bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic determination of the effect of shear on lipid crystallization
Authors: Garbolino Chiara , Ziegler Gregory R. , Coupland John N. 
Published: November 2006

AbstractThe design and calibration of a novel rheometer incorporating ultrasonic sensors are described. The instrument is capable of the simultaneous measurements of torque, rate of temperature change, and ultrasonic properties of a liquid as a function of time, temperature, and shear rate. The effect of shear rate on the crystallization onset temperature of a sample of confectionery coating fat is studied using this device. The instrument detected the phase transition in the sheared sample as abrupt changes in all of the measured parameters. The onset temperature increased significantly with shear rate, implying lipid crystallization can be accelerated by mixing. There were also significant differences between sensing modalities.
Storage stability of milled flaxseed
Authors: Malcolmson L. J. , Przybylski R. , Daun J. K. 
Published: November 2006

AbstractTwo samples of flaxseed, Linott and a mixture of several varieties, were milled and stored at 23±2°C for 128 d in paper bags with plastic liners. Samples were evaluated at 0, 33, 66, 96, and 128 d for chemical, sensory, and volatile indicators of quality. Neither the mixed variety nor Linott samples showed a significant increase in peroxide values or conjugated double bonds throughout the 128‐d storage period. Only the Linott sample showed a significant increase in free fatty acids, which was likely due to the presence of immature seed in the sample. Total volatiles increased with storage in the mixed variety sample but showed minimal change in the Linott sample. Overall, the levels of total volatiles in the milled flaxseed samples were much lower than levels reported in stored vegetable oils containing significantly lower levels of linolenic acid. Dienals, formed during polyunsaturated fatty acid oxidation, and hexanal, a compound used as an indicator of oxidative deterioration, were found at very low levels in both samples and did not reach high levels throughout the 128‐d storage period. A trained sensory panel could not detect any differences in the odor properties of fresh or stored milled samples. No differences in flavor could be detected between bread made with 0‐ and 128‐d milled flaxseed. This study showed that milled flaxseed can be stored up to 4 mon at ambient temperatures without noticeable changes in quality. The presence of endogenous antioxidants in the milled flaxseed may account for the stability observed.
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

AbstractThe 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

AbstractRapeseed 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

AbstractA 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

AbstractInterest 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

AbstractResponse 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

AbstractEvaluation 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

AbstractThe 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

AbstractMinor 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

AbstractThis 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

AbstractLipase 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

AbstractThere 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

AbstractRice 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

AbstractWheat 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

AbstractDifferent 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

AbstractThe 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.