bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic esterification of dihydroxystearic acid
Authors: Awang R. , Basri M. , Ahmad S. , Salleh A. B. 
Published: November 2006

AbstractDihydroxystearic acid (DHSA) ester was synthesized enzymatically to overcome the problems associated with chemical processes. Immobilized enzyme, Lipozyme IM and Novozym 435, were employed as catalysts in the esterification reaction between DHSA and monohydric alcohol. Various factors that may affect the esterification reaction were studied, such as initial water content (aw), organic solvent, substrate concentration and the influence of alcohol chain length. It was found that the percent conversion was higher in organic solvents with log P (the logarithm of the partition coefficient of solvent in octanol/water system) from 2.0 to 4.0. The reaction was not affected by aw from 0.09 to 0.96. Increasing the mole ratio of alcohol to acid above 2.0 did not increase the percent converions of ester. The ester was identified by Fourier transform infrared and 13C nuclear magnetic resonance spectroscopy.
Nucleation kinetics of emulsified triglyceride mixtures
Authors: Kloek William , Walstra Pieter , van Vliet Ton 
Published: November 2006

AbstractThe purpose of this study is to determine character istic nucleation parameters such as the surface free energy for nucleus formation in mixtures of fully hydrogenated palm oil (HP) in sunflower oil (SF). These parameters will be used to model the bulk crystallization kinetics of the same mixtures. This was achieved by determining the crystallization kinetics in emulsified triglyceride mixtures using differential scanning calorimetry, proton nuclear magnetic resonance, and ultrasound velocity measurements. The latter technique appeared to be very sensitive for monitoring the crystallization kinetics of fat dispersions containing triglycerides with a simple phase behavior. Isothermal crystallization of emulsified HP stabilized by sodium caseinate started at 7 K below the α clear point, and the kinetics were best fitted assuming heterogeneous nucleation. Isothermal crystallization of emulsified 10% HP in SF stabilized by caseinate started at 14 K below the α melting point, and the kinetics were best fitted assuming homogeneous nucleation. If the same dispersion was stabilized by Tween 20, crystallization started at 11 K below the α melting point, and the kinetics were fitted best using heterogeneous nucleation. Analysis of the temperature dependency of the fit parameters yielded a surface free energy of a nucleus of about 4 mJ.m−2 in the case of homogeneous nucleation. Pre‐exponential nucleation frequencies indicated that a large proportion of the triglyceride molecule should be in the right conformation to be incorporated in a nucleus.
Trans fatty acid composition and tocopherol content in vegetable oils produced in Mexico
Authors: Medina‐Juárez L. A. , Gámez‐Meza N. , Ortega‐García J. , Noriega‐Rodriguez J. A. , Angulo‐Guerrero O. 
Published: November 2006

AbstractThe purpose of this study was to evaluate the trans fatty acid (TFA) composition and the tocopherol content in vegetable oils produced in Mexico. Sample oils were obtained from 18 different oil refining factories, which represent 72% of the total refineries in Mexico. Fatty acids and TFA isomers were determined by gas chromatography using a 100‐m fused‐silica capillary column (SP‐2560). Tocopherol content was quantified by normal‐phase high‐performance liquid chromatography using an ultraviolet detector and a LiChrosorb Si60 column (25 cm). Results showed that 83% of the samples corresponded to soybean oil. Seventy‐two percent of the oils analyzed showed TFA content higher than 1%. Upon comparing the tocopherol contents in some crude oils to their corresponding deodorized samples, a loss of 40–56% was found. The processing conditions should be carefully evaluated in order to reduce the loss of tocopherols and the formation of TFA during refining.
Acid‐treated soy hull carbon structure and adsorption performance
Authors: Hong Yan , Proctor Andrew , Shultz John 
Published: November 2006

AbstractThe objective of this study was to evaluate the effect of 14 N phosphoric acid and 12 N hydrochloric acid treatments on soy hull carbon structure and adsorption performance. Scanning electron micrographs showed that acid treatments disrupted the carbon structure whereas X‐ray diffraction data indicated that hydrochloric acid had a greater effect than phosphoric acid in creating a more amorphous carbon structure. Both acids significantly reduced carbon pH from 9.8, but hydrochloric acid reduced the pH to a much greater degree (pH 2.77) than phosphoric acid (pH 5.95). Both acids increased the carbon titratable surface charge. The greatest increase was in surface lactone and phenol groups, but increases were also seen in noncarboxylic carbonyls and the generation of carboxyls. Acidified carbon was most effective as a phospholipid adsorbent, and its lower affinity for other oil components may be due to competitive adsorption. Nonacidified carbon and hydrochloric acid‐treated carbon adsorbed most free fatty acids, whereas the nonacidified control and commercial carbon control were most effective at adsorbing peroxides. However, vacuum adsorption conditions alone increased the contents of saturated carbonyls that were probably formed by peroxide cleavage.
Enzymatic resolution of racemic secondary alcohols by lipase B from Candida antarctica
Authors: Patel Ramesh N. , Banerjee Amit , Nanduri Venkata , Goswami Animesh , Comezoglu F. T. 
Published: November 2006

AbstractChiral intermediates S‐(+)‐2‐pentanol and S‐(+)‐2‐heptanol were prepared by a lipase‐catalyzed enzymatic resolution proces. Among various lipases evaluated for the stereoselective acylation of racemic alcohols, lipase B from Candida antarctica catalyzed the acylation of the undesired enantiomer of racemic alcohols leaving the desired S‐(+)‐alcohols unreacted. A reaction yield of 43–45% and an enantiomeric excess (e.e.) of >99% were obtained for S‐(+)‐2‐pentanol or S‐(+)‐2‐heptanol when the reaction was carried out using vinyl acetate or succnic anhydride as acylating agent. In an alternative process, an enantioselective hydrolysis of 2‐pentyl acetate was demonstrated using lipase B giving S‐(+)‐2‐pentyl acetate and R‐(−)‐2‐pentanol. A reaction yield of 45% and an e.e. of 98.6% were obtained for S‐(+)‐2‐pentyl acetate.
Site‐directed mutagenesis of a highly active Staphylococcus epidermidis lipase fragment identifies residues essential for catalysis
Authors: Chang Rey‐Chang , Chou Shu‐Jen , Shaw Jei‐Fu 
Published: November 2006

AbstractA fragment of Staphylococcus epidermidis lipase gene (Lys‐303 to Lys‐688) was inserted into plasmid pET‐20b(+). The resulting C‐terminal His‐tagged recombinant protein (43 kDa) was overexpressed in Escherichia coli BL21(DE3) as a highly active lipase and was purified with nickel‐coupled resin. Putative catalytic sites were determined by site‐directed mutagenesis. Mutant enzymes (S418C and H648K) lost enzyme activities, which strongly suggests that the proposed residues of Ser‐418 and His‐648 are involved in catalysis. Site‐directed mutagenesis showed that in comparison with wild‐type enzyme, the M419A and V649l enzymes showed a 2.0‐ and 4.0‐fold increase in the kcat/Km′ respectively, but the M419l, M419Q, V649A, and V649L variants lost enzyme activities. The wild‐type enzyme and the V649l mutant favored the hydrolysis of p‐nitrophenyl esters of butyrate, but the M419A favored decanoate. The results suggested that the amino acid residues (Met‐419 and Val‐649), following the catalytic triad, could affect the substrate specificity and/or catalytic efficiency.
Identification of diacylglycerols and triacylglycerols in a structured lipid sample by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry
Authors: Mu Huiling , Sillen Henrik , Hiy Carl‐Erik 
Published: November 2006

AbstractAtmospheric pressure chemical ionization liquid chromatography/mass spectrometry was used in the identification of diacylglycerol and triacylglycerol (TAG) molecular species in a sample of a structured lipid. In the study of acylglycerol standards, the most distinctive differences between the diacylglycerol and TAG molecules were found to be the molecular ion and the relative intensity of monoacylglycerol fragment ions. All saturated TAG ranging from tricaproin to tristearin, and unsaturated TAG including triolein, trilinolein, and trilinolenin, had ammonium adduct molecular ions [M+NH4]+. Protonated molecular ions were also produced for TAG containing unsaturated fatty acids and the intensity increased with increasing unsaturation. Diacylglycerol fragment ions were also formed for TAG. The ammonium adduct molecular ion was the base peak for TAG containing polyunsaturated fatty acids, whereas the diacylglycerol fragment ion was the base peak for TAG containing saturated and monounsaturated medium‐ and long‐chain fatty acids; the relative intensities of the ammonium adduct molecular ions were between 14 and 58%. The most abundant ion for diacylglycerols, however, was the molecular ion [M−17]+, and the relative intensity of the monoacylglycerol fragment ion was also higher than that for TAG. These distinctive differences between the diacylglycerol and TAG spectra were utilized for rapid identification of the acylglycerols in the sample of a structured lipid.
Trans determination of edible oils by fourier transform near‐infrared spectroscopy
Authors: Li Hui , van de Voort F. R. , Ismail A. A. , Sedman J. , Cox R. 
Published: November 2006

AbstractA generalized partial‐least‐squares calibration for determination of the trans content of edible fats and oils by Fourier transform near‐infrared (FT‐NIR) spectroscopy using 8‐mm disposable glass vials for sample handling and measurement was developed. The trans contents of a broad range of oils were determined using the American Oil Chemists' Society single‐bounce horizontal attenuated total reflectance (SB‐HATR) mid‐infrared spectroscopic procedure, these trans reference data were used in the development of the generalized FT‐NIR calibration. Additional refined and product‐specific calibrations were also developed, and all the calibrations were assessed for their predictive capabilities using two sets of validation samples, one comprising a broad range of oil types and the other restricted to oils with specific characteristics. The FT‐NIR trans predictions obtained using the generalized calibration were in good agreement with the SB‐HATR results; the values were accurate and reproducible to within ±1.1 and ±0.5% trans, respectively, compared to a reproducibility of ±0.40% trans obtained for the SB‐HATR method. The accuracy of the predictions obtained from the generalized FT‐NIR calibration for particular oil types was not significantly improved by supplementing the base training set with samples of these specific types. Calibrating only these oil types did, however, produce a substantial improvement in predictive accuracy, aproaching that of the SB‐HATR method. These product specific calibrations produced serious predictive errors when nonrepresentative samples were analyzed. The incorporation of a supplementary discriminate analysis routine was found to be a powerful safeguard in flagging nonrepresentative samples as outliers and could also be used to select the calibration most appropriate for the characteristics of the sample being analyzed. Overall, it was concluded that FT‐NIR spectroscopy provides a viable alternative to the SB‐HATR/mid‐Fourier transform infrared method for trans determination, making use of more industrially robust instrumentation and equipped with a simpler sample handling system.
Optimization and validation of high‐performance liquid chromatographic method for the determination of dowtherm ATM in edible oils and oleochemicals
Authors: Moh M. H. , Tang T. S. , Tan G. H. 
Published: November 2006

AbstractA method using high‐performance liquid chromatography and fluorescence detection is optimized and validated for the determination of Dowtherm ATM in spiked oleochemicals and edible oils. The samples are directly injected into a reversed‐phase C18 column, and Dowtherm A is detected using a fluorescence detector set at 247 nm excitation and 310 nm emission wavelengths. The simple isocratic mobile phase used is a mixture of methanol and water (90∶10, vol/vol) at a flow rate of 1 mL/min. The limits of quantitation are from 0.1 to 0.2 μg/g. Mean recoveries ranged from 93.0 to 116% with reproducibilities of 1.29–3.84%. The procedure provides a simple, reliable and sensitive method for determining Dowtherm A residue in oleochemicals and edible oils without prior sample cleanup or extraction.
Enzymatic acidolysis of tristearin with lauric and oleic acids to produce coating lipids
Authors: Sellappan Subramani , Akoh Casimir C. 
Published: November 2006

AbstractTriacylglycerols with potential for coating application were prepared by acidolysis of tristearin with lauric and oleic acids using Lipozyme IM60 lipase in n‐hexane. The effects of reaction parameters such as time, temperature, substrate mole ratio, water content, enzyme load, and enzyme reuse were studied. Five‐gram scale synthesis was carried out to obtain the melting profile of products by differential scanning calorimetry (DSC). An acceptable melting profile was obtained for the product obtained with a 1∶4∶1 (tristearin/lauric acid/oleic acid) mole ratio of reactants. The DSC melting peak for this product was 31.4°C. Synthesis of 1200 g of this product was carried out at a 1∶4∶1 substrate ratio in a stirred tank batch reactor under optimal conditions. The reaction product, purified by short‐path distillation, was coated onto crackers and studied for its moisture inhibition ability, under water vapor‐saturated atmosphere, in a desiccator over different time intervals. The effectiveness of the synthesized lipid as a coating material was compared against uncoated crackers as a control and with cocoa butter‐coated crackers. The synthesized lipid was better in preventing moisture absorption than cocoa butter.
Optimization of physicochemical changes of palm olein with phytochemical antioxidants during deep‐fat frying
Authors: Jaswir Irwandi , Che Man Yaakob B. , Kitts David D. 
Published: November 2006

AbstractResponse surface methodology (RSM) was used to optimize the amounts of rosemary and sage extracts together with citric acid as synergist antioxidants in stabilizing refined, bleached, and deodorized palm olein during repeated deep‐fat frying of potato chips. For all physicochemical properties studied, these phytochemical antioxidant treatments significantly (P<0.05) reduced the oxidation rate of the oil. During 5 d of frying, anisidine value, peroxide value, free fatty acid, polymer content, color units, viscosity, and absorbances at 232 and 268 nm gradually increased, whereas iodine value and ratio of 18∶2/16∶0 decreased. Further statistical analyses, including coefficient of determination (R2) and probability of F values, indicated that mathematical models for each physicochemical parameter could be developed confidently in this study, with R2 for all parameters greater than 0.90. These results suggested that an optimal mixture of phytochemical antioxidants derived from rosemary and sage together with citric acid could be produced using RSM for stabilizing thermally processed oil. For many physicochemical parameters examined, the use of moderate levels of antioxidants could result in optimal responses.
Use of high‐resolution 13C nuclear magnetic resonance spectroscopy for the screening of virgin olive oils
Authors: Zamora Rosario , Alba Virginia , Hidalgo Francisco J. 
Published: November 2006

Abstract13C Nuclear magnetic resonance (NMR) spectra of 104 oil samples were obtained and analyzed in order to study the use of this technique for routine screening of virgin olive oils. The oils studied included the following: virgin olive oils from different cultivars and regions of Europe and north Africa, and refined olive, “lampante” olive, refined olive pomace, high‐oleic sunflower, hazelnut, sunflower, corn, soybean, rapeseed, grapeseed, and peanut oils, as well as mixtures of virgin olive oils from different geographical origins and mixtures of 5–50% hazelnut oil in virgin olive oil. The analysis of the spectra allowed us to distinguish among virgin olive oils, oils with a high content of oleic acid, and oils with a high content of linoleic acid, by using stepwise discriminant analysis. This parametric method gave 97.1% correct validated classifications for the oils. In addition, it classified correctly all the hazelnut oil samples and the mixtures of hazelnut oil in virgin olive oil assayed. All of these results suggested that 13C NMR may be used satisfactorily for discriminating some specific groups of oils, but to obtain 100% correct classifications for the different oils and mixtures, more information than that obtained from the direct spectra of the oils is needed.
Thermal gradient deacidification of crude rice bran oil utilizing supercritical carbon dioxide
Authors: Dunford Nurhan Turgut , King Jerry W. 
Published: November 2006

AbstractThe effect of isothermal and temperature gradient operation of a supercritical fluid fractionation column on the composition of rice brain oil (RBO) fractions has been studied. Application of a temperature gradient along the column was found to be beneficial in reducing the triacylglycerol (TAG) lost in the extract fraction. Utilization of higher temperature in the stripping section improved free fatty acid (FFA) removal from crude RBO. FFA acid content of the extract increased, and TAG content decreased with respect to time during the fractionation runs. Increasing the CO2 flow rate from 1.2 to 2 L/min did not affect the extract composition significantly. By using the above approach, it is possible to obtain RBO fractions with similar total sterol ester content [∼23 high‐performance liquid chromatographic area (HPLC) %, ferulic plus fatty acid esters] to that of the commercially available sterol ester‐enriched (ca. 21 HPLC area % fatty acid esters) margarines/spreads.
Change in the natural ratio between chlorophylls and carotenoids in olive fruit during processing for virgin olive oil
Authors: Roca Mar a , nguez‐Mosquera M». Isabel M 
Published: November 2006

AbstractDifferent varieties of olives from different sources, harvested in a similar ripeness state, have been characterized by their chlorophyll and carotenoid pigment profile and content. Pigment richness is inherent to the variety and enables great differences or similarities to be established between them. In all the fruits, ripening involves pigment loss, with the disappearance of chlorophylls always being slightly greater than that of carotenoids. However, independently of variety and the different pitment content of the fruits, the ratio between chlorophylls and carotenoids tends to remain more or less constant, within a range of 2.5 to 3.7 mg total chlorophyll/mg total carotenoid. Pigment loss caused by the extraction process is more marked for the chlorophyll fraction than for the carotenoids, changing the ratio in the oil to around one unit, whatever the variety of soruce fruit.
Calcium carbonate catalyzed alcoholysis of fats and oils
Authors: Suppes G. J. , Bockwinkel K. , Lucas S. , Botts J. B. , Mason M. H. , Heppert J. A. 
Published: November 2006

AbstractSeveral alcoholysis catalysts, known to be effective for reactions between simple alcohols and soybean oil, were evaluated and found to be ineffective toward alcoholysis of ethylene glycol with soybean oil under traditional reaction conditions. An initial survey of alternative catalysts revealed that organometallic tin complexes were effective but unsatisfactory due to toxicity and difficulty in recovering the catalyst. Satisfactory performance for several alcoholysis reactions was achieved with calcium carbonate catalysts even though at higher temperatures, typically greater than 200°C. Higher reaction temperatures are not considered to be a problem for flow reactors where heat exchangers can be readily used to minimize energy costs. Free fatty acids were esterified by the calcium carbonate and did not appear to inhibit the catalyst. Reaction times of 18 min provided essentially complete conversion. No decrease in the activity of calcium carbonate was observed after weeks of utilization. The robust structure is suitable for use in packed‐bed reactors. The catalyst used for the flow reactors was pulverized limestone. Limestone from two locations was tested and found to be effective. Catalyst removal requires only a screening process at the reactor discharge.
Production of sugar fatty acid estrs by enzymatic esterification in a stirred‐tank membrane reactor: Optimization of parameters by response surface methodology
Authors: Yan Youchun , Bornscheuer Uwe T. , Stadler Gerhard , Lutz‐Wahl Sabine , Reuss Matthias , Schmid Rolf D. 
Published: November 2006

Abstract6‐O‐β‐D(+)‐Glucose stearate serving as a model product of glucose fatty acid monoesters was synthesized using lipase B from Candiada antarctica (Chirazyme® L‐2) in a mainly solid‐phase system in a stirred‐tank membrane reactor. Esterification was performed in the presence of a small amount of ethyl methylketone (EMK), maintaining a catalytic liquid phase as well as forming an azeotrope with the reaction water. The azeotrope was evaporated and broken by membrane vapor permeation, then the dried EMK was returned to the reaction medium. The process was optimized by response surface methodology based on five major reaction parameters [time (T), substrate ratio (acyl donor to glucose, Sr, temperature (Rt), amount of solvent [solvent to substrates, [w/w], Sa), and enzyme load (El)] varied at three levels, resulting in higher yields. Thus, under optimized conditions [Tr=58 h; Sr=2.7; El=8.9% (w/w); Rt=78°C; Sa=1.9], up to 93% yields of glucose stearate were achieved.
Relationship between characteristics of oil droplets and solidification of thermally treated creams
Authors: Mutoh Taka‐Aki , Nakagawa Shinsuke , Noda Masayuki , Shiinoki Yasuhiko , Matsumura Yasuki 
Published: November 2006

AbstractThe relationship between the characteristics of oil droplets and the change in appearance of cream was investigated. The model creams (40 wt% oil‐in‐water emulsion), similar to commerical products, were prepared with vegetable fat, milk protein, and emulsifier. The thermal treatment, in which the cream was exposed to a certain temperature and subsequently recooled, was performed on the assumption that the temperature was temporarily elevated during transportation and storage of commercial products. Solidification of the cream was observed when it was exposed to a temperature where there was a small percentage in solid fat content (SFC) of fat in oil droplets and recooled, whereas the cream remained in the liquid state when it was exposed to the temperature where SFC was zero and recooled. When the SFC of oil droplets was 0% at the treated temperature, greater supercooling prior to fat crystallization occurred and the crystallization rate after the initial formation of crystals was much higher. On the other hand, the polymorphism of fat in the droplets was not directly affected by the thermal treatment. These results indicate that the crystallization in oil droplets at the heating temperature may be closely connected with the destablization of oil droplets via a partial coalescence mechanism, which will cause the solidification of cream.