bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Initial Stresses and Wall Thickness on Wave Characteristics in Elastic Tubes
Authors: Demiray H. , Antar N.
Published: May 2007

Employing the theory of small deformations superimposed on large initial static deformations, the propagations of harmonic waves in an initially stressed thick elastic tube filled with a viscous fluid is studied. Due to variability of the coefficients of the resulting differential equation of the tube, the field equations are solved by a power series method. Utilizing the properly posed boundary conditions that characterize the reaction of fluid with the tube wall, the dispersion relation is obtained as a function of initial deformations and the geometrical characteristics. The dispersion equation is examined analytically, whenever it is possible, and numerically, and the results are depicted on some graphs. It is observed that wave speeds increase with thickness parameter.
On the Determination of the Solutions for the Kinetic State of Single‐Freedom Multi‐Body Systems with Friction
Authors: Klepp H. J.
Published: May 2007

A single‐freedom multi‐body system with determinate structure having friction‐affected sliders and hinges is considered. For the determination of the solutions of initial value problems the governing equations are put in the form of a system of linear algebraic equations having the absolute values of the friction forces as unknowns. The coefficients of these equations contain the signs of the unknown normal reactions, and the unknown friction torques are included in the right‐hand‐sides of these equations. With all possible sets of assumptions for the signs of the normal reactions and approaches of the friction torques these equations are solved, and the solutions, which are approaches of the friction forces, are selected. With these approaches of the friction forces new approaches of the friction torques can be established, which can be used for repeating the calculations, until the desired accuracy is reached. The determination of the accelerations and reaction forces of a five‐body system with three sliders and four hinges with this method evidenced advantages in comparison with pure iteration schemes.
The Use of Defect Correction for the Solution of Parabolic Singular Perturbation Problems
Authors: Hemker P. W. , Shishkin G. I. , Shishkina L. P.
Published: May 2007

We construct discrete approximations for a class of singularly perturbed boundary value problems, such as the Dirichlet problem for a parabolic differential equation, for which the coefficient multiplying the highest derivatives can take an arbitrarily small value from the interval (0, 1]. Discretisation errors for classical discrete methods depend on the value of this parameter and can be of a size comparable with the solution of the original problem. We describe how to construct special discrete methods for which the accuracy of the discrete solution does not depend on the value of the parameter, but only on the number of mesh points used. Moreover, using defect correction techniques, we construct a discrete method that yields a high order of accuracy with respect to the time variable. The approximation, obtained by this special method, converges in the discrete l∞‐norm to the true solution, independent of the small parameter. For a model problem we show results for our scheme and we compare them with results obtained by the classical method.
The Hermite Equation and the Generalised Laplace Transform
Authors: Deakin M. A. B.
Published: May 2007

The second order Laplace equation (i.e. the linear o.d.e. with linear coefficients) may be reduced to one of a number of standard forms. One of these is the Hermite equation which has hitherto been thought not to be treatable by the Laplace transform. This is true because the defining integral for that transform diverges in this case. However this problem does not arise with a generalised Laplace transform. This paper gives the detailed working out of the theory from this point of view, and in the process derives results for the parabolic cylinder functions; these derivations are simpler than the standard ones or else produce these (known) results in a somewhat different form.
An Interval Algorithm for Linear‐Nonlinear Coupled Systems
Authors: Ling Y.‐X.
Published: May 2007

In this paper an interval algorithm for linear‐nonlinear coupled systems is described, and the convergence of the interval sequence is proved. The algorithm is composed of two steps of lower dimensional calculations, for large or sparse problems it is an efficient method.
The Lifting Line Equation for a Curved Wing in Oscillatory Motion
Authors: Chiocchia G. , Tordella D. , Prössdorf S.
Published: May 2007

An unsteady linear lifting line method for the determination of the circulation and lift distribution along the span of a curved wing subject to harmonic small amplitude oscillations is presented. The method relies on the Pistolesi‐Weissinger 3/4‐chord steady lifting line theory and couples it to the unsteady theory developed by Possio for the motion of lifting surfaces. It leads to an integro‐differential equation of a modified Prandtl's type, where the unknown is the circulation. This equation has been carefully analysed in order to evidence all the singularities and to treat them in the most convenient way. The numerical procedure consists of a gaussian quadrature technique based on Chebyshev's polynomial approximation of the unknown function. The method has been appraised through the comparison of a number of solutions, pertaining to different wing configurations, with existing solutions based on lifting surface theory.
Mechanics of Multiphase Materials
Authors: Fischer F. D. , Werner E.
Published: May 2007

First the observation levels for materials are discussed. Then a material is modelled as a heterogeneous continuum consisting of grains, each of them being a tiny continuum in its turn. As demonstration material steel consisting of two phases is selected. In the case of duplex steel the material consists a priori of two phases at fixed volume fractions. Subsequently, the martensitic transformation in a Fe‐Ni steel is investigated as an example for a material with changing volume fractions of the phases. It is shown how continuum mechanics and thermodynamics can help to explain the some‐what unexpected deformation behavior of those materials.

Vorerst werden die verschiedenen Beobachtungsmaßstäbe für Werkstoffe erörtert. In der Folge wird ein Werkstoff als heterogenes Kontinuum im Sinne einer Ansammlung von Körnern betrachtet. Jedes Korn für sich stellt wiederum ein kleines Kontinuum dar. Als Demonstrationsmaterial wird Stahl ausgewählt, der aus zwei Phasen besteht. Im Falle des Duplexstahles besitzt das Material zwei Phasen mit fixer Volumsfraktion. Weiters wird die martensitische Umwandlung in einem Fe‐Ni‐Stahl behandelt, die zu einer veränderlichen Volumsfraktion der beiden Phasen führt. Es wird gezeigt, wie die Kontinuumsmechanik und Thermodynamik beitragen können, um das doch merkwürdige Verformungsverhalten dieser beiden Werkstoffe aufzuklären.
On the Localization and Computation of Zeros of Bessel Functions
Authors: Vrahatis M. N. , Grapsa T. N. , Ragos O. , Zafiropoulos F. A.
Published: May 2007

The topological degree of a continuous mapping is implemented for the calculation of the total number of the simple real zeros within any interval of the Bessel functions of first and second kind and their derivatives. A new algorithm, based on this implementation, is given for the localization and isolation of these zeros. Furthermore, a second algorithm is presented for their computation employing a modified bisection method. The only information required for this computation is the algebraic signs of function values. Moreover, lower and upper bounds of a zero can also be obtained.
On the Existence of Positive Solutions to a Three‐Point Boundary Value Problem for the One‐Dimensional p‐Laplacian
Authors: Wang J.‐Y. , Zheng D.‐W.
Published: May 2007

The existence of positive solutions to a three‐point boundary value problem for the one‐dimensional p‐Laplacian is proved by a simple application of a Fixed Point Theorem in cones due to Krasnoselskii and the Arzela‐Ascoli Theorem.
On Hybrid High Resolution Upwind Methods for Multicomponent Flows
Authors: Ivings M. J. , Causon D. M. , Toro E. F.
Published: May 2007

Shock capturing numerical methods expressed in terms of conservative variables produce erroneous solutions when applied to multicomponent flows. Numerical schemes expressed in terms of primitive variables are able to provide accurate results for non‐shocked multicomponent flows. An assessment of four hybrid primitive‐conservative upwind schemes is presented for the solution of multicomponent flows involving strong shock waves. The schemes used are the MUSCL‐Hancock scheme, the Weighted Average Flux scheme, and modified versions of the Generalised Riemann Problem, and Piecewise Linear Methods. These four hybrid schemes provide accurate solutions to such problems, and numerical experiments suggest that they converge. It is also shown that conservative methods may often provide satisfactory results when applied to multicomponent problems when the flow is dominated by strong shocks.
Scalar Wave Diffraction by a Rigid Cylindrical Rod of Finite Length with Impedance Ends
Authors: Büyükaksoy A. , Polat B.
Published: May 2007

A uniform asymptotic high frequency solution is presented for the problem of diffraction of plane harmonic sound waves by an acoustically rigid cylindrical rod of finite length with the ends characterized by the same surface impedance. This problem is described by a modified Wiener‐Hopf equation of the third kind and then solved approximately. The solution involves two infinite sets of constants satisfying two infinite systems of linear algebraic equations. Numerical solutions of these systems are obtained for various values of the parameters of the problem and their effects on the diffraction phenomenon are shown graphically.
The Dirichlet Problem for the 2‐D Helmholtz Equation in a Multiply Connected Domain with Cuts
Authors: Krutitskii P. A.
Published: May 2007

The Dirichlet problem for the dissipative Helmholtz equation in a connected plane region with cuts is studied. The existence of a classical solution is proved by potential theory. The problem is reduced to a Fredholm equation of second kind, which is uniquely solvable.
Hausdorff Dimension Estimates for Time‐Discrete Feedback Control Systems
Authors: Noack A.
Published: May 2007

We consider time‐discrete dynamical systems written as generalized feedback systems. Several results on the estimation of the Hausdorff dimension of negatively invariant sets of C1‐maps on Riemannian manifolds based on a theorem by Douady and Oesterlé are used to estimate the Hausdorff dimension of negatively invariant sets of discrete systems. In particular, conditions in the frequency domain are formulated. As a special class discrete systems acting on the cylinder are discussed.
On the Reconstruction of a Rigid Body in the Theory of Elasticity
Authors: Dassios G. , Rigou Z.
Published: May 2007

A method is proposed for the solution of the inverse scattering problem associated with the shape reconstruction of a 3‐D, star shaped, rigid scatterer in the theory of elasticity. The inversion procedure is based on the use of elastic Herglotz functions. A key point of the method is a basic connection formula associating the scattered field and the Herglotz function on the surface of the scatterer, with the corresponding scattering amplitudes and Herglotz kernels on the unit sphere. Analytical difficulties caused by the complexity of the spectral Navier operator were overpassed by embedding the vector elastic scattering problem into a dyadic scattering problem, which absorbs the dependence of the incident field upon the transverse polarization by considering a complete incident dyadic field. The actual elastic problem is then obtained by projecting the dyadic scattering problem into the particular polarization of the assumed incident field. The method, which for the scalar case has been developed by Colton and Monk, leads to an optimization scheme which is similar, but much more complicated, to the corresponding scheme in acoustics.
Interference of Mesoscopic Particles: Quantum–Classical Transition
Authors: Facchi P. , Yoneda T. , Pascazio S.
Published: May 2007

We analyze the double slit interference of a mesoscopic particle. We calculate the visibility of the interference pattern in the far field case, introduce a characteristic temperature that defines the onset to decoherence and scrutinize the conditions that must be satisfied for an interference experiment to be possible.
Two-Way Protocol with Imperfect Devices
Authors: Lucamarini Marco , Ceré Alessandro , Di Giuseppe Giovanni , Mancini Stefano , Vitali David , Tombesi Paolo
Published: May 2007

The security of a deterministic quantum scheme for communication, namely the LM05 [1], is studied in presence of a lossy channel under the assumption of imperfect generation and detection of single photons. It is shown that the scheme allows for a rate of distillable secure bits higher than that pertaining to BB84 [2]. We report on a first implementation of LM05 with weak pulses.
Stoichiometric determination of hydroperoxides in fats and oils by fourier transform infrared spectroscopy
Authors: Ma K. , van de Voort F. R. , Sedman J. , Ismail A. A.
Published: May 2007

A primary Fourier transform infrared (FTIR) spectroscopic method for the determination of peroxide value (PV) in edible oils was developed based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine oxide (TPPO). Accurate quantitation of the TPPO formed in this reaction by measurement of its intense absorption band at 542 cm−1 provides a simple means of determining PV. A calibration was developed with TPPO as the standard; its concentration, expressed in terms of PV, covered a range of 0–15 PV. The resulting calibration was linear over the analytical range and had a standard deviation of ±0.05 PV. A standardized analytical protocol was developed, consisting of adding ∼0.2 g of a 33% (w/w) stock solution of TPP in hexanol to ∼30 g of melted fat or oil, shaking the sample, and scanning it in a 100‐µm KCI IR transmission cell maintained at 80°C. The FTIR spectrometer was programmed in Visual Basic to automate scanning and quantitation, with the reaction/FTIR analysis taking about 2 min per sample. The method was validated by comparing the analytical results of the AOCS PV method to those of the automated FTIR procedure by using both oxidized oils and oils spiked with tert‐butyl hydroperoxide. The two methods correlated well. The reproducibility of the FTIR method was superior (±0.18) to that of the standard chemical method (±0.89 PV). The FTIR method is a significant improvement over the standard AOCS method in terms of analytical time and effort and avoids solvent and reagent disposal problems. Based on its simple stoichiometry, rapid and complete reaction, and the singular band that characterizes the end product, the TPP/TPPO reaction coupled with a programmable FTIR spectrometer provides a rapid and efficient means of determining PV that is especially suited for routine quality control applications in the fats and oils industry.
Upgrading the AOCS infrared trans method for analysis of neat fats and oils by fourier transform infrared spectroscopy
Authors: Sedman J. , van de Voort F. R. , Ismail A. A.
Published: May 2007

An automated protocol for the direct, rapid determination of isolated trans content of neat fats and oils by Fourier transform infrared (FTIR) spectroscopy was devised, based on a simple modification of the standard AOCS trans method, eliminating the use of CS2 and methylation of low trans samples. Through the use of a commercially available, heated transmission flow cell, designed specifically for the analysis of neat fats and oils, a calibration (0–50%) was devised with trielaidin spiked into a certified, trans‐free soybean oil. The single‐beam spectra of the calibration standards were ratioed against the single‐beam spectrum of the base oil, eliminating the spectral interference caused by underlying triglyceride absorptions, facilitating direct peak height measurements as per the AOCS IR trans method. The spectrometer was preprogrammed in Visual Basic to carry out all spectral manipulations, measurements, and calculations to produce trans results directly as well as to provide the operator with a simple interface to work from. The derived calibration was incorporated into the software package, obviating the need for further calibration because the program includes an automatic recalibration/standardization routine that automatically compensates for differences in optical characteristics between instruments, instrument drift over time, and cell wear. The modified AOCS FTIR analytical package was evaluated with Smalley check samples for repeatability, reproducibility, and accuracy, producing SD of ± 0.07, 0.13, and 0.70 trans, respectively, the FTIR predictions being linearly related to the Smalley means (r=0.999; SD=± 0.46), and well within one SD of the Smalley sample means. Calibration transfer was assessed by implementing the calibration on a second instrument and reanalyzing the Smalley check samples in cells of two different pathlengths (25‐ and 50‐µm). There were no statistically significant differences between the FTIR trans predictions obtained for the Smalley samples from the two instruments and two cells, indicating that the software was able to adjust the calibrations to compensate for differences in instrument response and cell pathlength. The FTIR isolated trans analysis protocol developed by the McGill IR Group has the benefit of being based on the principles of an AOCS‐approved method, matches its accuracy, and allows the analysis to be performed on both neat fats and oils, producing trans predictions in less than 2 min per sample. It is suggested that this integrated approach to trans analysis, which requires a minimum level of sample manipulation and operator skill, be considered as a modification of the proposed Recommended Practice CD14b‐95.
Effect of feeding muscovy ducklings different protein sources: Performance, θ‐3 fatty acid contents, and acceptability of their tissues
Authors: El‐Deek Ahmed A. , Barakat Mona O. , Attia Youssef A. , El‐Sebeay Ashraf S.
Published: May 2007

One hundred Muscovy ducklings, 5‐wk‐old, from each gender were assigned to five dietary treatments. Each treatment of each sex contained two replicates of 10 ducklings each. Ducks were fed, from 4–9 wk of age, five isonitrogenous diets that differed in protein source, i.e., commercial protein concentrate (CPC), soybean meal, meat meal (MM), herring fish meal (HFM), and mixed herring fish and meat meals (HFM + MM). At the end of the experiment, four ducks per treatment were slaughtered for carcass evaluation and the fatty acid profiles of their meat, adipose tissue, and plasma. Final body weight of both sexes showed no difference among protein sources, although males fed CPC or MM diets had the largest weight gain. No differences in feed consumption and conversion between sexes were shown, although differences in θ‐3 fatty acid consumption due to protein source were significant. Feeding fish meal reduced the sensory acceptance of meat, whereas the plant protein diet improved it. Total lipid and cholesterol contents of the meat of males showed no differences between protein sources. Correlation between θ‐3 fatty acid consumption and plasma cholesterol was negative (r=0.91; P=0.03). Moreover, correlation between plasma cholesterol and plasma lipid was positive (r=0.97; P=0.01). Feeding fish meal enriched total unsaturated fatty acid of adipose tissues, θ‐3 fatty acid of adipose and meat tissues, and total unsaturated fatty acid of thigh meat. Total unsaturated fatty acid and θ‐3 fatty acid of blood plasma from females were also enriched by feeding fish meal‐containing diets.
Lipids and biopackaging
Authors: Callegarin Francesca , Quezada Gallo Jesus‐Alberto , Debeaufort Frédéric , Voilley Andrée
Published: May 2007

Packaging is important to preserve food quality. It is a barrier to water vapor, gas, aroma, and solute migration between the food and the environment. With the recent increase in ecological consciousness, research has turned toward finding biodegradable materials. The different kinds of biopackaging are discussed with special focus on edible films. The aim of this review is to focus on the influence of lipids used in edible films, mainly for their efficiency as water‐vapor barriers. The structure, degree of saturation, chainlength, physical state, shape and dimension of crystals, and distribution of lipids into the film influence the functional properties of the film. In general, the performance of edible films is lower than that of synthetic films, but their main advantage is to be easily, fully, and rapidly biodegradable.
Viscosities of fatty acids, triglycerides, and their binary mixtures
Authors: Valeri Daniella , Meirelles Antonio J. A.
Published: May 2007

Viscosity data have been obtained as a function of temperature for seven fatty acids (pelargonic, capric, lauric, myristic, palmitic, stearic, and oleic) and four triglycerides (tricaprilin, tripalmitin, tristearin, and triolein) and their binary mixtures at temperatures from above their melting points to 90°C. The viscosity measurements were performed by using Cannon Fenske glass capillary kinematic viscometers. Modified versions of the Andrade equation were used to correlate the kinematic viscosities of pure fatty acids and pure triglycerides. The MacAllister method was used for their binary mixtures. The correlation constants are valuable for designing or evaluating chemical process equipment, such as heat exchangers, reactors, distillation columns, and process piping.
Offset printing inks based on rapeseed oil and sunflower oil. Part II: Varnish and ink formulation
Authors: Sabin Pascale , Benjelloun‐Mlayah Bouchra , Delmas Michel
Published: May 2007

Two sets of variable oil length, alkyd resins modified by sunflower oil (SOA) and by rapeseed oil (ROA), were evaluated in offset formulations with mineral oils as diluent. The more suitable alkyds for this kind of application were determined. In a second experiment, hydrocarbon solvents were substituted by the fatty acid methyl esters derived from rapeseed oil or sunflower oil to produce ecologically friendly offset printing inks. Finally, the ROA and the SOA were associated with the methyl esters derived from the same vegetable oil. New properties of the varnishes composed of a vegetable diluent were evaluated. The quickset formulations with the methyl esters do not need important modifications, as opposed to the heatset formulations.
Esterification patterns of lipases for synthesizing tricaproylglycerols in organic solvent
Authors: Kwon Dae Young , Song Hyo Nam , Yoon Suk Hoo
Published: May 2007

To investigate the synthetic patterns of triglyceride (triacylglycerol) by lipases in organic solvent, esterification patterns of triglyceride, diglyceride, and monoglyceride were monitored at various reaction times with 10 lipases. As a model study, tricaprin was synthesized from glycerol and capric acids (C10:0) in isooctane. Lipases that were known to give nonspecific hydrolysis in aqueous solvent, such as lipase from Candida cylindracea, Lipase OF‐360 (from C. rugosa), and Lipase MY (C. rugosa) showed nonspecific synthesis of tricaprin in organic solvent (Group I). There are two groups for esterifying trigly cerides in organic solvent with 1,3‐specific lipases: one consists of the lipases from Rhizomucor miehei, Pseudomonas aeruginosa (Lipase PS), and Chromobacterium viscosum (Lipase CV) (Group II), and another (Group III) is represented by Lipase AP (Aspergillus niger), Lipase FAP‐15 (Rhizopus javanicus), and Lipase D (R. delemar). Although both groups showed 1,3‐specific hydrolysis in aqueous solvent, Group III has stricter 1,3‐specificity for the synthesis of tricaprin from dicaprin.
Degradation of α‐linolenic acid during heating
Authors: Hénon G. , Kemény Zs. , Recseg K. , Zwobada F. , Kövári K.
Published: May 2007

Degummed bleached rapeseed oil was heated at 210, 220, and 230°C for up to 86 h under reduced pressure with nitrogen stripping. No significant change of total linoleic acid content was found, but a decrease of the total linolenic acid content was observed under extreme conditions. The degradation rate of linolenic acid is described as a function of heating time and operating temperature. Linolenic acid degradation can be predicted for any set of conditions by the established model. No significant degradation of linolenic acid can occur under standard deodorization conditions.
Fatty methyl ester hydrogenation to fatty alcohol part I: Correlation between catalyst properties and activity/selectivity
Authors: Rieke Ross D. , Thakur Deepak S. , Roberts Brian D. , White Geoffrey T.
Published: May 2007

Fatty alcohols, derived from natural sources, are commercially produced by hydrogenation of fatty acids or methyl esters in slurry‐phase or fixed‐bed reactors. One slurry‐phase hydrogenation of methyl ester process flows methyl esters and powdered copper chromite catalyst into tubular reactors under high hydrogen pressure and elevated temperature. In the present investigation, slurry‐phase hydrogenations of C12 methyl ester were carried out in semi‐batch reactions at nonoptimal conditions (i.e., low hydrogen pressure and elevated temperature). These conditions were used to accentuate the host of side reactions that occur during the hydrogenation. Some 14 side reaction routes are outlined. As an extension of this study, copper chromite catalyst was produced under a number of varying calcination temperatures. Differences in catalytic activity and selectivity were determined by closely following side reaction products. Both activity and selectivity correlate well with the crystallinity of the copper chromite surface; they increase with decreasing crystallinity. The ability to follow the wide variety of side reactions may well provide an additional tool for the optimized design of hydrogenation catalysts.
Effect of repeated heating on thermal behavior of crude palm oil
Authors: Haryati T. , Che Man Y. B. , Swe P. Z.
Published: May 2007

Thermal behavior of crude palm oil (CPO) is important to determine the optimal fractionation process and product yield. In this study, the effects of repeated heating on thermal behavior of CPO were examined by differential scanning calorimetry. CPO was heated at 80°C for 5 min, and heating was repeated five times to simulate the common conditions experienced by an oil before reaching the refinery. The result revealed that the thermal behavior of CPO changed after heating. The change, however, occurred only in the behavior of the high‐melting stearin peak but not in the low‐melting olein peak. Overheating split the stearin peak at 17.30°C to two peaks at 18.88 and 17.30°C and formed a new peak at 11.28°C. Apparently, a new substance has been synthesized.
Glycerolysis of fats and methyl esters
Authors: Noureddini H. , Medikonduru V.
Published: May 2007

The glycerolysis of methyl esters and triglycerides with crude glycerol, a coproduct from the transesterification of triglycerides, was studied. Three procedures were followed for this conversion. The first procedure was a one‐step glycerolysis with methyl esters. The second procedure was a two‐step process. This procedure involved an initial partial glycerolysis with methyl esters, followed by fat glycerolysis. The third procedure was a simultaneous glycerolysis with methyl esters and triglycerides. In the glycerolysis with methyl esters, the removal of methanol is vital to the production of mono‐ and diglycerides. Methanol was removed either by drawing vacuum on the reactor or by stripping methanol out by means of an inert carrier gas (nitrogen). Different molar ratios of methyl esters to glycerol were tested in the first two processes. At low concentration of methyl esters, total conversion of methyl esters to mono‐ and diglycerides was achieved. As the concentration of methyl esters was increased, the conversion of methyl esters to mono‐ and diglycerides was decreased. Furthermore, the ratio of mono‐ to diglycerides was also higher at lower concentrations of methyl esters. The conversion of triglycerides in the two‐step process with crude glycerol was similar to a one‐step fat glycerolysis with pure glycerol. The composition of different components and the ratio of mono‐ to diglycerides were also comparable.
Use of soy protein concentrates and lecithin products in diets fed to coho and atlantic salmon
Authors: Brown P. B. , Wilson K. A. , Hodgin Y. , Stanley J. D.
Published: May 2007

Aquacultural production is increasing in most parts of the world, establishing new and rapidly growing markets for various oil products. One of the more interesting nutritional requirements for aquatic animals is lecithin or phosphatidylcholine. In this paper, lecithin in aquaculture is reviewed with emphasis on freshwater fish and crayfish. Further, new data on use of lecithin and two soy protein concentrates in diets fed to coho and Atlantic salmon are presented. Juvenile coho and Atlantic salmon were fed either solvent‐extracted soybean meal (SBM) or Promocalf® at 30% of the diet, Promoveal® at 10, 20 or 30% of the diet, or one of three new lecithin products at a constant level of 3% of the diet. Juvenile coho salmon fed SBM, Promocalf®, or Promoveal® at 30% of the diet exhibited depressed weight gain and an elevated feed conversion ratio (FCR) compared to fish fed a positive control diet. Fish fed 10 or 20% Promoveal® had similar weight gain and FCR compared to fish fed the control diet. Coho salmon fed either of the three lecithin products (Aqualipid®, Blendmax®, or Centrol®) had similar weight gains and FCR values compared to fish fed the control diet. Whole‐body proximate components were not as responsive to dietary treatments as weight gain and FCR data. Juvenile Atlantic salmon exhibited depressed weight gain only when fed 30% Promocalf® and all three lecithin products. Further, whole‐body crude protein concentrations in fish fed the three lecithin products were depressed.
Effect of fatty acid composition of phospholipids on their antioxidant properties and activity index
Authors: Nwosu Chigozie Victor , Boyd Leon C. , Sheldon Brian
Published: May 2007

Various phospholipids may act as antioxidants or prooxidants. This study investigated the effects of three phospholipid classes and their fatty acid composition on antioxidant activity. Antioxidant properties of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine from salmon and menhaden oil were measured by oxidation induction time. An antioxidant activity index was determined in these systems with the Rancimat 617. Fatty acid profiles of the individual phospholipids and total oils were determined by gas‐liquid chromatography before and after oxidation. The index was significantly (P<0.05) influenced by the headgroup and fatty acid composition of the phospholipid. Lipids with a choline headgroup had oxidation induction times greater than 60 h in the salmon oil system. The choline‐containing phospholipid also offered better (P<0.05) protection from oxidation to the n‐3 and total polyunsaturated fatty acids in salmon oil. Phospholipids containing more saturated fatty acids had longer oxidation induction times (>84 h) and higher antioxidant index (>9). Chainlength of the fatty acids may have contributed to the observed index, as phospholipids with longer chains (i.e., C18 and above) had longer oxidation induction times. Phospholipids tested in this study had little or no antioxidant activity in menhaden oil, nor did they offer protection to n‐3 or total polyunsaturated fatty acids in this oil. These findings suggest that fatty acid profiles of individual oils may influence the antioxidant index of each phospholipid.
Oxidative stabilities of soybean oils with elevated palmitate and reduced linolenate contents
Authors: Shen Nuo , Fehr Walter , Johnson Lawrence , White Pamela
Published: May 2007

Oils from soybean lines, developed to contain different amounts of palmitate (16:0) and linolenate (18:3), were evaluated for oxidative stability. Oils were extracted in the laboratory from the soybean seeds and refined, bleached, and deodorized. Two replications, separated at the point of conditioning, were evaluated for each genotype, including Hardin 91 (normal beans), P9322 (10.6% 16:0 and <2.6% 18:3), A91‐282036 (26.3% 16:0 and 9.8% 18:3), and HPLL (23.2% 16:0 and 3.5 % 18:3). Elevating 16:0 and/or lowering 18:3 increased the oxidative stability of soybean oils as measured by peroxide values. Soybean oils with elevated 16:0 had higher solidification temperatures than did oils with normal 16:0 content, and soybean oils with low 18:3 content had higher solidification temperatures than did oils with normal 18:3 contents.
The role of silica gel in lipase‐catalyzed esterification reactions of high‐polar substrates
Authors: Castillo Edmundo , Dossat Valérie , Marty Alain , Condoret J. Stéphane , Combes Didier
Published: May 2007

The crucial role of silica gel in lipase‐catalyzed esterification reactions using adsorbed high‐polar substates was established. It was found that in these kinds of reactions, the presence of silica gel‐adsorbed substrates did not alter the kinetic mechanisms of the synthesis of acylglycerides but improved significantly the conversion yields. An explanation for the critical role of silica gel in these kinds of reactions was proposed whereby the silica gel behaves as a “polar substrate reservoir” and plays a protective role for the immobilized enzyme avoiding its blockage. In this way it was shown that the use of silica gel facilitates reactions at high glycerol concentrations without alteration of reaction rates or conversion yields. It also was demonstrated that highly hydrophilic polyols enhanced blockage of the enzyme. The importance of the presence of an organic solvent in the reaction medium was shown to have a critical role in the conversion yields of the reactions tested. Finally, the influence of different supports used for adsorption of the substrates was compared with respect to their efficiency in protecting the enzymatic activity.
Utilization of rice hull ash as a support material for immobilization of Candida cylindracea lipase
Authors: Tantrakulsiri Jitawan , Jeyashoke Narumon , Krisanangkura Kanit
Published: May 2007

Rice hull ash was heated in a muffle furnace at 700°C for 2 h and metallic oxides were leached with 10% sulfuric acid. The acid‐activated ash was then examined for immobilization of Candida cylindracea lipase. Immobilization was carried out by direct addition of the enzyme solution to the activated ash suspended in hexane. The immobilized lipase retained 30% of its hydrolytic activity, but thermal stability was greatly increased. Half‐lives of the immobilized enzyme at 50, 60, and 70°C were 45, 17, and 4 min, respectively. Optimal pH of the immobilized enzyme was 7.2. The apparent Km and Vmax for olive oil were 41 mM and 99.5 µmol/h‐mg solid, respectively.
A preliminary study on platelet aggregation in postmenopausal women consuming extra‐virgin olive oil and high‐oleic acid sunflower oil
Authors: Sánchez‐Muniz F. J. , Oubiña P. , Benedí J. , Ródenas S. , Cuesta C.
Published: May 2007

The purpose of the present study was to examine the effects of two monounsaturated fatty acid‐rich oils, extravirgin olive oil (EVOO) and high‐oleic sunflower oil (HOSO), on platelet aggregation in 14 postmenopausal women (aged 62.9 ± 1.8 yr) with high‐fat dietary habits. Both oils contained oleic acid as the major compound (≈76% of total fatty acids), but the content of palmitic and linoleic acids and many minor compounds was significantly different. These oils were used as the only culinary fats during two 28‐d periods, and represented ≈62% of the total lipid intake (≈46% of total energy consumption). Other dietary components were matched. The daily energy contribution of saturated, monounsaturated, and polyunsaturated fatty acids to the total energy consumption was 11.8, 28.5, and 2.8%, respectively, during the EVOO dietary period and 10.3, 27.8, and 4.6%, respectively, with HOSO. Aggregation in platelet‐rich plasma was measured after addition of ADP. Platelet aggregation (expressed as cm/5 min) was significantly lower after the EVOO diet than after HOSO (2.1 ± 1.1 and 3.0 ± 1.4, respectively; P<0.05). Although maximal aggregation time was 40.2% higher in HOSO than in EVOO, the difference was not significant. Independent of serum cholesterol level, platelet aggregation tended to be different on the EVOO diet when women were classified according to cholesterol levels: <220 mg/dL or ≥220 mg/dL. Results suggest that other compounds present in the oils aside from the fatty acids may play an important role in modulating platelet aggregation in these postmenopausal women.
Dietary arachidonic acid and hepatic desaturation of fatty acids in obese zucker rats
Authors: Blond Jean Paul , Durand Georges , Bézard Jean
Published: May 2007

The effect of low levels of dietary arachidonic acid (20:4n‐6) on Δ6 desaturation of linoleic acid (18:2n‐6) and α‐linolenic acid (18:3n‐3), and on Δ5 desaturation of dihomo‐γ‐linolenic acid (20:3n‐6) were studied in liver microsomes of obese Zucker rats, in comparison with their lean littermates. Fatty acid composition of serum total lipids and of phospholipids from liver microsomes and from total heart and kidney was determined to see whether modifications of desaturation rate, if any, were reflected in the tissue fatty acid profiles. Animals fed for 12 wk on a balanced diet, containing 20:4n‐6 and 18:2n‐6, were compared to those fed 18:2n‐6 only. The low amount of dietary 20:4n‐6 greatly inhibited Δ6 desaturation of 18:2n‐6 and Δ5 desaturation of 20:3n‐6, whereas Δ6 desaturation of 18:3n‐3 was slightly increased in obese rats. Inhibition of the biosynthesis of long‐chain n‐6 fatty acids by dietary arachidonic acid was only slightly reflected in the 20:4n‐6 content of liver microsome phospholipids. On the contrary, the enrichment of serum total lipids and heart and kidney phospholipids in this fatty acid was pronounced, more in obese than in lean animals. Our results show that, although the desaturation rate of the n‐6 fatty acids in liver microsomes was greatly decreased by the presence of arachidonic acid in the diet, the tissue phospholipid content in arachidonic acid was not depressed. The potentiality of synthesis of eicosanoids of the 2 family from this fatty acid is consequently not lower, especially in obese rats, in which certain tissues are deficient in arachidonic acid, in comparison with their lean littermates.
Changes of isoflavones during processing of soy protein isolates
Authors: Wang C. , Ma Q. , Pagadala S. , Sherrard M. S. , Krishnan P. G.
Published: May 2007

Soy protein isolate (SPI) is a widely used food ingredient and is made by extracting soy flour (SF) under slightly alkaline pH, followed by precipitation, washing, and drying. Soy foods and foods containing soy protein ingredients have great potential in the prevention of cardiovascular diseases and cancers. These health benefits have been attributed to isoflavones in soy protein ingredients. However, the current processing techniques were developed many years ago without this knowledge. The objective of this study was to investigate the mass balance of different isoflavones during manufacturing of SPI and to provide basic information to assist further development efforts leading to preservation of soy isoflavones in soy protein ingredients. The study revealed that only about 26% of the total isoflavones in SF remained in SPI. The percentages of total isoflavones lost during extraction, precipitation, and washing were 19, 14, and 22%, respectively. Washing was the step where most isoflavones were lost. The isoflavone profile of the SPI was different from that of SF. The former contained much more aglucones (genistein and daidzein), while the latter had almost none. The high content of aglucones in SPI was probably due to the hydrolysis of glycosides.
Supercritical CO2 extraction of rice bran
Authors: Kuk M. S. , Dowd M. K.
Published: May 2007

Extraction of rice bran lipids with supercritical carbon dioxide (SC‐CO2) was performed. To investigate the pressure effect on extraction yield, two isobaric conditions, 7000 and 9000 psi, were selected. A Soxhlet extraction with hexane (modified AOCS method Aa 4–38; 4 h at 69°C) was also conducted and used as the comparison basis. Rice bran with a moisture content of 6%, 90% passable through a sieve with 0.297 mm opening, was used for extraction. A maximum rice bran oil (RBO) yield of 20.5%, which represents 99+% lipid recovery, was obtained with hexane. RBO yield with SC‐CO2 ranged between 19.2 and 20.4%. RBO yield increased with temperature at isobaric conditions. At the 80°C isotherm, an increase in RBO yield was obtained with an increase in pressure. The pressure effect may be attributed to the increase in SC‐CO2 density, which is closely related to the value of the Hildebrand solubility parameter. RBO extracted with SC‐CO2 had a far superior color quality when compared with hexane‐extracted RBO. The level of sterols in SC‐CO2‐extracted RBO increased with pressure and temperature.
Lipids of Haliphthoros philippinensis: An oomycetous marine microbe
Authors: Kim H. , Gandhi S. R. , Moreau R. A. , Weete J. D.
Published: May 2007

Lipids of the marine oomycetous microbe Haliphthoros philippinensis were characterized by chromatographic and spectroscopic techniques. Total lipid content of this organism was relatively low and not very responsive to manipulation of the culture conditions. Neutral lipid comprised 21% of the total lipid and the polar lipids were mainly phosphatidylcholine (44%), phosphatidylethanolamine (15%), and a ceramide‐phosphorylethanolamine (19%). Palmitic (16:0) was the primary saturated fatty acid at 25% of the total fatty acids, and arachidonic acid (20:4n‐6, ARA) and eicosapentaenoic acid (20:5n‐3, EPA) were the major unsaturated fatty acids at 19 and 21%, respectively. Fucosterol was the principal sterol at 59% of the total sterols. The effects of several cultivation variables on growth and EPA production by this species were investigated. Among those tested, glucose and sodium glutamate were the most efficient carbon and nitrogen sources for growth, respectively. When the mycelium was cultivated for 6 d to produce biomass under optimal growth conditions, and then transferred to low temperature for an additional 13 d without glucose, the EPA content reached 31% of the total fatty acids and the yield was 203 mg/L. When the same experiment was performed with glucose supplementation during the low‐temperature phase, EPA composed 27% of total fatty acids and yield reached 316 mg/L, or a 285% increase over that from mycelium cultured for 6 d at 24°C, and 56% over that cultured at 16°C for 13 d. ARA production did not respond accordingly.
Similarities in the lipid class profiles of oils from Atlantic and Pacific dogfish livers
Authors: Kang S‐J. , Timmins M. C. A. , Ackman R. G.
Published: May 2007

Liver oils from Atlantic and Pacific dogfish (Squalus acanthias) have been compared for lipid classes, fatty acids of the total oil and of important lipid classes, and details of the alkyl chains in the 1‐O‐alkyl‐2,3‐diacylglycerol ethers (DAGE). In general there were few striking differences, confirming the view of biologists that these sharks are one species. The Pacific dogfish liver oil had a higher content (41.2%) of DAGE than the oil from Atlantic dogfish (18.2%). Both oils had all common and expected fatty acids in the proportions usual for marine oils, but they differed in the eicosenoic chains of the glycerol ethers (GE). The Pacific oil was unusual in having low but similar proportions of two alkyl chain isomers, 20:1n‐11 and 20:1n‐9. The Atlantic oil was very high in the 20:1n‐11 isomer, which is usually lower than 20:1n‐9 in the fatty acids of most regional marine oils. Unexpectedly, the DAGE of both oils had further unusual 20:1 isomer proportion in the GE chain, with 20:1n‐7 >20:1n‐9. Minor oddities in the fatty acids may reflect different basic food sources.
Volatile compounds produced during deodorization of soybean oil and their flavor significance
Authors: Kao Jian‐Wen , Hammond Earl G. , White Pamela J.
Published: May 2007

Freshly deodorized soybean oil has a characteristic nutty flavor but often yields no detectable headspace volatiles. The cause of this flavor was investigated by deodorizing soybean oil in an apparatus with a double cold trap that allowed the volatile compounds formed from the initial decomposition of hydroperoxides to be collected separately from those produced during the normal deodorization process. The chief volatile components from the normal deodorization process were hydrocarbons, which contributed little to no odor to the oil. The compounds with the greatest odor were carbonyls, especially heptanal and cis‐4‐heptenal. Although these components should accumulate at some steady‐state concentration in an oil during its deodorization, none seemed to account for the flavor of the deodorized oil. By using a particle detector, it was shown that small particles could be generated in the human mouth that could provide a mechanism to bring oil with nonvolatile flavor components into contact with the olfactory organ. Attempts to separate possible nonvolatile flavors in deodorized oil from triacylglycerides by chromatography on alumina or reaction with 2,4‐dinitrophenylhydrazine were unsuccessful. Possibly, the flavor is caused by the glycerol esters themselves.
Correlating viscosity with temperature and other properties
Authors: Fisher Charles H.
Published: May 2007

Simple viscosity equations based on linearities [1/ηe (or φe) vs. T; T/ηe vs. T and φe vs. P; (η, viscosity; φ, fluidity; T, temperature; and P, any property or property function linear with T, such as, density, refractivity, and surface tension)] are given for glycerol, triglycerides, glyceride oils, n‐fatty acids, esters, an alcohol, and an amine.
A comparison of physical and chemical properties of milk fat fractions obtained by two processing technologies
Authors: Bhaskar A. R. , Rizvi S. S. H. , Bertoli C. , Fay L. B. , Hug B.
Published: May 2007

Milk fat fractions from supercritical carbon dioxide (SC‐CO2) extraction were compared with commercial melt crystallization (MC) fractions for their physical and chemical properties. The fractions were analyzed for fatty acids, triacylglycerols, cholesterol, total carotenoid content, and volatile compounds. The fractions were also evaluated for solid fat content (SFC) by pulsed nuclear magnetic resonance and thermal profiles by differential scanning calorimeter (DSC). The distribution of fatty acids and triacylglycerols in the fractions depended on the fractionation technique used. SC‐CO2 separated fractions based on molecular weight rather than on melting point, which is the driving force for the MC process. The differences among the fractions were quantified from their SFC and DSC curves. Triacylglycerol profiles by high‐performance liquid chromatography showed that the SC‐CO2 fractions were distinctly different from each other and from MC fractions. The SC‐CO2 solid fraction (super stearin) was the most unique. It had a high concentration of long‐chain, unsaturated fatty acid‐containing triacylglycerols in a narrow range of high molecular weight, indicating a homogeneity of this fraction that has not been attainable by other techniques. It was also enriched in β‐carotene and was devoid of volatile compounds. As compared to liquid MC fractions, the liquid SC‐CO2 fraction had a high concentration of low‐melting triacylglycerols and was enriched in volatile compounds. With SC‐CO2, it is thus possible to simultaneously fractionate and produce a flavor‐rich concentrate at no extra processing cost.