bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of geometrical isomerization of unsaturated FA in soybean oil
Authors: Gerčar Nadja , Šmidovnik Andrej
Published: November 2006

Laboratory treatment of soybean oil were carried out at the following conditions: atmospheric pressure in the presence of air or nitrogen at different temperatures ranging from 160 to 250°C for 12 to 72 h. These conditions were used to study geometric isomerization of cis,cis‐linoleic and cis,cis,cis‐linolenic acid in the presence or in the absence of oxidative degradation reactions. Based on these experiments, a model of consecutive, parallel reactions was developed to describe the reaction steps occurring in the soybean oil during heating at constant temperature. For both cis,cis‐linoleic and cis,cis,cis‐linolenic acid, the reaction of formation isomers followed a first‐order reaction, and the rate constant of isomerization varied according to the Arrhenius law. The isomerization rate constant for linoleic acid was 9.57×10−3±0.50 h−1 in the presence of oxygen and 7.39×10−3±0.39 h−1 in its absence, and the isomerization rate constant for linolenic acid was 1.18×10−1±0.10 h−1 in the presence of oxygen and 0.87×10−1±0.07 h−1 in its absence (all obtained at 250°C).
The role of water in the oxidation process of extra virgin olive oils
Authors: Ambrosone L. , Angelico R. , Cinelli G. , Di Lorenzo V. , Ceglie A.
Published: November 2006

Different emulsifying techniques were used to study the influence of water on the oxidative degradation of extra virgin olive oil. The emulsions of water/extra virgin olive oil, oxidized with O2, UV radiation, and Air, were prepared by dispersing water under different conditions. Oil oxidation, monitored by measuring the PV and polyphenolic content, was greater for emulsions obtained with low dispersing power. A linear model was used to correlate the PV and the polyphenolic content with dispersing energy. An important result was that the dispersed water exerted a positive antioxidant effect on the oil.
Rapid MS method for analysis of cocoa butter TAG
Authors: Kurvinen J. ‐P. , Sjövall O. , Tahvonen R. , Anklam E. , Kallio H.
Published: November 2006

Ammonia negative ion CI‐MS was applied to analyze the M.W. distribution and regioisomeric structure of TAG in cocoa butter and in cocoa butter equivalents. The M.W. distribution results obtained for a reference cocoa butter were consistent with corresponding results obtained in an intercomparison study by chromatographic methods. Minor but statistically significant differences were observed when proportions of the three major M.W. species (52∶1, 54∶1, and 50∶1; acyl carbon number/number of double bonds) in a mixture of nine cocoa butters and in mixtures containing 10 or 20% (w/w) of specific cocoa butter equivalents were compared. Tandem MS was used to determine the regioisomeric structure of the three major TAG M.W. species in cocoa butter and in cocoa butter equivalents. The regioisomeric structure in cocoa butter and in all the equivalents analyzed were nearly identical, oleic acid being located primarily in the sn‐2 position. These results cannot be exploited in detecting added foreign fats in this case. However, the present study shows that useful TAG composition data, which may be used to detect foreign fats in cocoa butter by applying chemometric data evaluation, can be obtained by MS in a significantly shorter time compared to chromatographic methods.
Ozonization of phenols from Anacardium occidentale (cashew)
Authors: Graham Madeline B. , Tyman H. P.
Published: November 2006

The phenolic lipid components cardanol and cardol, obtained from heat‐processed technical cashew nutshell liquid from Anacardium occidentale, and anacardic acid from the natural product, each containing monoene, diene, and triene constituents, were ozonized. The ozonides were reduced chemically and catalytically to give 8‐(3‐hydroxyphenyl)octanal, 8‐(3,5‐dihydroxyphenyl)octanal, and 8‐(3‐hydroxy‐2‐carboxyphenyl)octanal, respectively, together with formaldehyde, malondialdehyde, butanal, and heptanal in each case. Reduction of the 8‐(3‐hydroxyphenyl)octanal, which was synthesized from 3‐benzyloxybenzaldehyde, gave 3‐octylphenol. Oxidation of the aldehyde with potassium permanganate gave 8‐(3‐hydroxyphenyl)octanoic acid, and reduction with sodium borohydride yielded 8‐(3‐hydroxyphenyl)octanol. For comparison, the trans‐diols of cardanol were prepared by treatment of cardanol with peroxyformic acid and cleaved by periodate oxidation to give an alternative route to 8‐(3‐hydroxyphenyl)octanal but in lower yield. Likewise, the cis‐diols were obtained with potassium permanganate and cleaved without isolation to give the same product in lower yield compared with ozonization.
Abilities of some antioxidants to stabilize soybean oil in industrial use conditions
Authors: Ruger Christopher W. , Klinker Eric J. , Hammond Earl G.
Published: November 2006

Antioxidants, chelators, and alcohols were screened at 0.01 and 1.28% by weight for their ability to delay viscosity increase in soybean oil in the presence of metallic colloidal copper and iron at 105°C with air flowing through the sample. Most substances did not significantly enhance the effect of the natural tocopherols in the soybean oil at 0.01%. A few substances were mildly prooxidant, and a few delayed the increase in viscosity significantly. TBHQ at 0.01% was the best antioxidant of those tested. At 1.28% ascorbyl palmitate, BHT, hydroquinone, and TBHQ increased the stability significantly. Again, TBHQ was the most effective. As measured by viscosity increase to 150 CP, TBHQ increased stability about five times over that of soybean oil controls.
Rheological and thermal properties of soybean oils with modified FA compositions
Authors: Wang Tong , Briggs Jenni L.
Published: November 2006

Rheological and thermal properties of five soybean oils with modified FA compositions were studied. Viscosity decreased with increasing temperature at different rates for the different oils. Oil with a high‐oleic acid content had higher viscosity and a greater rate of change than did oils with typical FA compositions, oil with low‐saturated FA or low‐linolenic acid content, or oil from lipoxygenase‐free soybeans. The melting and crystallization behaviors of the oils were examined using DSC. The high‐oleic acid oil and the oil with low‐saturated FA content had different DSC profiles compared with the other oils. Specific heat capacities of oils were estimated using a mathematical model; the high‐oleic acid oil had a higher specific heat value, and the low‐saturated FA oil had a lower value than did the other oils.
Effect of water washing on the reduction of surface total lipids and FFA on milled rice
Authors: Monsoor M. A. , Proctor A.
Published: November 2006

A simple method for removing total lipids from the rice surface by water washing is described for brewing operations, where small FFA levels can have a considerable effect on end‐product flavor quality. Commercially milled (first‐, second‐, and third‐break) rice was washed with deionized water with constant stirring for 5 and 10 min. About 60 to 80% of total surface lipids were removed by water washing, with a reduction of FFA and conjugated dienes (CD) relative to unwashed control samples. The total surface FFA content of first‐, second‐, and third‐break milled rice was reduced by more than 50% of the original value by washing. Increases in FFA and CD in washed rice after 7 d of storage at 37°C and 70% RH were much lower than those of unwashed controls, in which FFA and CD development was considerably greater and reached brewing quality. Water washing may be a practical means of reducing off‐flavor development in milled rice.
Solubility in supercritical carbon dioxide of the predominant carotenes of tomato skin
Authors: Gómez‐Prieto M. S. , Caja M. M. , Santa‐María G.
Published: November 2006

Solubilities in supercritical carbon dioxide of the predominant carotenes in tomato skin were measured. The use of a polymeric C30 RP‐HPLC column to analyze the tomato extract made it possible to separate several geometric isomers from each carotene extracted. The Chrastil model was used to assign a solubility equation to each extracted carotene. Different solubility behaviors in supercritical carbon dioxide were shown by carotenes depending on their nature and configuration. The most soluble carotene was all‐trans‐phytoene and the least soluble was all‐trans‐lycopene. Significant differences in solubility were observed between the trans and cis isomers of lycopene. The results indicate that a fractionation of the tomato skin carotenes can be achieved by using supercritical CO2 extraction.
Retardation of volatile aldehyde formation in the exhaust of frying oil by heating under low oxygen atmospheres
Authors: Fujisaki Mariko , Endo Yasushi , Fujimoto Kenshiro
Published: November 2006

Volatile aldehydes were generated in the exhaust of high‐oleic safflower oil during heating at 180°C by spraying water into atmospheres with four levels of oxygen concentrations (2, 4, 10, and 20%). These aldehydes were quantitatively analyzed by HPLC after the conversion to 2,4‐dinitrophenyl hydrazones. Ten alkanals (C2 through C10), eight 2‐alkenals (C3 through C10) and three 2,4‐alkadienals (C7, C9, and C10) were found. These aldehyde levels were found to be positively correlated with both the heating time and the atmospheric oxygen concentration. The total amounts of aldehydes were the lowest in the oil heated in an atmosphere with 2% O2, and corresponded to 1/10 of those in the atmosphere with 20% O2. Acrolein was not found in oils heated in the atmosphere with 2% oxygen. These results suggest that frying in atmospheres with low oxygen levels can effectively decrease the generation of volatile aldehydes in the exhaust.
Kinetics of the decomposition of total aliphatic waxes in olive oil during deodorization
Authors: Tubaileh R. M. , Graciani Constante M. M. , Camacho M. Léon , López A. López , Constante E. Graciani
Published: November 2006

Changes in the content of aliphatic waxes during industrial deodorization and/or physical refining of bleached olive oil were studied in an experimental discontinuous pilot plant of 250 kg deodorizer using nitrogen as stripping gas in place of steam. The kinetic constants for the decomposition of waxes during the deodorization process were determined. The reaction orders studied are zero (or can be considered zero) within the working interval. The values of rate constants, activation energy, frequency factor, increment of activation Gibbs free energy, activation enthalpy, and activation entropy are established.
Characterization of sterols in refined borage oil by GC‐MS
Authors: Wretensjö Inger , Karlberg Bo
Published: November 2006

Borage oil sterols were isolated by TLC and characterized using GC and GC‐MS. Several diunsaturated Δ5‐sterols, some of them not previously recorded in vegetable oils, were found. Of these, 24‐methylcholesta‐5,23‐dienol and 24‐ethylcholesta‐5,23‐dienol could be useful markers for borage oil. Two other diunsaturated Δ5‐sterols that are rarely found in vegetable oils, 24‐methylcholesta‐5,24(25)‐dienol and 24‐ethylcholesta‐5,24(25)‐dienol, were identified. The diunsaturated C‐24(28)‐sterol, isofucosterol, was also found, as well as the monounsaturated Δ5‐sterols campesterol and sitosterol. These are normally present in vegetable oils, which makes them unsuitable as markers for borage oil.
Determination of slip melting point in palm oil blends by partial least squares and principal component regression modeling of FTIR spectroscopic data
Authors: Setiowaty G. , Man Y. B. Che
Published: November 2006

The determination of slip melting point (SMP) in refined, bleached, and deodorized palm oil is a common and regular requirement in the manufacture of this oil. An FTIR spectrometer in the mid‐IR wavelength region (4000‐750 cm−1) can provide the basis for a suitable on‐line and off‐line quantitative analytical methodology if used with a suitable calibration model. In this study, by using data from selected regions, the calibration models, including principal component regression and partial least squares regression, have been examined and evaluated for efficacy in determining SMP directly in palm oil blends. Results indicate that orthogonal models using selected wavelength data offer superior predictive performance.
Phosphorus‐to‐phospholipid conversion factors for crude and degummed sunflower oils
Authors: Carelli Amalia A. , Ceci Liliana N. , Crapiste Guillermo H.
Published: November 2006

Phospholipid composition and phosphorus content of several crude and degummed sunflower oils were measured in order to compare theoretical and experimental factors used to convert phosphorus content to phospholipid content. Differences in phospholipid content between sunflower oils obtained by different extraction and degumming methods were also considered. From FA and phospholipid compositions, average theoretical conversion factors of 24.7 and 23.0 were found for crude and degummed sunflower oils, respectively. The experimental conversion factor for degummed oils was in good agreement with the theoretical value. In contrast, fitted experimental factors were significantly lower for crude oils. The differences could be attributed to phosphorus from sources other than phospholipids and to the presence of minor phospholipids not quantified by chromatographic analysis. The relative phospholipid concentrations of oils depended on the method of extraction and the type of degumming. Solvent‐extracted oils had a higher total phospholipid content, being generally more concentrated in PC and PE. The content of nonhydratable phospholipids was relatively low; acid or enzymatic degumming removed 40 to 70% of these phospholipids.
Extraction and analysis of ceramides from internal wool lipids
Authors: Coderch L. , Fonollosa J. , Martí M. , Garde F. , de la Maza A. , Parra J. L.
Published: November 2006

This study sought to obtain internal wool lipid extracts rich in ceramides from different wool types. Extraction methods, i.e., Soxhlet extraction with different organic solvents and supercritical fluid extraction with CO2 using several polarity modifiers such as MeOH or EtOH, were optimized. The internal wool lipid content varied from 0.2 to 1.9% (based on wool weight) with a ceramide content ranging from 15 to 30% (based on extract weight). The Spanish and Russian Merino wool extracts were the richest in ceramide compounds. TLC‐FID was used to quantify the different internal wool lipid extracts. A new experimental protocol that enabled us to identify most of the different ceramide types is presented. These internal wool lipid extracts, especially the ones with a high ceramide content, may be regarded as an alternative source of animal ceramides, which could be of value in the cosmetic and dermopharmaceutical industries.
Hydrogenated vegetable oils as candle wax
Authors: Rezaei Karamatollah , Wang Tong , Johnson Lawrence A.
Published: November 2006

Partially hydrogenated soybean oil, referred to as soywax, is gaining attention as a renewable and biodegradable alternative to paraffin wax for use in candles. However, current soywax candles suffer from several problems, especially poor melting and solidification properties. Fully hydrogenated soybean oil exhibits improved melting properties but owing to its fragile texture, it is not yet acceptable in most candle applications. In the present work, KLXTM (a wax composed of fractionated hydrogenated soy and cottonseed oils) was used as a base material for candles, and the effects of additives such as hydrogenated palm oil (HPO), FFA, and paraffin on the textural and combustion properties were evaluated. Melting and solidification profiles of KLX were better than those of fully hydrogenated soy oil. Adding FFA improved the solidification properties of KLX candles. Adding paraffin improved the compressibility of the wax, while HPO addition decreased hardness and compressibility. Changing the candle diameter and/or wick size along with changing the wax composition resulted in candles with desirable quality attributes.
Stereospecific analysis of TAG from sunflower seed oil
Authors: Boukhchina Sadok , Gresti Joseph , Kallel Habib , Bézard Jean
Published: November 2006

Stereospecific analysis of TAG from a sunflower seed oil of Tunisian origin was performed. The TAG were first fractionated according to chain length and degree of unsaturation by RP‐HPLC. The four major diacid‐ and triacid‐TAG fractions were palmitoyldilinoleoyl‐glycerol, dioleoyllinoleoylglycerol, oleoyldilinoleoylglycerol, and palmitoyloleoyl‐linoleoyl‐glycerol, amounting to 7.2, 16.6, 29.5, and 12 mol%, respectively. The TAG of the four fractions were individually submitted to stereospecific analysis, using a Grignard‐based partial deacylation, separation of sn‐1,2(2,3)‐DAG from sn‐1,3‐DAG by boric acid‐impregnated silica gel TLC plates, conversion of the sn‐1,2(2,3)‐DAG to their 3,5‐dinitrophenylurethane (DNPU) derivatives, fractionation of DNPU derivatives by RP‐HPLC, resolution of the DNPU‐DAG by HPLC on a chiral column, transmethylation of each sn‐DNPU‐DAG fraction, and analysis of the resulting FAME by GC. The data obtained were used to determine the triacyl‐sn‐glycerol composition of the main TAG of the oil. Fifteen triacyl‐sn‐glycerols were identified and quantified, representing, along with the monoacid‐TAG, trilinoleoylglycerol and trioleoylglycerol, more than 90% of the total oil TAG. The two major triacyl‐sn‐glycerols were trilinoleoyl‐glycerol and 1‐linoleoyl‐2‐linoleoyl‐3‐oleoyl‐glycerol (18.6 and 18.5% of the total, respectively). Results clearly identified linoleic acid as the major FA at the sn‐2 position, whereas oleic and palmitic acids were the major FA at the sn‐3 position. The sn‐1 position was occupied to nearly the same extent by linoleic and oleic acids, and to a greater extent by palmitic acid, which was practically absent at the sn‐2 position.
Partial purification ofNigella sativaL. Seed lipase and its application in transesterification reactions
Authors: Tuter Melek , Secundo Francesco , Riva Sergio , Aksoy H. Ayşe , Ustun Guldem
Published: November 2006

Nigella sativaL. seed lipase isolated from defatted seeds was partially purified and used as catalyst in transesterification reactions. Purification of an ammonium sulfate‐precipitated sample (at 35% saturation,Nigella PL) by DEAE ion‐exchange chromatography increased the specific activity from 13.9 to 156.7 U/mg protein.Nigella PLandNigella CPL(the partially purified enzyme sample obtained by DEAE ion‐exchange chromatography) catalyzed the transesterification of vinyl acetate with octanol, with racemic sulcatol (6‐methyl‐5‐hepten‐2‐ol), and with racemictrans‐sobrerol (trans‐p‐menth‐6‐ene‐2,8‐diol) in different organic solvents. Both activity and enantioselectivity of the enzyme samples used for these biotransformations were affected by the nature of the organic solvent.
Phase equilibrium and crystallization behavior of mixed lipid systems
Authors: Liang Baomin , Shi Yuping , Hartel Richard W.
Published: November 2006

As complex lipid systems, the phase and crystallization behavior of mixtures of a high‐melting milk fat fraction with a low‐melting milk fat fraction or canola oil was studied. A turbidity technique was developed to estimate solubility and metastability conditions of these lipid mixtures. Both solubility and metastability of the high‐melting milk fat fraction in liquid lipids increased exponentially with temperature. At a given equilibration temperature, liquid phases and solid fractions with nearly identical melting profiles and TAG compositions were obtained regardless of the original concentration of the lipid mixture. The maximum melting temperature (MMT), as measured by DSC, of the liquid phase increased dramatically in the equilibrium temperature range of 27.5–35.0°C but did not change at temperatures below and above this range (down to 25.0°C and up to 40°C in this study). The content of long‐chain TAG (C46−C52) increased and short‐chain TAG (C36−C40) decreased in the liquid phases as the equilibrium temperature increased. A plot of the TAG group ratio (i.e, long‐short‐chain TAG) vs. equilibrium temperature was generated to illustrate the phase behavior of the complex lipid system and to represent a solubility curve, from which the supersaturation level for crystallization kinetics was determined. Higher supersaturation and lower temperature resulted in higher nucleation and crystallization rates. Compared to the system with a low‐melting milk fat fraction, mixtures of the high‐melting milk fat fraction with canola oil had higher nucleation and crystallization rates due to the lower solubility found for this system.
Ethyl esters from the single‐phase base‐catalyzed ethanolysis of vegetable oils
Authors: Zhou Weiyang , Konar Samir K. , Boocock David G. B.
Published: November 2006

The effects of alcohol/oil molar ratio, base concentration, and temperature on the single‐phase base‐catalyzed ethanolyses of sunflower and canola oils were determined. The use of tetrahydrofuran as co‐solvent, as well as higher than usual alcohol/substrate molar ratios, prevented glycerol separation. This allowed each reaction to reach equilibrium rather than just steady‐state conditions. High conversions of oil lowered the concentrations of MG and DG surfactants in the products, and thereby mitigated the formation of emulsions usually associated with ethanolysis reactions. An alcohol/oil molar ratio of 25∶1, together with the necessary amount of cosolvent, gave optimal results. At this molar ratio, despite equilibrium being achieved, ethanolysis, unlike methanolysis, did not quite produce biodiesel‐standard material, the MG content being approximately 1.5 mass%. For methanolysis and 1‐butanolysis, the corresponding values were 0.6 and 2.0 mass%, respectively. The use of 1.4 mass% KOH (equivalent to 1.0 mass% NaOH) led to ethanolysis equilibrium within 6–7 min at 23°C rather than 15 min when only 1.0 mass% was used. At 60°C, equilibrium was reached within only 2 min. Soybean and canola oils behaved the same.
Oil production from catfish viscera
Authors: Sathivel Subramaniam , Prinyawiwatkul Witoon , King Joan M. , Grimm Casey C. , Lloyd Steven
Published: November 2006

Oil was extracted from catfish viscera and purified (degummed, neutralized, bleached, and deodorized). The yield of catfish oil after purification was 65.7%. The major yield loss took place during the degumming process. The FA found in crude catfish visceral oil were 14∶0, 16∶0, 16∶1, 18∶0, 18∶1, 18∶2, 18∶3, 20∶0, 20∶1, 20∶2, 20∶3, 20∶4, and 22∶6, the predominant FA being 18∶1, 16∶0, 18∶2, and 18∶0. The total unsaturated FA in the purified catfish oil amounted to 67.7%. The combined n−3 FA content of the purified catfish oil was 4.6 mg/g of oil. The purified catfish oil contained 1.21 mg/g DHA. FFA, water activity, and some mineral contents decreased during purification. Bleaching removed pigments, thus resulting in oil with greater lightness and less yellowness.
Cyclic FA monomers in high‐oleic acid sunflower oil and extra virgin olive oil used in repeated frying of fresh potatoes
Authors: Romero A. , Cuesta C. , Sánchez‐Muniz F. J.
Published: November 2006

The measurement of FA profile, polar material, oligomers, oxidized triacylglycerols (OTG), total polyphenols, and cyclic FA monomers (CFAM) was used to evaluate the alteration of a high‐oleic sunflower oil (HOSO) and an extra virgin olive oil (EVOO) used in 75 domestic fryings of fresh potatoes with frequent replenishment (FR) of unused oil. CFAM were absent in the unused EVOO but appeared in small amounts in the unused HOSO. Although polar material, oligomers, OTG, and CTAM contents increased and linoleic acid and polyphenols content decreased in both oils during repeated frying, the changes produced should be considered small and related to the use of very stable oils and FR. Throughout the 75 fryings, the total CFAM concentration was higher in HOSO than in EVOO. OTG increased more quickly in EVOO, whereas oligomers increased more quickly in HOSO. Polar material and oligomer content appear significantly correlated (r=0.9678 and r=0.9739, respectively; for both, P<0.001) with the CFAM content. A 25% polar material and 12% oligomer content would correspond to about 1 mg·kg−1 oil of CFAM. Data suggest that both oils, particularly EVOO, perform very well in frying, with a low production of oligomers, polar materials, and CFAM.
Genetic diversity for lipid content and fatty acid profile in rice bran
Authors: Goffman Fernando D. , Pinson Shannon , Bergman Christine
Published: November 2006

Rice (Oryza sativa L.) bran contains valuable nutritional constituents, which include lipids with health benefits. A germplasm collection consisting of 204 genetically diverse rice accessions was grown under field conditions and evaluated for total oil content and fatty acid (FA) composition. Genotype effects were highly statistically significant for lipid content and FA profile (P<0.001). Environment (year) significantly affected oil content (P<0.05), as well as stearic, oleic, linoleic, and linolenic acids (all with P<0.01 or lower), but not palmitic acid. The oil content in rice bran varied relatively strongly, ranging from 17.3 to 27.4% (w/w). The major FA in bran oil were palmitic, oleic, and linoleic acids, which were in the ranges of 13.9–22.1, 35.9–49.2, and 27.3–41.0%, respectively. The ratio of saturated to unsaturated FA (S/U ratio) was highly related to the palmitic acid content (r2=0.97). Japonica lines were characterized by a low palmitic acid content and S/U ratio, whereas Indica lines showed a high palmitic acid content and a high S/U ratio. The variation found suggests it is possible to select for both oil content and FA profile in rice bran.
Contribution of FA profile obtained by high‐resolution GC/chemometric techniques to the authenticity of green and roasted coffee varieties
Authors: Rui Alves M. , Casal S. , Oliveira M. B. P. P. , Ferreira M. A.
Published: November 2006

Twenty‐four coffee samples of different botanical and geographical origins were analyzed for their FA composition, including trans isomers. The analysis used high‐resolution GC/FID/CP Sil 88 capillary column to separate FAME obtained by esterification with BF3/methanol. The purpose of this work was to verify whether this parameter could be applied in the discrimination of arabica and robusta coffees, either in green or in roasted stage. Statistical approaches were applied to check the efficiecies of some univariate and multivariate procedures, and the results permitted the conclusion that the FA profile can be used as a coffee variety marker and may inform on the historical background, mainly in terms of heat‐processing conditions.
Enzymatic kinetic resolution of secondary alcohols by esterification with FA under vacuum
Authors: Irimescu Roxana , Saito Takao , Kato Katsuya
Published: November 2006

Kinetic resolution of some chiral secondary alcohols [2‐octanol, 1‐phenylethanol, and 1‐(2‐naphthyl)ethanol] with high enantioselectivity (E>300) was achieved by direct esterification with FFA catalyzed by immobilized Candida antarctica B lipase. The reaction equilibrium was shifted toward the synthetic side by the removal of the water formed under vacuum. Esterification of rac‐2‐octanol at an alcohol/FFA molar ratio of 2∶1 was used as a model reaction. The chain length of FFA and their structure influenced the reaction rate but did not have a measureable effect on E. The best acyl donor was decanoic acid: >47% conversion at 4 h with virtually perfect E. Temperature did not affect E in the range studied (15–45°C), but temperatures at the higher end afforded improved reaction rates. The reaction rates and E were compared for three different acyl donors. The initial reaction rate increased in the following order: ethyl laurate < lauric acid < vinyl acetate. E was high (E>300) for all acyl donors. Racemic 1‐phenylethanol and 1‐(2‐naphthyl)ethanol were also resolved by direct esterification with decanoic acid in short times (3 and 4 h, respectively) with E>300 and excellent conversions. Preparative‐scale kinetic resolution of 2‐octanol was also performed.
The influence of antioxidants on the oxidation stability of biodiesel
Authors: Mittelbach Martin , Schober Sigurd
Published: November 2006

Oxidation stability of bodiesel is an important issue because FA derivatives are more sensitive to oxidative degradation than mineral fuel. Therefore, in the most recent European Specifications for biodiesel, a minimum value of 6 h for the induction period at 110°C, measured with a Rancimat instrument, is specified. To guarantee this value at the filling station, the use of additional antioxidants will be necessary. In this paper we show the influence of different synthetic and natural antioxidants on the oxidation stability, using the specified test method. Biodiesel produced from rapeseed oil, sunflower oil, used frying oil, and beef tallow, both undistilled and distilled, was investigated. The four synthetic antioxidants pyrogallol (PY), propylgallate (PG), TBHQ, and BHA produced the greatest enhancement of the induction period. These four compounds and the widely used BHT were selected for further studies at concentrations from 100 to 1000 mg/kg. The induction periods of methyl esters from rapeseed, oil, used frying oil, and tallow could be improved significantly with PY, PG, and TBHQ, whereas BHT was not very effective. A good correlation was found between the improvement of the oxidation stability and the FA composition.
Lipase‐catalyzed interesterification reaction between menhaden oil and the ethyl ester of CLA: Uniresponse kinetics
Authors: Torres Carlos F. , Lin Betty , Lessard Louis P. , Hill Charles G.
Published: November 2006

The kinetics of the interesterification reaction between menhaden oil and the ethyl ester of CLA (CLAEE) in the presence of an immobilized lipase from Rhizomucor miehei was investigated. A 23 factorial design with a central point was used to define the experimental region. The factors considered were the molar ratio of reactants, the enzyme loading, and the temperature. Optimal results were obtained when the reaction was carried out at 55°C with an enzyme loading of 0.65 g per 12 g mixture and a mole ratio of CLAEE to menhaden oil equal to 0.13. A uniresponse kinetic model of the Michaelis‐Menten type was developed to characterize the rate of consumption of CLAEE and the rate of release of FA ethyl esters from menhaden oil. The best fit of the data with a uniresponse model was obtained using a form based on reversible reactions and inhibition by the ethyl esters of the FA residues released by the reaction.
Chemical and sensory properties of gas‐purged, minimum‐refined, extruded‐expelled soybean oil
Authors: Wang Xi , Wang Tong , Johnson Lawrence A.
Published: November 2006

Developing low‐cost oil refining methods is critical to business that use low‐cost extrusion‐expelling (E‐E) to crush soybeans so they can capture the full value‐added potential by marketing finished oils. Normal commodity (CO) and high‐oleic (HO) E‐E soybean oils were minimum‐refined, gas‐purged, and evaluated in frying applications. Degummed commodity oil (DCO) and minimum‐refined (degummed and deacidified by Magnesol® adsorption) CO and HO oils were gas‐purged with N2 for 1 h at 150°C. For DCO, gas purging did not affect PV, oxidative stability index (OSI), FFA, color, and total tocopherol content, but p‐anisidine value (AV) increased. For CO, the minimum‐refined, gas‐purged oil did not differ from degummed, gas‐purged oil in terms of p‐AV, OSI, tocopherol content, and color. PV and FFA were lower in minimum‐refined, gas‐purged oil. Minimum‐refined, gas‐purged HO had much higher OSI, tocopherol, and FFA levels than did minimum‐refined, gas‐purged CO. The oils were used to fry bread cubes at 185°C. Fried bread cubes were stored under various conditions and evaluated for flavor attributes. These oils were different in toasty/nutty, beany/grassy, and oxidized flavors, as well as overall flavor intensity and desirability. Minimum‐refined, gas‐purged oils produced fried bread cubes having initial flavor profiles similar to those fried in commercial oil; however, when fresh oils were used they were less stable to oxidation. Longer heating times of the minimum‐refined, gas‐purged oils produced bread cubes with better oxidative stabilities than those produced with commercial oil.
Ozonation of sunflower oil: Spectroscopic monitoring of the degree of unsaturation
Authors: Soriano Nestor U. , Migo Veronica P. , Matsumura Masatoshi
Published: November 2006

Consumption of ozone by unsaturated FA moieties of sunflower oil (SFO) was monitored by 1H NMR and FTIR spectroscopy. Degradation of linoleate was found to be 1.5 and 1.8 times higher than oleate when SFO was ozonized in the absence and presence of water, respectively. Products of ozonation in both cases include aldehydes and ozonides with 1,2,4‐trioxolane ring. Hydroxyl‐containing compounds, which could be carboxylic acids and/or hydroperoxides, were also detected in samples ozonized in the presence of water. The extent of ozonation had very little effect on the aldehyde/ozonide ratio obtained from NMR spectra, especially in the ozonation of neast SFO. The aldehyde/ozonide ratios obtained regardless of the extent of ozonation were 10.5:89.5 and 46.6:53.4 for SFO ozonized in the absence and presence of water, respectively.
Preparation of long‐chain β‐enaminones and β‐diketones from long‐chain 3,5‐disubstituted isoxazole compounds
Authors: Kenar James A.
Published: November 2006

A series of long‐chain compounds containing the β‐enaminone functionality were prepared in yields ranging from 71 to 88% from their corresponding long‐chain 3,5‐disubstituted isoxazole precursors utilizing a Raney nickel‐catalyzed reductive ring‐opening procedure. These newly prepared multifunctional compounds were subsequently hydrolyzed under mild acidic conditions (pH 4–5) to give their corresponding long‐chain β‐diketones in yields ranging from 79 to 98%. Both the β‐enaminone and β‐diketone functionalized compounds were characterized by NMR, IR spectroscopy, GC‐MS, and m.p. The mass spectra for these two classes of compounds, derived by utilizing electron impact ionization, gave distinctive McLafferty rearrangement fragmentation ions that clearly established the newly introduced functionality to reside at the C‐2 and C‐4 positions of the lipid’s alkyl chain. 1H NMR spectra of the pure β‐diketone compounds were complex owing to the keto enol tautomerism displayed by the β‐diketone moiety. In solution the β‐diketone compounds were shown to exist mainly in the enolic tautomeric form. Long‐chain β‐diketone compounds are known to be relatively common constituents of some plant waxes, and the overall procedure starting from soybean methyl esters provides a complementary approach to prepare these types of compounds.
Determination of nonvolatile components in polar fractions of rice bran oils
Authors: Abidi S. L. , Rennick K. A.
Published: November 2006

High‐oryzanol rice brain oil (HORBO), rice bran oil (RBO), and partially hydrogenated soybean oil (PHSBO) were used to prepare french fries. Polar fractions of the three oils were analyzed for nonvolatile components by high‐performance size‐exclusion chromatography (HPSEC) with ELSD. In all frying experiments, both HORBO and RBO yielded predominantly dimeric and monomeric materials. The concentrations of polymeric species in HORBO and RBO were greater than in PHSBO. The major degradation products from HORBO, RBO, and PHSBO were dimers (8.93 mg/100 mg oil), monomers (10.5 mg/100 mg oil), and DG (22.4 mg/100 mg oil), respectively. Thermal degradation via hydrolysis was much greater in PHSBO than in HORBO or RBO. Distribution data indicated that the extent of polymer formation from frying was in the order RBO>HORBO >PHSBO, consistent with the degree of lipid unsaturation and the oryzanol content in these oils. HPSEC‐ELSD results from the two RBO showed that the amounts of various polymeric species, including trimers and higher polymers, were lower in HORBO than in RBO. The percentage of polar materials and the percentage of polymerized TG, which were used as indicators of oil quality and stability, decreased with increasing tocopherol and oryzanol contents in the order PHSBO>HORBO>RBO.
Immobilization of Candida rugosa lipase by sol‐gel entrapment and its application in the hydrolysis of soybean oil
Authors: Noureddini H. , Gao X. , Joshi S.
Published: November 2006

Immobilization of lipase AY from Candida rugosa by entrapment within a chemically inert hydrophobic sol‐gel support was studied. The gel‐entrapped lipase was prepared by polycondensation of hydrolyzed tetramethoxysilane and isobutyltrimethoxysilane. Certain modifications were incorporated into the conventional immobilization procedure, including the use of glucose as additive and the application of vacuum during the drying and aging stages. The activity and thermostability of immobilized enzyme were subsequently determined in hydrolyzing soybean oil. Hydrolysis results showed more than 95 mol% of the theoretical yield for the formation of FF after 1 h of reaction at 40°C. The level of FFA was 3.3 times greater than that seen when an immobilized enzyme was prepared by the conventional sol‐gel process. The immobilized enzyme retained most of its hydrolytic activity compared to the free enzyme and kept more than 95% activity after 120 h of incubation at 40°C, whereas the free enzyme lost 67% of its activity after 24 h of incubation and almost all of its activity after 96 h of incubation at 40°C. The immobilized enzyme also proved to be very stable, as it retained more than 90% of the initial activity after 16 one‐hour reactions. Surface characterization studies suggested that the enzyme‐containing sol‐gel particles have amorphous morphology and are void of micro/meso pores.
Bioconversion of n−3 and n−6 PUFA by Clavibacter sp. ALA2
Authors: Hosokawa Masashi , Hou Ching T. , Weisleder Dave
Published: November 2006

Clavibacter sp. ALA2 oxidized n−3 and n−6 PUFA into a variety of oxylipins. Structures of products converted from EPA and DHA were determined as 15,18‐dihydroxy‐14,17‐epoxy‐5(Z),8(Z),11(Z)‐eicosatrienoic acid and 17,20‐dihydroxy‐16,19‐epoxy‐4(Z),7(Z),10(Z),13(Z)‐docosatetraenoic acid by GC‐MS and NMR analyses. In contrast, γ‐linolenic acid and arachidonic acid were converted to diepoxy bicyclic FA, tetrahydrofuranyl monohydroxy FA, and trihydroxy FA. Thus, the structures of bioconversion products were different between n−3 and n−6 PUFA. Furthermore, strain ALA2 placed hydroxy groups and cyclic structures at the same position from the ω‐terminal despite the number of carbons in the chain and the double bonds in the PUFA.
Oleic acid content in ground corn by NIR spectroscopy with an indirect calibration method
Authors: Wright Steve , Hagen Lisa
Published: November 2006

Developing corn hybrids with improved FA profiles is important in providing products with enhanced nutritional characteristics. To support this effort, rapid screening methods are needed to track the various traits of interest. In using NIR methods, calibrations are based on an assumed linear relationship between the concentration of the analyte of interest and the absorbance of the sample. Although this point seems obvious, this linear relationship does not exist when using GC analysis as a reference method for oleic acid content in ground corn kernels. In this case, the GC data provide a relative oleic acid content of the oil and not of the grain from which the NIR spectrum is measured. A method of removing this nonlinearity by modeling the absolute oleic acid content in the grain has been developed. The relative oleic acid content of the oil is then calculated from this predicted absolute oleic acid value, and the total oil content of the grain is predicted from another calibration model. Significant improvement in the model's predictive ability is demonstrated using this two‐calibration model.
Comparison of kjeldahl and dumas methods for determining protein contents of soybean products
Authors: Jung S. , Rickert D. A. , Deak N. A. , Aldin E. D. , Recknor J. , Johnson L. A. , Murphy P. A.
Published: November 2006

The Kjeldahl and Dumas methods for quantifying nitrogen content were compared using nine soybean products having protein contents ranging from 0.5 to 90%. In addition to comparing day‐to‐day variability of the Dumas method, differences between and variabilities of two Kjeldahl systems and Kjeldahl operators were also evaluated. The Kjeldahl method gave slightly, but significantly, lower values than did the Dumas method. Both the Kjeldahl and Dumas methods had equivalent variabilities (same SD about the means). The ratios between the means for the Kjeldahl and Dumas (K/D) protein values ranged from 0.66 to 1.03. The conversion equation y=−0.00536+0.97188x (R2=0.9997) was developed and validated to convert from Dumas to kjeldahl protein concentrations.
Relative FFA formation and lipid oxidation of commercially milled unseparated, head, and broken rice
Authors: Monsoor Mamun A. , Proctor Andrew
Published: November 2006

This study was conducted to determine the relative rate of FFA formation and lipid oxidation of unseparated (head and broken), head, and broken rice and the effect of water washing on the lipid quality of broken rice. A regression model was developed with surface FFA or conjugated diene (CD) content vs. incubation time to determine the rates of FFA formation and lipid oxidation. The surface lipid contents of unseparated, head, and broken rice were 0.40, 0.38, and 0.50% of rice, respectively. FFA formation during storage showed three phases: an initial rapid formation, followed by a period of very little or no formation, and finally a phase of gradual formation. In contrast, CD formation initially showed a slow increase but later increased gradually with storage time. The relative rates of FFA and CD formation of unseparated, head, and broken rice were 0.0028, 0.0027, and 0.0036 and 0.192, 0.188, and 0.377, respectively. Water washing reduced the rates of FFA formation and lipid oxidation of broken rice to 0.0015 and 0.2192 from initial values of 0.0031 and 0.369, respectively. Water washing appears to be a simple and practical means of lowering the rates of FFA formation and lipid oxidation in broken rice.
Pigment parameters determining spanish virgin olive oil authenticity: Stability during storage
Authors: Roca María , Gandul‐Rojas Beatriz , Gallardo‐Guerrero Lourdes , Mínguez‐Mosquera M. Isabel
Published: November 2006

The chlorophyll and carotenoid pigment composition in 12 mono‐variety virgin olive oils was examined every 30 d during 1 yr of storage at 15°C in darkness. The oil authenticity parameters, as defined by the ratio of chlorophylls/carotenoids and the ratio of minor carotenoids/lutein, remained stable throughout storage, irrespective of the variety and degree of ripeness of the source fruit. The percent of violaxanthin, percent of lutein, and total pigment content, the classifying variables chosen as the best possible discriminators among olive varieties, also remained stable during storage. The prediction model for olive variety, which was based on a discriminant multivariate analysis of the observed values of these variables, gave a correct classification in 99.6% of the oils analyzed. The discriminant criterion established remained valid after 1 yr of oil storage. The detection of chlorophyll derivatives other than those associated with the physical extraction process was seen as a quality index, as small, analytically detectable transformations in the structure of pigments were indicative of oil storage.
A rigorous kinetic model for β‐carotene oxidation in the presence of an antioxidant, α‐tocopherol
Authors: Takahashi Atsushi , Shibasaki‐Kitakawa Naomi , Yonemoto Toshikuni
Published: November 2006

Oxidation of β‐carotene in an inert solvent, n‐decane, in the presence of various concentrations of the antioxidant α‐tocopherol was studied. The progress of carotene oxidation was suppressed as long as the tocopherol remained in the system. A rigorous kinetic model for carotene oxidation in the presence of an antioxidant was proposed based on a reaction mechanism in which not only the antioxidation but also the co‐oxidation and radical‐exchange reaction of tocopherol with carotene were incorporated. The model quantitatively described the oxidation behavior of carotene over a wide range of temperatures, oxygen compositions, and initial antioxidant concentrations.
Speed of sound and isentropic bulk modulus of alkyl monoesters at elevated temperatures and pressures
Authors: Tat Mustafa Ertunc , Van Gerpen Jon H.
Published: November 2006

Biodiesel is a biodegradable, sulfur‐free, oxygenated, and renewable alternative diesel fuel consisting of the alkyl monoesters of FA from vegetable oils and animal fats. Biodiesel can be used in existing diesel engines without significant modifications. However, differences in physical properties between biodiesel and petroleum‐based diesel fuel may change the engine's fuel injection timing and combustion characteristics. These altered physical and chemical properties also may cause the exhaust emissions and performance to differ from the optimized settings chosen by the engine manufacturer. In particular, the density, speed of sound, and isentropic bulk modulus have a significant effect on the fuel injection system and combustion. The objective of this study was to measure these three properties for biodiesel (and the pure esters that are the constituents of biodiesel) at temperatures from 20 to 100°C and at pressures from atmospheric to 32.5 MPa. Ten different biodiesel fuels, 16 different pure FA esters, three hydrocarbons, and one diesel fuel were tested. The measured values of density, speed of sound, and isentropic bulk modulus are presented. Correlations between pressure and temperature are demonstrated. Speed of sound and isentropic bulk modulus tend to increase as the degree of unsaturation increases and as the chain length increases. However, density increased with shorter chain length and decreased with saturation.
Structuring of edible oils by long‐chain FA, fatty alcohols, and their mixtures
Authors: Gandolfo François G. , Bot Arjen , Flöter Eckhard
Published: November 2006

Homologous series of fatty alcohols and FA with chain lengths ranging from 16 to 22 carbons were evaluated for their oil‐structuring potential by texture profile analysis (TPA). FA, fatty alcohols, and their mixtures were found to structure sunflower oil and several vegetable oils at levels as low as 2% (w/w) for the pure ingredients. Mixtures of fatty alcohols and FA with the same chain lengths, at 5% (w/w) in sunflower oil, showed a synergistic effect below 20°C at the composition ratios of 7∶3 and 3∶7 (w/w). This synergistic effect in the 7∶3 stearyl alcohol/stearic acid mixture was due to effects on the microstructure of the composite material. The larger number of small crystals observed in the mixture was attributed to effects on the crystallization kinetics as a result of minimal interfacial tension at the specific 1∶3 and 3∶1 molecular ratios.
Rapid determination of oxidative stability of edible oils by FTIR spectroscopy using disposable IR cards
Authors: Russin Ted A. , van de Voort Frederick R. , Sedman Jacqueline
Published: November 2006

Disposable polytetrafluoroethylene (PTFE) polymer IR (PIR) cards were used as substrates to rapidly oxidize edible oils and simultaneously monitor the extent of oxidation by FTIR spectroscopy. Four edible oils were oxidized on PIR cards and in bulk at moderate temperature (58°C), and real‐time oxidation plots were obtained by measuring changes in the IR hydroperoxide (ROOH) absorbance as a function of time. The relationship between the ROOH absorbance and PV was developed using a reference method to define absorbances corresponding to PV end points of 100 and 200 meq ROOH/kg for the oils oxidized in bulk and on cards, respectively. The real‐time oxidation plots obtained for the oils oxidized in bulk and on cards were similar in appearance, but the oils on the cards reached the PV end point 20 times faster than the oils oxidized in bulk. The results indicate that the use of disposable PIR cards coupled with moderate heating and aeration provides a simple, practical, and rapid means for monitoring oxidation and determining the oxidative stability of edible oils at a normal storage temperature.