bluuebunny/crossref_metadata_2025 huggingface dataset:
Heated fat, vitamin E and vascular eicosanoids
Authors: Giani E. , Masi I. , Galli C.
Published: November 2006

A semisynthetic diet containing adequate amounts of vitamin E and 10% (w/w) of a mixture of polyunsaturated oils subjected to heating and characterized by elevated indexes of thermal alteration (polar component, dimer triglyceride, altered triglyceride contents and reduced α‐tocopherol levels) was fed to growing male rats for a period of eight weeks. It resulted in a selective alteration of the production of vascular eicosanoids (elevation of platelet thromboxane formation and decrease of vascular prostacyclin release) compared to the values found in rats fed a diet containing a fresh mixture of polyunsaturated oils. Major nutritional parameters, plasma lipids and the fatty acid profiles of plasma, liver and heart lipids were not different in the two groups of animals. Supplementation of an excess vitamin E (300 mg/kg) to the diet containing heated fat neutralized the adverse effects of heated fat on vascular eicosanoid production.
Metabolism of lysophosphatidylcholine by swine platelets
Authors: Chen Dian‐er , White Arnold A. , Tumbleson M. E. , Sun Grace Y.
Published: November 2006

Incubation of intact platelets from Sinclair(S‐1) miniature swine with32P‐labeled lysophosphatidylcholine (lyso PC) indicated the presence of an active lysophospholipase with a pH optimum of 8.0 for hydrolysis of the substrate. However, lyso PC was incorporated into the membrane phosphatidylcholines by the acyltransferase pathway upon addition of ATP, Mg++ and CoA to the platelet suspension. These results suggest that intact platelets are able to resist the cytotoxic effects of lyso PC in plasma, and the phospholipids in platelet membranes are not readily affected by the lipid environment of the plasma. The acyltransfer reaction apparently is saturated with endogenous free fatty acids since arachidonic acid added exogenously did not further enhance the incorporation activity. Neither the acyltransferase nor the lysophospholipase activity was affected by Ca++, but divalent metal ions such as Zn++ inhibited the lysophospholipase activity. Cholesterol but not cholesteryl esters elicited a biphasic effect on both enzymes, stimulating at low concentration but inhibiting at a cholesterol to lyso PC ratio greater than 1. Serum albumin inhibited the lysophospholipase but gave a small biphasic effect to the acyltransferase.
Temperature‐induced phase change in a fat. A study by electron spin resonance
Authors: Le Meste Martine , Cornily Gérard , Simatos Denise
Published: November 2006

Electron Spin Resonance, Differential Scanning Calorimetry and rheological techniques have been used to study the physical changes induced by temperature in lard and in the solid and liquid fractions obtained by fractionation of lard at 15 C. The mobilization process of a C18 fatty acid nitroxide derivative dispersed in the molten fat has been observed in the temperature range −50 to +70 C.

The mobilization of the probe seemed to be concomitant with the melting of the low melting point glycerides. Above this temperature, all the probes were in the liquid phase and their mobility reflected the viscosity of their liquid environment, or the viscosity of the bulk fat when crystal was no longer present.

Probe mobility was temperature dependent, and it was identical for the three fats at the same temperature, despite their different triglyceride compositions.
Analysis of deuterium labeled blood lipids by chemical ionization mass spectrometry
Authors: Rohwedder William K. , Emken Edward A. , Wolf Darhal J.
Published: November 2006

A quantitative analytical method has been developed to analyze methyl esters of blood fatty acids derived from human subjects fed deuterium‐labeled fats. The GCMS computer method provides for the analysis of the fed deuterium‐labeled fatty acids, the naturally occurring blood fatty acids and new fatty acids formed by chain elongation or shortening of the fed labeled fats. Approximately 20 fatty acids including 16, 17, 18 and 20 carbon chain acids were analyzed with a relative standard deviation of 0.02 at the microgram level and a sensitivity of less than one nanogram. The method uses capillary GC to separate the fatty acid esters and isobutane chemical ionization mass spectrometry with multiple ion detection to determine the isotopic constituents of the GC peaks. The technique provides for the determination of overlapping GC peaks labeled with 2, 4 and 6 deuterium atoms and makes extensive use of computers both for data acquisition and processing.
Appropriate discounting leads to forward‐looking ecosystem management
Authors: Carpenter Stephen R. , Brock William A. , Ludwig Donald
Published: November 2006

Ecology and economics share many intellectual challenges, such as uncertainty about future system dynamics. An appropriate consideration of our uncertainty about our economic future leads to discounting of benefits of ecosystem services at the lowest possible rate over long time horizons. This more realistic discounting supports much more conservative and sustainable decisions than conventional discounting.
A kinetic model for co‐oxidation of β‐carotene with oleic acid
Authors: Takahashi Atsushi , Suzuki Jun‐ichi , Shibasaki‐Kitakawa Naomi , Yonemoto Toshikuni
Published: November 2006

Oxidation experiments with β‐carotene in a lipid solution were conducted under various conditions of temperature, oxygen composition, and lipid content. The experimental results were compared with those using n‐decane reported previously. Under all conditions, the oxidation rate in oleic acid was faster than that in n‐decane. A novel kinetic model for the co‐oxidation of carotene with a lipid was proposed based on the reaction mechanism, which consisted of the oxidation of carotene, the oxidation of oleic acid, and the cross‐reaction of carotene with oleic acid. The model quantitatively described the oxidation behavior of carotene over a wide range of temperatures, oxygen compositions, and lipid contents.
A second‐order model for catalytic‐transfer hydrogenation of edible oils
Authors: Mondal Kanchan , Lalvani Shashi B.
Published: November 2006

A second‐order kinetic model for hydrogenation of fatty acids in series has been developed and analyzed. The model is applied to the data obtained for sodium formatecatalyzed hydrogenation of soybean, peanut, corn, and olive oils. There is good agreement between the experimental data and predicted values obtained from the model as evidenced by the analysis of r2 and F‐test values. The effect of individual fatty acid composition of various edible oils on the rate of hydrogenation has been explained in view of the mathematical model developed. The individual rate constants seem to obey the Arrhenius rate law. The second‐order kinetic analysis discussed is found to be suitable for mathematically describing hydrogenation of vegetable oils by hydrogen donors as compared to the traditional first‐order kinetic analysis
Nuclear magnetic resonance characterization of reaction products of interesterification of peracetylated α‐d‐glucopyranose and fatty acid methyl esters
Authors: Kuang Dzulkefly , Obaje Olobo J. , Kassim Anuar , Ee Gwendoline C. L. , Suhaimi Hamdan
Published: November 2006

Mono‐ and diesters of fatty acids of peracetylated α‐d‐glucopyranose were prepared by chemical interesterification. Substituent‐induced chemical shift effects on the carbonyl carbons rather than the ring carbons and proton atoms unambiguosly show the fatty acyl substituents to be at C1 in the monosubstituted, and at C1 and C6 in the disubstituted products. 1H nuclear magnetic resonance (NMR) integration data before and after interesterification complemented 13C chemical shift data in verifying the molecular structures. Empirical data from classical 1H and 13C NMR experiments thus provide a simple self‐contained method for determining the number and position of fatty acyl substituents, and the anomeric compositions of peracetylated glucose fatty esters.
Modification of menhaden oil by enzymatic acidolysis to produce structured lipids: Optimization by response surface design in a packed bed reactor
Authors: Xu Xuebing , Fomuso Lydia B. , Akoh Casimir C.
Published: November 2006

Structured lipids from menhaden oil were produced by enzymatic acidolysis in a packed bed reactor. Response surface methodology was applied to optimize the reaction. Lipozyme IM from Rhizomucor miehei lipase was the biocatalyst, and caprylic acid was the acyl donor. Parameters such as residence time, substrate molar ratio, and reaction temperature were included for the optimization. High incorporation of acyl donor and retention of high levels of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in the original menhaden oil were obtained. Good quadratic models were obtained for the incorporation of caprylic acid and for the content of EPA plus DHA retained, by multiple regression with backward elimination. The coefficients of determination (R2) for the two models were 0.91 and 0.87, respectively. The regression probabilities (P) were below 0.003 for both models. Also, the predicted values from the two models had linear relationships with the observed responses. All parameters studied had positive effects on the incorporation of caprylic acid, but only residence time and substrate molar ratio had negative effects on the content of EPA plus DHA retained. The optimal conditions generated from models were temperature =65°C, substrate molar ratio=4–5, and residence time=180–220 min. Incorporated caprylic acid did not replace DHA, but the content of EPA decreased somewhat with an increase in caprylic acid incorporation.
The effect of oxygen concentration on oxidative deterioration in heated high‐oleic safflower oil
Authors: Fujisaki Mariko , Mohri Satoshi , Endo Yasushi , Fujimoto Kenshiro
Published: November 2006

High‐oleic safflower oil was heated at 180°C in atmospheres with four levels of oxygen concentration (2, 4, 10, and 20%) modified with nitrogen gas, to assess the effects of atmospheric oxygen concentration on the oxidative deterioration of deep‐frying oils. Acid value, carbonyl value, polar materials, linoleic acid, tocopherol contents, and oxidative stability were measured to evaluate the quality of heated oils. These values were found to be correlated with both heating time and oxygen concentration. Acid and carbonyl values and polar material content of oils heated at oxygen concentrations of 2 and 4% were lower than those at 10 or 20%. On the other hand, linoleic acid and tocopherols were hardly reduced in oils after heating for 30 h at 2% O2, whereas they were decomposed according to the oxygen concentration and heating time. Oxidative stability was well maintained in oils heated at 2 and 4% O2. These results suggest that the oxidative deterioration of heated higholeic safflower oil depends on oxygen concentration.
Membrane processing of used frying oils
Authors: Subramanian R. , Nandini K. E. , Sheila P. M. , Gopalakrishna A. G. , Raghavarao K. S. M. S. , Nakajima M. , Kimura T. , Maekawa T.
Published: November 2006

Studies were conducted with used frying oils in a flat membrane batch cell using five different types of polymeric membranes to decrease the soluble degradation products. During membrane processing, triglycerides permeated preferentially compared to the majority of the polar compounds including oxidation products, polymers, and color compounds. Two of the composite membranes, NTGS‐AX and NTGS‐2200, selectively rejected polar compounds and oxidation products to the extent of 25–48% and 24–44% respectively. The reduction in Lovibond color values (5R+Y) was in the range of 83–93%. The viscosity of the used frying oil was reduced to the extent of 22%. The composite membranes were effective in reducing the soluble impurities, as well as insoluble particulates, without causing any undesirable changes to the oil. The membrane process appears to improve the life of used frying oils and does not have the disadvantages associated with the active filtration systems, however, for commercial application the permeate flux needs to be improved considerably.
Enrichment of polyunsaturated fatty acids from sardine cannery effluents by enzymatic selective esterification
Authors: Schmitt‐Rozieres Murielle , Deyris Valérie , Comeau Louis‐Claude
Published: November 2006

The sardine canning industry produces vast quantities of effluents that need expensive reprocessing. Their oily component contains valuable n−3 polyunsaturated fatty acids, namely EPA (5,8,11,14,17‐eicosapentaenoic acid) and DHA (7,10,13, 16,19‐docosahexaenoic acid), up to 10% each. Our aim was to develop a process allowing the recovery of these fatty acids. After removing solid particles, proteins, and peptides from the crude effluent, the obtained oil was hydrolyzed. EPA and DHA were enriched from the recovered free fatty acid fraction by selective enzymatic esterification. Lipases were used as biocatalysts: LipozymeTM allowed up to 80% DHA enrichment but gave no EPA enrichment. By immobilizing Candida rugosa lipase on Amberlite IRC50 cation‐exchange resin, a 30% EPA enrichment was obtained.
Lipase activity and fatty acid typoselectivities of plant extracts in hydrolysis and interesterification
Authors: Caro Yanis , Villeneuve Pierre , Pina Michel , Reynes Max , Graille Jean
Published: November 2006

Lipase fatty acid typoselectivities of Euphorbia characias latex and commercially available crude preparation of bromelain were determined in the hydrolysis of homogeneous triacylglycerols (TAG) and natural TAG mixtures. Their activities were compared to a commercially available crude preparation of papain. Under optimal lipolysis conditions at pH 8.0 and 10 min of incubation time, maximal activities were observed at 45, 55, and 50°C, respectively, for E. characias latex, crude bromelain, and crude papain. Commercially available crude preparations of bromelain exhibited very poor hydrolysis activity. Latex from E. characias, which contained 340 mg of dried material per milliliter of fresh latex, exhibited a high lipase activity and a short‐chain fatty acid preference in the hydrolysis of homogeneous TAG. For all substrates, it showed a better activity than crude papain. Lipase fatty acid typoselectivities of crude bromelain and crude papain also were studied in interesterification reactions of tributyrin with a series of homogeneous TAG. Experiments showed that crude bromelain [water activity (Aw)∶ 0.21] had no activity in interesterification. Regarding reactions with crude papain (Aw∶ 0.55), yields of newly formed TAG decreased with increasing chain length of TAG, except for the reaction with trimargarin. For interesterification of tributyrin with unsaturated TAG, triolein reacted faster than polyunsaturated TAG. During these interesterification reactions, the proportion of new TAG with two butyroyl residues was higher than new TAG with only one butyroyl residue. This phenomenon was more pronounced for reactions with long‐chain TAG.
Epoxidized soybean oil‐based ceramer coatings
Authors: Teng Ganghua , Soucek Mark D.
Published: November 2006

New inorganic/organic hybrid coating containing epoxidized soybean oil were prepared. Three sol‐gel precursors [titanium (IV) i‐propoxide, titanium (IV) di‐i‐propoxide bis‐acetoacetonate, and zirconium n‐propoxide] were utilized as the inorganic phase. Various coating properties, including adhesion, hardness, impact resistance, flexibility and tensile properties, were investigated as a function of sol‐gel precursor type and concentration. All ceramer coatings exhibited excellent flexibility and hardness. Tensile strength and hardness increased with sol‐gel precursor concentration. A slight decrease in adhesion and impact resistance was observed with increasing precursor content.
Crystallization kinetics of fully hydrogenated palm oil in sunflower oil mixtures
Authors: Kloek William , Walstra Pieter , van Vliet Ton
Published: November 2006

The crystallization kinetics of mixtures of fully hydrogenated palm oil (HP) in sunflower oil (SF) was studied. The thermal properties and phase behavior of this model system were characterized by means of differential scanning calorimetry and X‐ray diffraction. From the melting enthalpy and clear point of HP, it was possible to calculate the supersaturation at a given temperature for every composition of the model system. Supersaturation of the model system for the β′ but not for the α polymorph yielded the β′ polymorph, while supersaturation for the α polymorph yielded a mixture of mainly β and some β′ polymorphs. The crystallization kinetics of HP/SF mixtures were determined by pulsed wide‐line proton nuclear magnetic resonance for various initial supersaturations in the β′ polymorph. The determined curves were modeled by a modified classical nucleation model and an empirical crystal growth function, which are both functions of supersaturation. Heterogeneous nucleation rates in the β′ polymorph yielded a surface Gibbs energy for heterogeneous nucleus formation of 3.8 mJ·m−2. About 80% of the triglyceride was assumed to be in a suitable conformation for incorporation in a nucleus. Induction times for isothermal crystallization in the β′ polymorph yielded a surface free energy for heterogeneous nucleus formation of 3.4 to 3.9 mJ·−2.
Synergistic effects of rosemary, sage, and citric acid on fatty acid retention of palm olein during deep‐fat frying
Authors: Jaswir Irwandi , Man Yaakob B. Che , Kitts David D.
Published: November 2006

A study to optimize the use of oleoresin rosemary extract, sage extract, and citric acid in refined, bleached, and deodorized (RBD) palm olein during deep‐fat frying of potato chips was performed using response surface methodology. Results showed that the natural antioxidants used in this study retarded oil deterioration, as evidenced by retention of fatty acid profiles. The linoleic to palmitic (C18∶2/C16∶0) ratio was chosen as the parameter for optimizing the use of natural antioxidants in RBD palm olein during deep‐fat frying. Linoleic (R2=0.946) and palmitic (R2=0.825) acids were found to be the most important dependent variables, giving highest R2 values to various antioxidant treatments after 25 h of frying. All three antioxidants had independent significant (P<0.05) effects on the C18∶2/C16∶0 ratio. In fact, significant effects on the C18∶2/C16∶0 ratio of RBD palm olein were also given by a second‐order form. A combination of 0.076% oleoresin rosemary extract, 0.066% sage extract, and 0.037% citric acid produced the optimal retention of the essential fatty acid C18∶2. In addition, a synergistic effect among these antioxidants on the fatty acid ratio of RBD palm olein was found.
The influence of various emulsifiers on the partitioning and antioxidant activity of hydroxybenzoic acids and their derivatives in oil‐in‐water emulsions
Authors: Stöckmann Heiko , Schwarz Karin , Huynh‐Ba Tuong
Published: November 2006

The partitioning behavior of a series of hydroxybenzoic acids and their derivatives was determined in biphasic water‐oil systems, emulsifier solutions, and oil‐in‐water (O/W) emulsions. The effect of gradually decreasing polarity on partitioning behavior and antioxidant efficiency in O/W emulsions was investigated by using gallic acid and its esters as antioxidants. Sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), polyoxyethylene 20 cetyl ether (Brij 58), and partially hydrolyzed soybean lecithin (PHLC, Emultop®) were used to investigate the influence of different classes of emulsifiers on the partitioning behavior. The antioxidant activity of gallic acid and its methyl, ethyl, propyl, butyl, and octyl esters showed markedly different trends in O/W emulsions depending on the emulsifier used. The results are discussed with respect to the properties of the emulsifiers, such as hydrogen bond basicity, hydrophobic interactions, and structural properties.
Effects of microwave and conventional baking on the oxidative stability and fatty acid composition of puff pastry
Authors: Daglioglu Orhan , Tasan Murat , Tuncel Baris
Published: November 2006

The effects of microwave and conventional baking on the fatty acid and trans fatty acid compositions of puff pastries, which contain high amounts of hydrogenated fat, were investigated. In addition, free fatty acids, peroxide value, and induction time for oxidative stability by the Rancimat method have been compared for microwave‐ and conventionally baked puff pastries. The data indicate there were considerable changes in acidity, peroxide value, and Rancimat induction time in both microwave‐ and conventionally baked samples. Although the content of saturated fatty acid such as palmitic and stearic and the ratio of saturated to unsaturated fatty acids did not change significantly, an apparent increase was determined in trans oleic acid levels by both baking methods. In addition, a significant decrease in linoleic acid content of the samples was found by microwave baking.
Water‐hexane sorption in sunflower meals
Authors: Cardarelli D. A. , Mattea M. A. , Crapiste G. H.
Published: November 2006

Sorption equilibria of water and hexane in sunflower meals were determined at atmospheric pressure and temperatures from 50 to 95°C. Adsorption‐desorption experiments, for both individual vapors and water‐hexane mixtures, were carried out using a dynamic technique based on gravimetric measurements with a Cahn electrobalance. The isotherms were fitted to the Guggenheim‐Anderson‐deBoer sorption equation, and the heat of sorption was evaluated from experimental results. In the range of temperatures investigated, water sorption was several times higher than hexane sorption, the differences increasing with solvent activity. The net heat of sorption that resulted was significantly higher for hexane than for water. Water sorption isotherms were slightly affected by temperature, especially at water activities greater than 0.6. Some hysteresis was observed in water sorption at 50°C, but it was practically negligible at higher temperatures. Hexane previously adsorbed in the meal did not affect significantly the sorption of water. On the contrary, water previously adsorbed in the meal increased the amount of adsorbed hexane.
Quantitative structure‐capillary column gas chromatographic retention time relationships for natural sterols (trimethylsilyl ethers) from olive oil
Authors: Acuña‐Cueva Rocío , Hueso‐Ureña Francisco , Illán Cabeza Nuria A. , Jiménez‐Pulido Sonia B. , Moreno‐Carretero Miguel N. , Martínez Martos José M.
Published: November 2006

A study of the relationship between the capillary column gas chromatographic retention times on two different columns (SE‐54 and SE‐52) for a group of trimethylsilyl ethers derived from 16 natural sterols found in olive oil and an initial set of 60 molecular descriptors was made. Three kinds of molecular descriptors were used: conventional, topological, and quantumchemical parameters. By using multivariable regression, two empirical functions for each column were obtained, which were selected on the basis of their respective statistical parameters. The first model relates the retention index with the quantum‐chemical descriptors and the second with both topological and conventional descriptors. In all cases, the correlation coefficients of the empirical functions were higher than 0.9880, and the mean relative errors range between 2.88 and 3.24%. In any case, both models could be used, although the second model could be more useful and preferable because it has higher R2 values and a lower standard error percentage, giving slightly more exact results.
Determination of trace amounts of fatty acids in edible oils by capillary gas‐liquid chromatography
Authors: Buchgraber M. , Ulberth F. , Anklam E.
Published: November 2006

The effect of using different gas‐liquid chromatography (GLC) hardware to quantify low concentrations of fatty acids was studies. A fused‐silica capillary column was operated in two different chromatographs (A and B) that were interfaced to three different chromatographic data systems to process the flame‐ionization detector signals (systems A, B1, and B2). A test routine was developed that allowed the proper selection of peak processing parameters for the automatic recognition and integration of fatty acids occurring at trace levels. However, agreement of analytical results between the three analytical systems was not satisfactory; components at concentrations <0.10 g/100 g could not be quantified with high reliability, although the same capillary column and identical sample solutions were used (quasi‐repeatability conditions). Even for major fatty acids, deviations up to 1.0 g/100 g were noted, which could only be attributed to the use of different GLC hardware. Attention should be paid to these technical restrictions when formulating product specifications based on fatty acid profile parameters.
Characterization of farmed and wild salmon (Salmo salar) by a combined use of compositional and isotopic analyses
Authors: Aursand M. , Mabon F. , Martin G. J.
Published: November 2006

Gas chromatography, isotope ratio mass spectrometry, and high‐resolution 2H site‐specific natural isotope fractionation/nuclear magnetic resonance spectroscopy have been used to study the different kinds of fish oils and lipids extracted from muscle of wild and farmed salmon (Norway, Scotland). A statistical analysis of the fatty acid compositions, overall 2H and 13C isotope ratios, and molar fractions of the isotopomeric deuterium clusters was carried out to select the most efficient variables for distinguishing the different groups of salmons and fishes studied. A classification analysis based on four fatty acid compositions, three deuterium molar fractions, and the overall (D/H)tot isotope ratio of fish oils completely assings the oils to the right group.
Nuclear magnetic resonance spectroscopy and reversed‐phase high‐performance liquid chromatography of peracetylated digalactosyldiacylglycerols
Authors: Bergqvist Magnus , Holmbäck Jan
Published: November 2006

A simple method for the peracetylation of digalactosyldiacylglycerols is described. The peracetylated compounds were isolated by thin‐layer chromatography and subjected to nuclear magnetic resonance spectroscopy for structure elucidation. The proton signals at acetylated sites are shifted downfield compared to the nonderivatized compounds, resulting in improved resolution. The peracetylated compounds were also subjected to molecular species analysis by reversed‐phase high‐performance liquid chromatography. The chromatography behavior of the peracetylated compounds was similar to that of triacylglycerols, displaying narrow and symmetrical peaks yielding a highly resolved molecular species profile.
Synthesis, purification, and characterization of structured lipids produced from chicken fat
Authors: Lee Ki‐Teak , Foglia Thomas A.
Published: November 2006

A structured lipid (SL) was synthesized enzymatically from chicken fat by incorporating a medium‐chain length fatty acid (caprylic acid) into chicken fat triacylglycerols. Carica papaya latex was used as the biocatalyst. The optimal substrate mole ratio found was 1∶2 (chicken fat fatty acids/caprylic acid). At this ratio of reactants, the incorporation of caprylic acid (C8∶0) at 65°C was 23.4 mol%, whereas at 55°C the incorporation of caprylic acid was 17.6 mol%. A packed‐bed column bioreactor was designed for the synthesis of SL from chicken fat. In using ground crude C. papaya latex (aw<0.1), 7.1 mol% of caprylic acid was incorporated into the chicken fat triacylglycerols after 117 min of reactor residence time. After purification of the SL, the acyl positional distribution of fatty acids on the glycerol backbone was determined by 13C nuclear magnetic resonance (NMR) spectroscopy. From the NMR spectrum of the SL, it was determined that saturated fatty acyl residues at the 1,3‐positions of the SL triacylglycerols increased to 62% over that of the starting chicken fat triacylglycerols, suggesting that caprylic acid was preferentially incorporated at the 1,3‐positions. In addition, differential scanning calorimetry thermograms were obtained to compare the crystallization characteristics of the starting chicken fat with the SL prepared from it.
A new spectrophotometric method for the rapid assessment of deep frying oil quality
Authors: Xu Xin‐Qing
Published: November 2006

A new and quick spectrophotometric method was developed to assess deep‐frying oil quality. The scanned spectrophotometric curves of the frying oil samples from 350 and 650 nm wavelength changed systematically with the duration of deep frying. The absorbances of the frying oil samples, especially those measured at 490 nm, increased significantly during frying and were significantly correlated to frying time (r ≥0.95, P<0.001). There was a strong correlation between the absorbances of a set of oil samples taken from 0 to 80 h of deep frying and total polar compound contents in the same set of oil samples analyzed using the American Oil Chemists' Society official method (r=0.974, P<0.001). The equation for conversion of the absorbances to total polar compound contents is y=−2.7865x2 +23.782x+1.0309. The absorbances of 10 different types of frying oils with samples taken from 0 to 80 h of deep frying in duplicate were also strongly correlated to total polar compounds in the same oil samples (r=0.953, P<0.001, n=220). The results show that this method is fast, simple, convenient, and reliable.
Precision and accuracy in the color specification of virgin olive oils from the bromthymol blue method
Authors: Melgosa M. , Prez M. M. , Hita E. , Moyano M. J. , Alba J. , Heredia F. J.
Published: November 2006

Twenty experienced observers with nondefective color vision judged 27 virgin olive oil samples within an acceptable color range, using the bromthymol blue (BTB) method, under controlled observation conditions (daylight source with a correlated color temperature of 6500 K, and standard gray back‐ground). On the average, 44.8% of the observers agreed in their selections of the BTB standard solution matching a given oil sample, and this percentage increased to 88.2% considering ±one step in the two dimensions (pH and concentration) of the BTB scale. On the average, the lowest color difference between oil samples and available BTB solutions was 6.6 Commission Internationale de l'Éclairage 1976‐(L*a*b*) (CIELAB) units, but this color difference was approximately two times greater for the color difference between oil samples and BTB solutions selected by our observers. The colors of the BTB standard solutions in the CIELAB space are not uniformly distributed, and thus one step in pH or concentration is equivalent to CIELAB color differences varying in a wide range (1.7–13.5 and 1.7–26.3 CIELAB units, respectively). From these values, indicating low precision, accuracy, and uniformity, some suggestions are made for future improvements of the current BTB method.
Effects of β‐carotene and lycopene thermal degradation products on the oxidative stability of soybean oil
Authors: Steenson Donald F. , Min David B.
Published: November 2006

The relative oxidative stability of soybean oil samples containing either thermally degraded β‐carotene or lycopene was determined by measuring peroxide value (PV) and headspace oxygen depletion (HOD) every 4 h for 24 h. Sobyean oil samples containing 50 ppm degraded β‐carotene that were stored in the dark at 60°C displayed significantly (P<0.01) higher HOD values compared with controls. Lycopene degradation products (50 ppm) in soybean oil significantly (P<0.05) decreased HOD of samples when stored in the dark. PV and HOD values for samples containing 50 ppm of either β‐carotene or lycopene degradation products stored under lighted conditions did not differ significantly from controls (P<0.05). However, soybean oil samples containing 50 ppm of unheated, all‐trans β‐carotene or lycopene stored under light showed significantly lower PV and HOD values than controls (P<0.01). These results indicated that during autoxidation of soybean oil held in the dark, β‐carotene thermal degradation products acted as a prooxidant, while thermally degraded lycopene displayed antioxidant activity in similar soybean oil systems. In addition, β‐carotene and lycopene degradation products exposed to singlet oxygen oxidation under light did not increase or decrease the oxidative stability of their respective soybean oil samples.
Oil stability index correlated with sensory determination of oxidative stability in light‐exposed soybean oil
Authors: Coppin Elizabeth A. , Pike Oscar A.
Published: November 2006

Validity of the oil stability index (OSI) as an accelerated test of oxidative stability has been questioned because of its high holding temperature, 110°C, which may cause reactions that would not occur at lower temperatures. The purpose of this study was to characterize the usefulness of OSI as an accelerated oxidative stability test for oil of varying metal catalyst content by correlating OSI with the sensory induction period of light‐exposed soybean oil. Five 400‐g aliquots of soybean oil were placed in Erlenmeyer flasks and treated with increasing levels of a metal pro‐oxidant, Cu2+ 2‐ethylhexanoate. Pro‐oxidant concentration ranged from 0 to 3.13×10−5 M. Five‐gram aliquots were taken from duplicate flasks and immediately tested using the Oxidative Stability Instrument. Heating block temperature was 110°C. Sample flasks were then exposed to 800 footcandles of light and held at ambient temperature for 3 wk. One‐gram aliquots were regularly withdrawn and evaluated for rancidity by 10 trained panelists to determine the sensory induction period of each sample. Aliquots were also taken to determine OSI of light‐exposed oil samples. Sensory induction periods were correlated with OSI, resulting in a squared partial correlation coefficient (r2) of 0.920. The r2 for OSI of light‐exposed oil samples ranged from 0.897 to 0.979. OSI appears to be an acceptable accelerated method for measuring the oxidative stability of light‐exposed soybean oil that varies in metal catalyst content.
Production of margarine fats by enzymatic interesterification with silica‐granulated Thermomyces lanuginosa lipase in a large‐scale study
Authors: Zhang Hong , Xu Xuebing , Nilsson Jörgen , Mu Huiling , Adler‐Nissen Jens , Høy Carl‐Erik
Published: November 2006

Interesterification of a blend of palm stearin and coconut oil (75∶25, w/w), catalyzed by an immobilized Thermomyces lanuginosa lipase by silica granulation, Lipozyme TL IM, was studied for production of margarine fats in a 1‐ or 300‐kg pilot‐scale batch‐stirred tank reactor. Parameters and reusability were investigated. The comparison was carried out between enzymatic and chemical interesterified products. Experimentally, Lipozyme TL IM had similar activity to Lipozyme IM for the interesterification of the blend. Within the range of 55–80°C, temperature had little influence on the degree of interesterification for 6‐h reaction, but it had slight impact on the content of free fatty acids (FFA). Drying of Lipozyme TL IM from water content 6 to 3% did not affect its activity, whereas it greatly reduced FFA and diacylglycerol contents in the products. Lipozyme TL IM was stable in the 1‐kg scale reactor at least for 11 batches and the 300‐kg pilot‐scale reactor at least for nine batches. Due to regiospecificity of the lipase (sn‐1,3 specific), enzymatically interesterified products had different fatty acid distribution at sn‐2 position from the chemically randomized products, implying the potential nutritional benefits of the new technology.
Effect of alleles governing 16:0 concentration on glycerolipid composition in developing soybeans
Authors: Wilson R. F. , Marquardt T. C. , Novitzky W. P. , Burton J. W. , Wilcox J. R. , Dewey R. E.
Published: November 2006

Soybean [Glycine max (L.) Merr.] oil typically contains 11% palmitic acid, but germplasm with recessive alleles at Fap gene loci exhibit from less than 4% to about 35% 16:0, Although these alleles are used to develop new cultivars, little is known about how they influence palmitic acid concentration. One theory suggests that fap alleles may mediate differences in triacylglycerol composition through genetic effects on the activity or substrate specificity of acyltransferases, such as diacylglycerol acyltransferase (EC 2.3.1.20). Based on logistic function analysis of developing seed, differences in fag allele expression are evident in the rate of palmitic acid accumulation in triacylglycerol, with peak deposition near mid‐seed fill. Acetate saturation kinetics also reveal a strong positive relation between the relative amount of de novo palmitic acid synthesis and the indigenous palmitic acid concentration in triacylglycerol among fap genotypes. However, no differences appear in the kinetics of palmitoyl‐CoA metabolism in developing seed of these genotypes. Therefore, the fap alleles apparently do not encode or regulate the activities of glycerolipid acyltransferase enzymes. Rather, major genetic effects on triacylglycerol composition accrue through regulation of palmitic acid production in the plastids of developing soybean cotyledons.
Melting behavior of blends of milk fat with hydrogenated coconut and cottonseed oils
Authors: Shen Z. , Birkett A. , Augustin M. A. , Dungey S. , Versteeg C.
Published: November 2006

The melting behavior of milk fat, hydrogenated coconut and cottonseed oils, and blends of these oils was examined by nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). Solid fat profiles showed that the solid fat contents (SFC) of all blends were close to the weighted averages of the oil components at temperatures below 15°C. However, from 15 to 25°C, blends of milk fat with hydrogenated coconut oils exhibited SFC lower than those of the weighted averages of the oil components by up to 10% less solid fat. Also from 25 to 35°C, in blends of milk fat with hydrogenated cottonseed oils, the SFC were lower than the weighted averages of the original fats. DSC measurements gave higher SFC values than those by NMR. DSC analysis showed that the temperatures of crystallization peaks were lower than those of melting peaks for milk fat, hydrogenated coconut oil, and their blends, indicating that there was considerable hysteresis between the melting and cooling curves. The absence of strong eutectic effects in these blends suggested that blends of milk fat with these hydrogenated vegetable oils had compatible polymorphs in their solid phases. This allowed prediction of melting behavior of milk‐fat blends with the above oils by simple arithmetic when the SFC of the individual oils and their interaction effects were considered.
Synthesis of δ‐eicosanolactone and δ‐docosanolactone directly from meadowfoam oil
Authors: Isbell Terry A. , Cermak Steven C.
Published: November 2006

δ‐Eicosanolactone and δ‐docosanolactone were synthesized directly from the triacylglycerides of meadowfoam (Limnanthes) oil. Perchloric and sulfuric acids were used in stoichiometric quantities (0.5–4.0 mol equiv) to cyclize triglyceride to δ‐lactone. When the reactions were run in the absence of solvent at 40°C, δ‐lactone yields ranged from 17–75% where δ/γ ratios ranged from 6∶1 to 10.4.∶1. Sulfuric and perchloric acids gave similar yields for their individually optimized reactions. Perchloric acid‐catalyzed reactions required less acid to produce similar amounts of δ‐lactone (HClO4 at 2.0 mol equiv gave 73% yield vs. H2SO4, which gave 75% yield at 2.5 mol equiv). The use of polar nonparticipating solvents during the reaction had little impact on δ‐lactone formation or δ/γ ratio. Higher perchoric acid concentrations provided higher δ‐lactone yields with δ/γ ratios remaining nearly constant. The effect of sulfuric acid on δ‐lactone yield and δ/γ ratio was more direct; higher acid concentration improved, both. Both crystallization and short path distillation improved δ‐lactone quality but short path distillation gave, higher recovered yields. The δ‐lactones were converted to their corresponding 5‐hydroxy acids in the same reaction vessel, separated, and cyclized back to δ‐lactones upon heating under vacuum. This provided a convenient method for δ‐lactone purification.
Optimizing reaction parameters for the enzymatic synthesis of epoxidized oleic acid with oat seed peroxygenase
Authors: Piazza George J. , Foglia Thomas A. , Nuñez Alberto
Published: November 2006

Peroxygenase is a plant enzyme that catalyzes the oxidation of a double bond to an epoxide in a stereospecific and enantiofacially selective manner. A microsomal fraction containing peroxygenase was prepared from oat (Avena sativa) seeds and the enzyme immobilized onto a hydrophobic membrane. The enzymatic activity of the immobilized preparation was assayed in 1 h by measuring epoxidation of sodium oleate (5 mg) in buffer‐surfactant mixtures. The pH optimum of the reaction was 7.5 when t‐butyl hydroperoxide was the oxidant and 5.5 when hydrogen peroxide was the oxidant. With t‐butyl hydroperoxide as oxidant the immobilized enzyme showed increasing activity to 65°C. The temperature profile with hydrogen peroxide was flatter, although activity was also retained to 65°C. In 1 h reactions at 25°C at their respective optimal pH values, t‐butyl hydroperoxide and hydrogen peroxide promoted epoxide formation at the same rate. Larger‐scale reactions were conducted using a 20‐fold increase in sodium oleate (to 100 mg). Reaction time was lengthened to 24 h. At optimized levels of t‐butyl hydroperoxide 80% conversion to epoxide was achieved. With hydrogen peroxide only a 33% yield of epoxide was obtained, which indicates that hydrogen peroxide may deactivate peroxygenase.
Production of arachidonic acid by filamentous fungus, Mortierella alliacea strain YN‐15
Authors: Aki Tsunehiro , Nagahata Yumiko , Ishihara Katsuyuki , Tanaka Yoshio , Morinaga Tsutomu , Higashiyama Kenichi , Akimoto Kengo , Fujikawa Shigeaki , Kawamoto Seiji , Shigeta Seiko , Ono Kazuhisa , Suzuki Osamu
Published: November 2006

A filamentous fungus producing significant levels of arachidonic acid (AA, C20∶4n−6) was isolated from a freshwater pond sample and assigned to the species Mortierella alliacea. This strain, YN‐15, accumulated AA mainly in the form of triglyceride in its mycelia. An optimized culture in 25 L of medium containing 12% glucose and 3% yeast extract yielded 46.1 g/L dry cell weight, 19.5 g/L total fatty acid, and 7.1 g/L AA by 7‐d cultivation in a 50‐L jar fermenter. Assimilation of soluble starch by YN‐15 was notably enhanced by the addition of oleic acid, soybean oil, ammonium sulfate, or potassium phosphate to a starch‐based medium. Using starch as a main carbon source in the pre‐pilot scale cultivation improved the production of AA by up to 5.0 g/L. Mortierella alliacea strain YN‐15 is therefore a promising fungal isolate for industrial production of AA and other polyunsaturated fatty acids.
Transient heat conduction and hotspot development prediction in a flaking roll with revolving heat flux and convection boundary conditions
Authors: Singh P. P. , Maier D. E.
Published: November 2006

In the oilseed crushing industry, flaking rolls sometimes develop hotspots that cause high thermal stresses. Soybean flakes on contact with hotspots crumble to powder, which is unsuitable for oil extraction. Transient heat conduction equations with revolving boundary conditions were solved using the finite element method. Simulations demonstrated that hotspots arise due to heat flow in three dimensions from the source toward the roll ends and the curved surface. An estimated heat flux value of 56 kW/m2 yielded surface temperature values near observed values. Perturbations performed to the base values showed that a 10% increase in thermal conductivity caused a 6–8% reduction in peak thermal gradient, whereas a 20% increase in heat‐transfer coefficient caused less than 2% reduction in peak thermal gradient. Therefore, thermal conductivity is a more sensitive parameter affecting thermal gradients than the heat‐transfer coefficient. A small change in heat‐transfer coefficient caused by aspirating air through the flake outlet of the roll stands would not cause a significant reduction in temperature and thermal gradients in rolls. The higher thermal gradients observed near the outer surface of rolls suggest that casting rolls with subsurface layers of higher thermal conductivity would make rolls less prone to forming hotspots.
Cocoa‐butter long spacings and the memory effect
Authors: van Langevelde Arjen , Driessen René , Molleman Wim , Peschar René , Schenk Henk
Published: November 2006

Depending on the maximum temperature before cooling, cocoa butter recrystallizes in the β(V) and/or β(VI) phase. In order to obtain structural information on the seed material initiating this recrystallization process, experiments with cocoa butter were performed at a small‐angle X‐ray scattering station. Crystallization of cocoa butter at various crystallization temperatures provided long d‐spacing values (d>45 Å) that can be attributed to the polymorphic phases. From the recrystallization experiments it is concluded that the seeds initiating rapidstarting recrystallization have an 1,3‐distearoyl‐2‐oleoylglycerol‐dominated triple chain‐length packing. Furthermore, the β(VI) phase of cocoa butter seems to adopt a similar packing. The seed crystals that initiate the slow‐starting recrystallization and result in the β(V) phase are likely to be different from those giving the β(VI) phase.
Antioxidants from a heated histidine‐glucose model system. Investigation of the copper(II) binding ability
Authors: Bersuder P. , Hole M. , Smith G.
Published: November 2006

The metal binding ability of Maillard reaction products (MRP) was investigated by spectrophotometric monitoring for complex/chelate formation. In addition, the antioxidant activity of MRP, in the presence of Cu(II), was evaluated on a lipid model system consisting of sunflower seed oil/water (1∶2). Results from the Rancimat test indicated a significant decrease in pro‐oxidant ability of Cu(II) in the presence of MRP in contrast to histidine alone, whether heated or not. Results from the diphenylpicrylhydrazyl method showed that, in contrast to histidine (heated or not), the antiradical ability of MRP is reduced in the presence of Cu(II), but depends on the reaction time between MRP and Cu(II).
Molecular weight distribution and regioisomeric structure of triacylglycerols in some common human milk substitutes
Authors: Kurvinen J. ‐P. , Sjövall O. , Kallio H.
Published: November 2006

Triacylglycerol (TAG) molecular weight distribution and regioisomeric structure of selected molecular weight species in human milk and in 32 human milk substitutes was determined. Negative ion chemical ionization mass spectrometry was used to determine the molecular weight distribution and collisionally induced dissociation tandem mass spectrometry applied to identify the sn‐2 and sn‐1/3 positions of fatty acids in TAG. The main molecular weight species of human milk TAG in decreasing order of abundance were 52∶2, 52∶3, 52∶1, 54∶3, 50∶2, 50∶1, 54∶4, 48∶1, 54∶2, 48∶2, 46∶1, 52∶4, and 50∶3 (acyl carbon number/number of double bonds), constituting 83 mol% of total TAG molecular species. In human milk substitutes, the proportion of the corresponding molecular weight species varied from 33 to 87 mol%. The main TAG regioisomers within the molecular weight species 52∶2, 52∶3, and 50∶1 in human milk were 18∶1‐16∶0‐18∶1 (83 mol%), 18∶1‐16∶0‐18∶2 (83 mol%), and 18∶1‐16∶0‐16∶0 (80 mol%), respectively. In human milk substitutes, the corresponding proportions varied in a wide range of 0–82 mol%, 0–100 mol%, and 0–73 mol%, respectively. Although TAG structures in some human milk substitutes closely resembled those in human milk, the great variation among samples leads to the conclusion that it is still possible to improve the TAG composition in human milk substitutes by applying novel methods to synthesize structured TAG.