodecenyl succinic anhydride, which began to decompose at lower temperature. They presented excellent chemical resistance when immersed in 1% wt/vol NaOH and 3% wt/vol H2SO4 solutions but poor chemical resistance in the presence of organic solvents.
Extraction of oil from ground corn using ethanol
Authors: Kwiatkowski J. R. , Cheryan M. 
Published: November 2006

AbstractCorn oil was extracted from whole ground corn using ethanol as the solvent. The yield of oil was measured as a function of temperature, time of extraction, solvent‐to‐solids ratio, and ethanol concentration. Optimal conditions were a solvent‐to‐solids ratio of 4 mL/g corn, an ethanol concentration of 100%, 30 min of extraction time, and a temperature of 50°C. Under these conditions, a single batch extraction yielded ≈3.3 g oil/100 g corn, equivalent to 70% extraction efficiency. A three‐stage extraction, where the same corn was exposed to fresh ethanol, resulted in a yield of ≈4.5 g/100 g corn (2.5 lb/bu of corn), equivalent to 93% recovery of the oil in corn. When anhydrous ethanol was used to repeatedly extract fresh corn, moisture was absorbed linearly by ethanol from the corn in successive stages, which, in turn, decreased oil yield and increased nonoil components in the extract.