bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term behavior of oil‐based varnishes and paints. Fate of hydroperoxides in drying oils
Authors: Mallégol Jacky , Gardette Jean‐Luc , Lemaire Jacques
Published: November 2006

The thermal stability of linseed oil and poppyseed oil hydroperoxides in a temperature range from ambient to 120°C has been investigated on the basis of iodometric titration. The peroxide value (PV) vs. oxidation time curves show similar developments at the six temperatures chosen for the experiments. These curves are characterized by a fast increase in the PV up to a maximal value, followed by a decrease in the PV at a lower rate. The maximal PV is higher when the curing temperature is lowered. This result indicates thermal decomposition of the hydroperoxides. The peroxy crosslink concentration in the dried oil film varies similarly to the hydroperoxide concentration. This indicates that, for dried films, the network is almost totally constituted of ether and C‐C crosslinks. A comparison of the rates of peroxide decomposition under thermolytic and thermooxidative conditions has evidenced that the only homolytic scission of the O‐O bonds cannot justify the decreased of the PV in thermooxidation. Another mechanism accounting for hydroperoxide decomposition, based on an induced decomposition of the hydroperoxides, has been proposed. These results have permitted completing the description of the curing mechanisms of drying oils.
Preparation of rapeseed oil esters of lower aliphatic alcohols
Authors: Nimcevic Dragan , Puntigam Rupert , Wörgetter Manfred , Gapes J. Richard
Published: November 2006

Rapeseed oil esters with lower aliphatic alcohols (C1−C4) were prepared in simple batch mode using an alkali (KOH) or acid (H2SO4) catalyst. The transesterification reaction conditions were optimized in order to obtain high yields of esters of the quality defined by standards for biodiesel fuels and for a short reaction time. Under these conditions it was possible to prepare only the methyl and ethyl esters catalyzed by KOH. Propyl and butyl esters were obtained only under acid catalysis conditions. The reaction catalyzed by H2SO4 was successfully accelerated using slightly higher catalyst concentrations at the boiling points of the alcohols used. The branched‐chain alcohols reacted more slowly than their linear homologs, while t‐butanol did not react at all. It was also possible to transesterify rapeseed oil using a mixture of alcohols characteristic of the end products of some fermentation processes (e.g., the acetone‐butanol fermentation). A simple calculation was made which showed that, because of the higher price of longer‐chain alcohols and because of the more intensive energy input during production the esters of these alcohols, they are economically unfavorable as biodiesel fuels when compared with the methyl ester.
Simultaneous determination of lodine value and trans content of fats and oils by single‐bounce horizontal attenuated total reflectance fourier transform infrared spectroscopy
Authors: Sedman Jacqueline , van de Voort F. R. , Ismail Ashraf A.
Published: November 2006

A method for the simultaneous determination of iodine value (IV) and trans content from the Fourier transform infrared (FTIR) spectra of neat fats and oils recorded with the use of a heated single‐bounce horizontal attenuated total reflectance (SB‐HATR) sampling accessory was developed. Partial least squares (PLS) regression was employed for the development of the calibration models, and a set of nine pure triacylglycerols served as the calibration standards. Regression of the FTIR/PLS‐predicted IV and trans contents for ten partially hydrogenated oil samples against reference values obtained by gas chromatography yielded slopes close to unity and SD of <1. Good agreement (SD<0.35) also was obtained between the trans predictions from the PLS calibration model and trans determinations performed by the recently adopted AOCS FTIR/SBHART method for the determination of isolated trans isomers in fats and oils.
Rapid determination of total Trans fat content by attenuated total reflection infrared spectroscopy: An international collaborative study
Authors: Adam Michael , Mossoba Magdi M. , Lee Theresa
Published: November 2006

Interest in trans fat labeling has prompted efforts to develop new, more efficient methods for rapidly and accurately determining trans fat content in foods. The lower limit of quantitation, 5% trans fat (as percent of total fat), of transmission infrared official methods, such as AOAC 994.14 and 965.34, for total isolated trans fatty acids is too high to be generally useful for the determination of low levels of trans fats in foods. A novel and rapid (5 min) attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopic procedure was recently developed and applied to food products. This procedure was voted official method AOCS Cd 14d‐99 by the American Oil Chemists' Society in 1999 after testing in a 12‐laboratory international collaborative study. The results of this study are described in this paper. Analytical ATR‐FTIR results exhibited high accuracy in the range investigated, 1–40% trans; results tended to have <2% high bias relative to the gravimetrically determined values. The precision of this internal reflection method was found to be superior to those of transmission infrared official methods. It is recommended that the applicability of the ATR‐FTIR method be limited to trans levels of >1% (as percent of total fat).
Five‐factor response surface optimization of the enzymatic synthesis of citronellyl butyrate by lipase IM77 from Mucor miehei
Authors: Shieh Chwen‐Jen , Lou Ya‐Hui
Published: November 2006

Response surface methodology (RSM) and a five‐level‐five‐factor central composite rotatable design (CCRD) were used to evaluate the effects of synthetic variables, such as reaction time (3 to 27 h), temperature (25 to 65 °C), enzyme amount (10 to 50%), substrate molar ratio of citronellol to butyric acid (1∶1 to 1∶3), and added water amount (0 to 20%) on molar percent yield of citronellyl butyrate by direct esterification, using lipase IM77 from Mucor miehei. Reaction time and temperature were the most important variables. Substrate molar ratio had no effect on percent molar conversion. Based on contour plots, optimal synthetic conditions were these: reaction time 24 h, temperature 60°C, enzyme amount 20%, substrate molar ratio 1∶1.5, and added water 0%. The predicted molar conversion value was 100%. An actual experimental value of 98% molar conversion was obtained.
Electron spin resonance spectroscopy for determination of the oxidative stability of food lipids
Authors: Thomsen Marianne K. , Kristensen Dorthe , Skibsted Leif H.
Published: November 2006

Evaluation of the oxidative stability of food lipids based on the tendency of formation of radicals is shown to be possible using electron spin resonance (ESR) spectroscopy and the spin‐trapping technique. Induction time can be determined for mildly accelerated conditions (50°C for lipid fraction from mayonnaise enriched with fish oil), and the length of the induction time decreases during storage and γ‐tocopherol depletion. The protection by ethylenediaminetetraacetic acid against initiation of lipid oxidation is also detected in the new assay. For more oxidatively stable lipids (butter, rapeseed oil, dairy spread) the mildly accelerated conditions can be used in the assay, provided that difference in signal height for fixed times replaces determination of induction time. ESR spin trapping provides a sensitive method for evaluating the oxidative stability of food lipids. Detection of radicals in the lipid as an early event in oxidation allows mild conditions to be used, and future experiments should also include sensory evaluation in relation to determination of practical shelf life.
Quantitative analysis of partial acylglycerols and free fatty acids in palm oil by 13C nuclear magnetic resonance spectroscopy
Authors: Ng Soon
Published: November 2006

The chemical shifts, spin‐lattice relaxation times (T1), and one‐bond C−H coupling constants of the glycerol carbons of mono‐, di‐, and triacylglycerols in CDCI3 solution are presented and discussed. The glycerol carbons have low T1 values (<1.0 s) and full nuclear Overhauser effect and also exhibit broader linewidths than the aliphatic carbons, suggesting that the glycerol carbons are at or near the T1 minimum for the dipole‐dipole relaxation mechanism. Therefore, for quantitative measurement of the composition of partial acylglycerols (relative to the triacylglycerols) in palm oil, the nuclear magnetic resonance (NMR) spectrum of the β‐carbons, which lie exclusively in the region δ68.3–72.1 ppm, should preferably be acquired at medium or low magnetic fields and at an elevated temperature in order to ensure that the condition for extremely narrow spectral lines is satisfied. The chemical shifts and spinlattice relaxation times of the aliphatic C‐2 and C‐3 carbons and of the carbonyl carbons (C‐1) of acyl groups present in palm oil are also presented and discussed. The presence of free fatty acid in the palm oil is easily detected and quantified in the spectrum of the aliphatic carbons. The presence of partial acylglycerols in palm oil can also be detected and/or quantified in the NMR spectra of the C‐2 and the carbonyl carbons. The quantitative analysis of the glycerol carbons of a known mixture of acylglycerols obtained by using this method is presented.
Effects of minor lipids on crystallization of milk fat‐cocoa butter blends and bloom formation in chocolate
Authors: Tietz R. A. , Hartel R. W.
Published: November 2006

Minor lipids, such as diacylglycerols, monoacylglycerols, cholesterol, and phospholipids play a key role in crystallization of fats. In this study, the effects of minor lipid components on crystallization of blends of cocoa butter (CB) with 10% milk fat or milk‐fat fractions, and on bloom formation of chocolate were investigated. Both removing the minor lipids from milk fat and doubling the level of minor lipids from milk fat resulted in longer nucleation onset time, slower crystallization rate, and rapid bloom development in chocolate. Removal of minor lipids resulted in the formation of irregular primary and secondary crystals with inclusions of liquid fat, whereas the crystals were spherical and uniform in shape in the presence of minor lipids. Minor lipids from milk fat, even at the low concentrations typically found in nature, affected the crystallization of milk fat‐CB blends, impacted the chocolate microstructure, and affected bloom development in chocolate.
Enzyme hydrolysis of babassu oil in a membrane bioreactor
Authors: bio Mer on F , Sant Anna Geraldo Lippel , Nobrega Ronaldo
Published: November 2006

This work deals with the enzymatic hydrolysis of babassu oil by immobilized lipase in a membrane bioreactor using unmixed aqueous and lipid streams. The experimental work was carried out in a flat plate membrane module with two different membranes: hydrophobic (nylon) and hydrophilic [mixed cellulose esters (MCE)], with different nominal pore sizes ranging from 0.10 to 0.65 μm. Candida cylindracea lipase was adsorbed on the membrane surface area, and the reactor was operated in batch mode. The initial enzymatic rate increased from 80 to 150 μmol H+/min when the organic phase velocity increased from 1.0×10−3 to 3.0×10−3 m/s, indicating that mass transfer in that phase was the process‐limiting step. Calcium ions had a marked effect on immobilized lipase activity, increasing around twofold the lipolytic activity. Long‐term experimental runs showed that the immobilized lipase remained stable for at least 8 d. The values for immobilized protein and maximal productivities observed for 0.45 μm membranes were: 1.01 g/m2 and 193 μmol H+/m2·s for MCE membrane and 0.78 g/m2 and 220 μmol H+/m2·s for nylon membrane. The productivities obtained are among the highest values reported in the technical literature.
Oil‐water interfacial activation of lipase for interesterification of triglyceride and fatty acid
Authors: Maruyama Tatsuo , Nakajima Mitsutoshi , Uchikawa Sosaku , Nabetani Hiroshi , Furusaki Shintaro , Seki Minoru
Published: November 2006

Lipase usually has little interesterification activity in organic solvents, probably owing to the absence of an oil‐water interface. Lipases were processed in a two‐phase hydrocarbon‐water system that had an oil‐water interface. Crude lipase (from Rhizopus japonicus) in a buffer and a small volume of aliphatic hydrocarbon as an oil phase were mixed and then lyophilized to remove the aqueous and oil phases. The interfacially processed lipase has a remarkable interesterification activity in n‐hexane compared to crude native lipases. We postulate that this activation is caused by the oil‐water interface, i.e., the interface between hydrocarbon and water makes the lipase lid open and enables the lipase to work effectively in n‐hexane. Several different hydrocarbons were investigated as an oil phase, and n‐tetradecane was found to be the best for interesterification. Activated lipase was successfully inactivated in a water suspension without an oil‐water interface, and the inactivated lipase could be reactivated. We demonstrated that the oil (hydrocarbon)‐water interface induced reversible activation to lipase for interesterification.
Chemoenzymatic synthesis of structured triacylglycerols containing eicosapentaenoic and docosahexaenoic acids
Authors: Haraldsson Gudmundur G. , Halldorsson Arnar , Kuls Elin
Published: November 2006

There are indications in the recent literature that the location of polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in triacylglycerols (TAG) may influence their oxidative stability. To address that question, two types of structured lipids were designed and synthesized: firstly, a TAG molecule possessing pure EPA or DHA at the mid‐position with stearic acid at the outer positions; and secondly, a TAG molecule possessing pure EPA or DHA located at one of the outer positions with stearic acid at the mid‐position and the remaining end position. The former adduct was synthesized in two steps by a chemoenzymatic approach. In the first step 1,3‐distearolyglycerol was afforded in good yield (74%) by esterifying glycerol with two equivalents of stearic acid in ether in the presence of silica gel using LipozymeTM as a biocatalyst. This was followed by a subsequent chemical esterification with pure EPA or DHA using 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide as a coupling agent in the presence of 4‐dimethylaminopyridine in dichloromethane in excellent yields (94 and 91, respectively). The latter adduct was synthesized in two enzymatic steps. In the first step tristearoylglycerol was prepared in very high yield (88%) by esterifying glycerol with a stoichiometric amount of stearic acid under vacuum at 70–75°C using an immobilized Candida antarctica lipase without a solvent. That adduct was subsequently treated in an acidolysis reaction with two equivalents of EPA or DHA without solvent at 70–75°C or in toluene at 40°C in the presence of Lipozyme to afford the desired product in moderate yields (44 and 29%, respectively).
Physicochemical properties of pronase‐treated rice glutelin
Authors: Anderson A. , Hettiarachchy N. , Ju Z. Y.
Published: November 2006

Rice glutelin protein was extracted from defatted medium‐grain rice by alkali extraction followed by acid precipitation. Extracted glutelin was hydrolyzed with Pronase E, a bacterial protease, and the functional properties of hydrolysates were evaluated. Nitrogen solubility of pronase‐treated glutelin protein increased from pH 2 to pH 12. Similarly, foaming and emulsion properties of hydrolyzed protein also showed improved characteristics. The emulsion activity, expressed as the turbidity of diluted emulsions, was significantly greater (P≤0.05) for hydrolyzed samples. However, turbidity for all samples decreased with increased homogenization time, indicating a decrease in the volume of dispersed oil. There were significant changes in apparent viscosity as a function of shear rate, with viscosity decreasing with increasing shear rate. The viscosity of dispersions of all hydrolyzed samples was significantly lower than that of the native sample at all shear rates tested. Enzymatic hydrolysis of rice endosperm storage glutelin proteins appeared to improve the functional characteristics of the hydrolyzed proteins.
Refining high‐free fatty acid wheat germ oil
Authors: Wang Tong , Johnson Lawrence A.
Published: November 2006

Wheat germ oil was refined using conventional degumming, neutralization, bleaching, and continuous tray deodorization, and the effects of processing conditions on oil quality were determined. The crude wheat germ oil contained 1,428 ppm phosphorus, 15.7% free fatty acid (FFA), and 2,682 ppm total tocopherol, and had a peroxide value (PV) of 20 meq/kg. Degumming did not appreciably reduce the phosphorus content, whereas neutralization was effective in removing phospholipid. Total tocopherol content did not significantly change during degumming, neutralization, and bleaching. A factorial experimental design of three deodorization tempeatures and three residence times (oil flow rates) was used to determine quality changes during deodorization. High temperatures and long residence times in deodorization produced oils with less FFA, PV, and red color. Deodorization at temperatures up to 250°C for up to 9 min did not significantly reduce tocopherol content, but, at 290°C for 30‐min residence time, the tocopherol content was significantly reduced. Good‐quality wheat germ oil was produced after modifying standard oil refining procedures.
Free radical scavenging capacity as related to antioxidant activity and ginsenoside composition of Asian and North American ginseng extracts
Authors: Hu Chun , Kitts David D.
Published: November 2006

Different Panax species derived from Asia (Panax ginseng C.A. Meyer) and North America (Panax quinquefolium L.) were extracted by methanol and evaluated for relative ginsenoside composition and antioxidant activities. Ginseng root contained a greater proportion of total ginsenoside compared to ginseng hair analyzed by high‐performance liquid chromatography. North American ginseng root was characterized with undetectable ginsenoside Rf and greater Rb1/Rb2 than Asian ginseng root. Panax quinquefolium exhibited a relatively higher (P<0.05) affinity to scavenge free radical than panax ginseng using the 2,2‐azobis (3‐ethylbenzothine‐6‐thine‐6‐surfonic acid) radical model. In a bilayer lamella suspension oxidation model induced by peroxyl radicals, ginseng samples exhibited notable antioxidant activity. Specifically, however, the P. quinquefolium extracts delayed lipid peroxidation longer (P<0.05) than the P. ginseng extracts. Ginseng extracts from both Panax species protected human low‐density lipoprotein against cupric ion‐mediated oxidation. Similar protection was observed against peroxyl radical‐induced supercoiled DNA breakage. A pure ginsenoside standard (e.g., Rb1) produced similar results. The antioxidant activities of different ginseng species and specific plant parts include free radical scavenging and may be related to ginsenoside Rb1/Rb2 content.
Adsorption equilibria of fatty acids between methanol/water and reversed‐phase chromatographic adsorbents
Authors: Ib ez Gonz lez M. J. , Medina A. Robles , Esteban Cerd n L. , Camacho P ez B. , Gim nez Gim nez A. , Grima E. Molina
Published: November 2006

The adsorption equilibria are discussed for fatty acids 16∶1n−7, 16∶2n−4, and 20∶5n−3 (eicosapentaenoic acid, EPA). These fatty acids are major components of a polyunsaturated fatty acid concentrate from the microalga Phaeodactylum tricornutum. The solvents used were methanol/water (1% acetic acid) mixtures of different compositions, and the adsorbents used were chromatographic reversed‐phases octylsilyl C8, octadecylsilyl C18, and dodecylsilyl C22 of different particle and pore sizes. The kinetic studies showed that equilibrium was attained instantaneously, suggesting an absence of mass transfer limitations. The equilibrium data were fitted by the Freundlich isotherm. The separation efficiency of EPA from 16∶1n−7 and 16∶2n−4 in all the adsorbent‐solvent systems was compared in terms of the separation factors αEPA/16:2n‐4=KEPA/K16:2n‐4 and α16:1n‐7/EPA=K16:1n‐7/KEPA, where Ki is the fatty acid distribution ratio between the stationary and the liquid phases. The EPA separation from 16∶1n−7 and 16∶2n−4 by liquid chromatography could be predicted using the Craig model for the various solvent‐adsorbent combinations. The best adsorbents for purifying EPA were: C18, PEP, 8 μm, 100 Å, and C22, 10 μm, 100 Å, and the best solvent was methanol/water (1% acetic acid) 75∶25, w/w.
Metabolic mechanisms associated with alleles governing the 16:0 concentration of soybean oil
Authors: Wilson R. F. , Marquardt T. C. , Novitzky W. P. , Burton J. W. , Wilcox J. R. , Kinney A. J. , Dewey R. E.
Published: November 2006

Soybean [Glycine max (L.) Merr.] oil typically contains ca. 11% palmitic acid, but germplasm has been developed with less than 4% to about 35% 16∶0, A number of recessive alleles associated with these phenotypes have been described thattrepresent different mutations at Fap loci, however, the gene products (enzymes) produced by these alleles are unknown. This work attempts to define the metabolic activities that are regulated by the fap1, fap2, and fapnc alleles in soybean. Observation of de novo synthesis and metabolic turnover of fatty acids esterified to phospholipids in cotyledons during the period of peak oil accumulation revealed genotypic differences in the supply of 16∶0‐CoA from plastids. These metabolic studies narrowed the identification of fap1, fap2, and fapnc alleles to the genes that encode or regulate the 3‐keto‐acyl‐ACP synthetase II (where ACP is acyl carrier protein), 16∶0‐ACP thioesterase, 18∶0‐ACP desaturase, or 18∶1‐ACP thioesterase enzymes. Kinetic analyses suggested that the fap2 mutation results in a decreased 3‐keto‐acyl‐ACP synthetase II activity. Deficiencies in 16∶0‐ACP thioesterase activity represented the most likely explanation of fap1 and fapnc gene function. This hypothesis was strongly supported by Northern blot assays that revealed a significant reduction in the accumulation of transcripts corresponding to the 16∶0‐ACP thioesterase in germplasm homozygous for the fapnc allele.
A kinetic model for the enzyme‐catalyzed self‐epoxidation of oleic acid
Authors: Yadav G. D. , Manjula Devi K.
Published: November 2006

This paper reports a kinetic model for the selfepoxidation of oleic acid with toluene as solvent and Novozym 435 (a commercially available preparation of immobilized Candida antarctica lipase) as catalyst at 30°C. The effects of various parameters on the conversion and rates of reaction were studied. Both the initial rate and the progress curve data were used to fit an ordered bi‐bi model. At low temperatures, the rate of epoxidation was faster than the rate of deactivation of the enzyme by hydrogen peroxide.
Nitrogen bubble refining of sunflower oil in shallow pools
Authors: Tsiadi A. V. , Stavrides E. , Handa‐Corrigan A.
Published: November 2006

High‐temperature steam deodorization of sunflower oil results in the formation of unwanted by‐products, such as trans isomers and polymers, and partial destruction of vitamins. There is an urgent need to develop a process that replaces steam with an inert gas such as nitrogen. The use of nitrogen bubble sparging at low temperatures has recently been reported as a technique to strip volatiles from edible oils. In this study, a hypothesis was proposed that nitrogen bubbles sparged at temperatures of 25 to 150°C are able to remove odoriferous, surface‐active, or volatile contaminants from shallow pools of sunflower oil. Analysis of the composition of sunflower oil that had been sparged at 3 mbar pressure showed that both the odor and peroxide content of the oil were considerably reduced to values that are commercially acceptable. Odor improvement occurred at temperatures between 100 and 150°C, while the peroxide content reduction was achieved at a temperature of 150°C. There were no significant improvements in the free fatty acid concentration or color.
Interesterification of tallow and sunflower oil
Authors: Rodríguez Alicia , Castro Eduardo , Salinas María C. , López Reinaldo , Miranda Misael
Published: November 2006

The objective of this study was to manufacture a shortening using chemical interesterification (IT) of tallow‐sunflower oil blends to replace fish oil in the present formulation, which is now in short supply in Chile. The significant variables of the IT process were obtained by 24−1 fractional factorial design. The proportion of tallow (T) in the blend, catalyst concentration, and reaction temperature had a significant effect on the melting point (mp) (P≤0.05). IT of tallow and sunflower oil blends (90∶10 and 70∶30) diminished the mp, dropping point, and refractive index compared to tallow. However, a noninteresterified 90∶10 blend mp was not significantly different from tallow. IT produced a solid fat content (SFC) profile of IT90∶10 blend that was appropriate for use in shortenings for the baking industry. Blending and IT of the 90∶10 blend increased the melting profile of the tallow and the melting range from −40 to 60°C while the endotherms of the middle‐melting triacylglycerols (TAG) decreased. The IT90∶10 blend hardnesswas 70% lower than tallow hardness, and the crystal network was composed of large spherulites in a network. IT resulted in an appropriate method to improve physical properties of tallow, whereas blending did not significantly modify it. The interesterification changed the SFC profile of IT90∶10, giving a more appropriate shortening for use in the baking industry.
Fractionation of urea‐pretreated squid visceral oil ethyl esters
Authors: Hwang Lucy Sun , Liang Jer‐Hour
Published: November 2006

Ethyl esters of squid (Illex argentinus) visceral oil contained 11.8% eicosapentaenoic acid (EPA) and 14.9% docosahexaenoic acid (DHA). The esters were treated with urea to increase the contents of EPA and DHA. The non‐urea complexing ethyl esters of squid visceral oil contained 28.2% EPA and 35.6% DHA. This mixture was fractionated by molecular distillation to further increase the EPA or DHA content. The fraction collected in the 110°C distillate had an EPA content of 39.0% with 0.26 g/100 g of cholesterol, while the 130°C distillate contained 65.6% DHA and 0.42 g/100 g of cholesterol. Ethyl esters prepared from visceral oil of squid Ommastrephes bartrami had 4.5% EPA and 12.7% DHA. After urea pretreatment, the EPA and DHA contents were raised to 10.1 and 30.0%, respectively. When this mixture was further fractionated by molecular distillation, 16.9% EPA with 0.35 g/100 g cholesterol was found in the 110°C distillate and 52.6% DHA with 0.70 g/100 g cholesterol was found in the 130°C distillate. Cholesterol in the squid visceral oil ethyl esters was concentrated in the final residue of molecular distillation when the polyunsaturated ethyl esters were enriched by the urea complexation method prior to molecular distillation. For example, the cholesterol content in the ethyl esters from O. bartrami squid visceral oil was 2.28 g/100 g originally. It was enriched to 64.15 g/100 g in the final residue from the molecular distillation.
Incorporation of bromo‐octadecane into long‐chain ester monolayers at the air/water interface
Authors: Baskar Geetha , Shanmugharaj A. M. , Venkatesh S. , Mandal A. B.
Published: November 2006

Surface compatibility of 2‐methoxy ethyl stearate and oleate esters with 1‐bromo‐octadecane (RBr) has been investigated at the air/water interface with a Langmuir film balance. The methoxy ethyl head group in the esters promotes flat conformation at the air/water interface as observed from its higher surface area (stearate, 22.41 Å2/molecule; oleate, 57.20 Å2/molecule) in comparison to the corresponding acids. The stearate ester forms a homogeneous mixed monolayer with maximal incorporation of 0.5 mole fraction of RBr. This is indicated by the retention of liquid condensed and solid condensed phases of stearate ester, and the positive deviation of the mean molecular area of the mixed film from the calculated additive areas. When the mole fraction of RBr (x2) exceeds 0.5, the onset of formation of heterogeneous mixed film is indicated by the appearance of initial and final collapse pressures. On the contrary, oleate ester shows the least compatibility with RBr, which is indicated by the progressive decrease in mean molecular area with x2. The more liquid expanded‐phase structure of oleate ester probably does not promote compatibility with RBr at the air/water interface.
Synthesis of estolides from oleic and saturated fatty acids
Authors: Cermak Steven C. , Isbell Terry A.
Published: November 2006

Oleic acid and various saturated fatty acids, butyric through stearic, were treated with 0.4 equivalents of perchloric acid at either 45 or 55°C to produce complex estolides. Yields varied between 45 and 65% after Kugelrohr distillation. The estolide number (EN), i.e., the average number of fatty acid units added to a base fatty acid, varied as a function of temperature and saturated fatty acid. The shorter‐chain saturated fatty acids, i.e., butyric and hexanoic, provided material with higher degrees of oligomerization (EN=3.31) than stearic acid (EN=1.36). The individual, saturated fatty acid estolides each have very different characteristics, such as color and type of by‐products. The higher‐temperature reactions occurred at faster rates at the expense of yield, and lactones were the predominant side products. At 55°C, lactone yields increased, but the δ‐γ‐lactone ratio decreased; this led to lower estolide yields. The opposite trend was observed for the 45°C reaction. The saturate‐capped, oleic estolides were then esterified with 2‐ethylhexyl alcohol, and the chemical composition of these new estolides remained consistent throughout the course of the reaction.
Long storage stability of biodiesel made from rapeseed and used frying oil
Authors: Mittelbach M. , Gangl S.
Published: November 2006

The degree of physical and chemical deterioration of biodiesel produced from rapeseed and used frying oil was studied under different storage conditions. These produced drastic effects when the fuel was exposed to daylight and air. However, there were no significant differences between undistilled biodiesel made from fresh rapeseed oil and used frying oil. The viscosity and neutralization numbers rose during storage owing to the formation of dimers and polymers and to hydrolytic cleavage of methyl esters into fatty acids. However, even for samples studied under different storage conditions for over 150 d the specified limits for viscosity and neutralization numbers had not been reached. In European biodiesel specifications there will be a mandatory limit for oxidative stability, because it may be a crucial parameter for injection pump performance. The value for the induction period of the distilled product was very low. The induction period values for the undistilled samples decreased very rapidly during storage, especially with exposure to light and air.
A possible way to predict the genetic relatedness of selected almond cultivars
Authors: Grane‐Teruel N. , Prats‐Moya M. S. , Berenguer‐Navarro V. , Martin‐Carratala M. L.
Published: November 2006

Some multivariate statistical techniques were applied to the fatty acid composition of almond seed for a set of 107 samples of cultivars grown in different environmental conditions. These techniques reveal a close similarity in fatty acid composition among a cultivar and its ancestors as in the case of Ferragnes and Masbovera. Interestingly, the Guara cultivar seems to be very similar to the Tuono cultivar. Another finding suggests that the typical Spanish cultivars Desmayo Largueta and Marcona have a similar fatty acid profile to the American cultivar Non Pareil. Independent of environmental conditions, this shows a possible common parentage in the pedigree of these cultivars.
Application of standard addition to eliminate conjugated linoleic acid and other interferences in the determination of total Trans fatty acids in selected food products by infrared spectroscopy
Authors: Mossoba M. M. , Kramer J. K. G. , Fritsche J. , Yurawecz M. P. , Eulitz K. D. , Ku Y. , Rader J. I.
Published: November 2006

A novel and rapid (5 min) attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) spectroscopic method AOCS Cd 14d‐99 for the determination of total isolated trans fatty afids, which absorb at 966 cm‐, was recently developed, collaboratively studied, and applied to food products containing 1–50% rans fat (as percentage of total fat). Attempts to apply the ATR‐FTIR method to biological matrices of low trans fat and/or low total fat content, and to dairy and other products were not satisfactory due to interfering IR absorptions in the trans region. One group of interfering compounds with absorption bands near 985 and 948 cm−1 was the cis/trans positional isomes of conjugated linoleic acid (CLA) found in dairy and meat products from ruminants at levels of <1% (as percentage of total fat). In the present study, we modified the ATR‐FTIR method to overcome matrix interferences. This modification, which consisted of applying the standard addition technique to the ATR‐FTIR determination, was also applied to several food products, namely, dairy products, infant formula and salad oil dressing, which successfully eliminated interfering absorbances that impacted on accuracy. The presence of <1% CLA in two butter and two cheese products containing 6.8, 7.5, 8.5, and 10.4% trans fatty acids (as a percentage of total fat) would have led to errors of −11.6, 10.4, 17.6 and 34.6%, respectively, in trans fat measurements had the standard addition technique not been used. The applicability of ATR‐FTIR to the quantitation of food products is discussed.
Enzymatic conversion of waste edible oil to biodiesel fuel in a fixed‐bed bioreactor
Authors: Watanabe Yomi , Shimada Yuji , Sugihara Akio , Tominaga Yoshio
Published: November 2006

The conversion of waste edible oil to biodiesel fuel in a fixed‐bed bioreactor was investigated. Three‐step methanolysis of waste oil was conducted using three columns packed with 3 g of immobilized Candida antarctica lipase. A mixture of waste oil and 1/3 molar equivalent of methanol against total fatty acids in the oil was used as substrate for the first‐step reaction, and mixtures of the first‐ and second‐step eluates and 1/3 molar equivalent of methanol were used for the second‐ and third‐step reactions, respectively. Ninety percent of waste oil was converted to the corresponding methyl esters (ME) by feeding substrate mixtures into the first, second, and third reactors at flow rates of 6, 6 and 4 mL/h, respectively. We also attempted one‐step methanolysis of waste oil. When a mixture of waste oil and 90% ME‐containing eluate (1∶3, wt/wt) and an equimolar amount of methanol against total fatty acids in the waste oil was fed into a reactor packed with 3 g of immobilized C. antarctica lipase at a flow rate of 4 mL/h, the ME content in the eluate reached 90%. The immobilized biocatalyst could be used for 100 d in the two reaction systems without significant decrease in its activity. Waste oil contained 1980 ppm water and 2.5% free fatty acids, but these contaminants had little influence on enzymatic production of biodiesel fuel.
Kinetics of the formation of symmetrical wax esters from the corresponding alcohols with the use of hydrobromic acid and hydrogen peroxide
Authors: Kulkarni Mangesh G. , Sawant Sudhirprakash B.
Published: November 2006

The primary aliphatic alcohols n‐octanol, n‐decanol, and n‐dodecanol have been converted to their corresponding symmetrical esters by using HBr and H2O2 in the absence of a solvent. The reaction was carried out at 30, 40, and 50°C and at mole ratios of alcohol to HBr of 1∶0.1, 1∶0.2, 1∶0.3, and 1∶0.5. The rate of the reaction was found to increase with increase in the reaction temperature and concentration of HBr. The maximal conversion of n‐octanol was 72% at 40°C and a mole ratio of n‐octanol to HBr of 1∶0.5. The kinetics of the reaction have been established, and the reaction was found to be first‐order with respect to alcohol and bromine concentration in the organic phase, and second‐order with respect to both. The second‐order rate constants for n‐octanol, n‐decanol, and n‐dodecanol are 27.08, 32.58, and 37.42 mL mol−1 min−1, respectively, at 40°C. The activation energy for the esterification reaction of n‐octanol was found to be 16.32 kcal mol−1.
Detection of lard mixed with body fats of chicken, lamb, and cow by fourier transform infrared spectroscopy
Authors: Che Man Y. B. , Mirghani M. E. S.
Published: November 2006

Fourier transform infrared (FTIR) spectroscopy provides a simple and rapid means of detecting lard blended with chicken, lamb, and cow body fats. The spectral bands associated with chicken, lamb, and cow body fats and their lard blends were recorded, interpreted, and identified. Qualitative differences between the spectra are proposed as a basis for differentiating between the pure animal fats and their blends. A semiquantitative approach is proposed to measure the percent of lard in blends with lamb body fat (LBF) on the basis of the frequency shift of the band in the region 3009–3000 cm−1, using the equation y=0.1616x+3002.10. The coefficient of determination (R2) was 0.9457 with a standard error (SE) of 1.23. The percentage of lard in lard/LBF blends was also correlated to the absorbance at 1417.89 and 966.39 cm−1 by the equations y=0.0061x+0.1404 (R2=0.9388, SE=0.018) and y=0.004x+0.1117 (R2=0.9715, SE=0.009), respectively. For the qualitative determination of lard blended with chicken body fat (CF), the FTIR spectral bands in the frequency ranges of 3008–3000, 1418–1417, 1385–1370, and 1126–1085 cm−1 were employed. Semiquantitative determination by measurement of the absorbance at 3005.6 cm−1 is proposed, using the equation y=0.0071x+0.1301 (R2=0.983, SE=0.012). The percentage of lard in lard/GF blends was also correlated to the absorbance at 1417.85 cm−1 (y=0.0053x+0.0821, with R2=0.9233, SE=0.019) and at 1377.58 cm−1 (y=0.0069x+0.1327, with R2=0.9426, SE=0.022). For blends of lard with cow body fat (CBF) bands in the range 3008–3006 cm−1 and at 1417.8 and 966 cm−1 were used for qualitative detection. The equation y=−0.005x+0.3188 with R2=0.9831 and SE=0.0086 was obtained for semiquantitative determination at 966.22 cm−1.
A comparative study of mayonnaise and italian dressing prepared with lipase‐catalyzed transesterified olive oil and caprylic acid
Authors: Fomuso Lydia B. , Corredig Milena , Akoh Casimir C.
Published: November 2006

Viscoelastic properties of mayonnaise and Italian salad dressing prepared with olive oil and enzymatically synthesized structured lipid (SL) from caprylic acid and olive oil were studied using an SR5000 dynamic stress rheometer. Storage modulus (G′) and loss modulus (G″) were determined as functions of frequency, temperature, and stress. Frequency sweeps did not show significant differences between dressings prepared with olive oil or SL. For all mechanical spectra, G′ values were consistently higher than G″ values. Both Italian dressing and mayonnaise samples displayed similar gel‐like characteristics. Mayonnaise and Italian dressings made with olive oil separated when they were brought to room temperature from refrigeration temperatures. SL‐based mayonnaise did not separate. Only minor separation was observed in SL‐based Italian dressing. A change in the crystallization properties of the two oils was probably responsible for the differences observed after refrigeration. Both SL‐based and unmodified olive oil‐based mayonnaise and Italian dressing samples had similar viscoelastic character.
A new method for estimating solubility of fatty acids, esters, and triglycerides in supercritical carbon dioxide
Authors: Vasconcellos Vanessa R. , Cabral Fernando A.
Published: November 2006

A method to predict solubility of fat compounds (fatty acids, fatty acid esters, and triglycerides) in supercritical CO2 in the absence of experimental data is presented. The method is based on the idea of group contribution, so only knowledge about the chemical structure of the substance is needed to predict its solubility in CO2. Chrastil's equation was used to correlate the solubilities of fatty acids, fatty acid esters, and triglycerides in CO2. The three parameters determined from fitting of the data were calculated. A nonlinear fit routine was used to determine the chemical group contributions to the three parameters. Analysis of the results shows that it is possible to correlate the parameters of Chrastil's equation to molecular groups. The average deviation from the experimental data was 8%.
The effect of carotene extraction system on crude palm oil quality, carotene composition, and carotene stability during storage
Authors: Baharin B. S. , Latip R. A. , Che Man Y. B. , Rahman R. Abdul
Published: November 2006

Palm carotene was successfully concentrated from crude palm oil (CPO) by an adsorption process using a synthetic adsorbent followed by solvent extraction. Evaluation of feed CPO and CPO which underwent the carotene extraction process was conducted. The quality of CPO after the extraction process was slightly deteriorated in terms of free fatty acid, moisture content, impurities, peroxide value, anisidine value, discriminant function, and deterioration of bleachability index. However, the CPO still can be refined to produce refined, bleached, deodorized palm oil that meets the Palm Oil Refiners Association of Malaysia specifications. No extra cost was incurred by refining this CPO as the dosage of bleaching earth used was very similar to the refining of standard CPO. The triglyceride carbon number and fatty acid composition of CPO after going through the carotene extraction process were almost the same as CPO data. The major components of the carotene fraction were similar to CPO, which contains mainly α‐ and β‐carotene. The carotene could be stored for at least 3 mon.
Comparison of flavor compounds of potato chips fried in palmolein and silicone fluid
Authors: Martin Fiona L. , Ames Jennifer M.
Published: November 2006

The importance of the frying oil as a heat‐transfer medium and as a source of flavor precursors for the formation of potato chip flavor was investigated. Potato slices were fried in palmolein or silicone fluid, and the volatile flavor compounds of the resulting chips were isolated onto Tenax and analyzed by gas chromatography‐mass spectrometry. Although the heat‐transfer coefficients of the oils did not differ significantly, their temperature profiles during frying were different, probably due to greater turbulence on placing potato slices in palmolein, leading to more efficient heat transfer. Levels of Strecker aldehydes and sulfides in chips fried in the two media were not significantly different, but levels of pyrazines were significantly higher in palmolein‐fried chips. Amounts of 2,4‐decadienal were also significantly higher in palmolein‐fried chips, but there was no significant difference in hexanal levels between the samples.
Effect of temperature on recrystallization behavior of cocoa butter
Authors: van Langevelde Arjen , Van Malssen Kees , Peschar René , Schenk Henk
Published: November 2006

Crystallization of cocoa butter in the β phase directly from the melt is only possible by employing the memory effect of cocoa butter. Cocoa butter crystallized in the β phase, heated to the so‐called maximal temperature (just above its melting end point), recrystallizes in the β phase after cooling to a crystallization temperature. The influence of the maximal and crystallization temperatures on the recrystallization behavior has been investigated for two cocoa butters. Rapid‐starting recrystallization into the β(VI) phase and slow‐starting recrystallization into the β(V) have been observed. It is concluded that rapid‐starting recrystallization is induced by high‐melting 1,3‐distearoyl‐2‐oleoyl‐glycerol (SOS)‐rich crystals. The two β phases were identified by X‐ray powder diffraction and melting ranges. However, the X‐ray powder diffraction patterns for the β phases depended on the composition of the cocoa butter and on the crystallization method used. Therefore, it was not possible to take any particular β(VI) X‐ray powder diffraction pattern as a standard for the β(VI) phase of all cocoa butters.
Influence of thermal conditions and presence of additives on fat bloom in chocolate
Authors: Walter Peggy , Cornillon Paul
Published: November 2006

This study focused on the analysis of the effects of thermal history and presence of additives on fat bloom in chocolate. Magnetic resonance data obtained on specific chocolate samples were useful in evaluating the effect of thermal history on the appearance of fat bloom and also in understanding the underlying mechanism. Fat bloom was induced by thermal history such as storage for 3 d at 32 or 28°C. Increasing storage time at 21°C after each thermal treatment also promoted fat bloom. Differential scanning calorimetry experiments confirmed the appearance of polymorphic form VI in the bloomed samples. Also, three different components were added separately to the initial composition of dark chocolate and the appearance of fat bloom was monitored. 1,3‐Dibehenoyl, 2‐oleoylglycerol (BOB) did prevent fat bloom. However, magnetic resonance and differential scanning calorimetry data collected on chocolate samples did not confirm that either added sucrose or milk powder prevented fat bloom. Indeed, fat bloom occurred for these samples, but its characteristics were different from those with pure chocolate.
Quantitation of acyl migration during lipase‐catalyzed acidolysis, and of the regioisomers of structured triacylglycerols formed
Authors: Mu Huiling , Kurvinen Juha‐Pekka , Kallio Heikki , Xu Xuebing , Høy Carl‐Erik
Published: November 2006

Various MLM‐type (M, medium‐chain fatty acids; L, long‐chain fatty acids) structured triacylglycerols were produced in pilot‐ or small‐scale packed‐bed reactors by lipasecatalyzed acidolysis. The incorporation and acyl migration of octanoic acid were measured by gas chromatography and Grignard degradation, and ranged from 39.0 to 48.7% and 0.6 to 9.3%, respectively. Quantitation of triacylglycerol molecular species was performed by ammonia negative ion chemical ionization (NICI) mass spectrometry (MS). The proportion of ACN (acyl carbon number) 34 species that contained one C18 fatty acid and two C8∶0′ in samples analyzed, varied from 12.5 to 23.2%. The selected regioisomers MLM and MML within the ACN 34 species group were quantified by NICI tandem MS (MS/MS) and were in the range of 97.1 to 98.4% and 1.6 to 2.9%, respectively. There was no correlation between the level of acyl migration during lipase‐catalyzed esterification and the level of regioisomers of the selected MLM‐type triacylglycerols in the structured lipid samples.
Reactivity of medium‐chain substrates in the interesterification of tripalmitin catalyzed by papaya lipase
Authors: Gandhi Neena N. , Mukherjee Kumar D.
Published: November 2006

Reactivity of different medium‐chain substrates, i.e., n‐octanol, caprylic acid, and its alkyl (methyl, ethyl, n‐propyl, and n‐butyl) esters, was assessed in the interesterification of tripalmitin catalyzed by papaya (Carica papaya) lipase. Alcoholysis with n‐octanol was the fastest reaction leading to the highest conversion of tripalmitin to n‐octyl palmitate and concomitant formation of di‐ as well as monopalmitoylglycerols. This was followed by transesterification of tripalmitin with n‐butyl and n‐propyl caprylates, which in turn were faster than transesterification with ethyl and methyl caprylates, yielding in each case the corresponding alkyl palmitates and triacylglycerols containing palmitoyl and capryloyl moieties as the major reaction products. Acidolysis of tripalmitin with caprylic acid yielded palmitic acid and triacylglycerols containing palmitoyl and capryloyl moieties as the major reaction products, however, with the lowest conversion among the three interesterification reactions studied. In each case, interesterification was accompanied by some hydrolysis of tripalmitin.