bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of hydroperoxides by fourier transform infrared spectroscopy with a disposable infrared card
Authors: Ma K. , van de Voort F. R. , Ismail A. A. , Sedman J. 
Published: May 2007

AbstractDisposable polyethylene infrared cards (3M IR cards) were investigated for their suitability for the quantitative determination of peroxide value (PV) in edible oils relative to a conventional transmission flow cell. The analysis is based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine oxide (TPPO). Preliminary work indicated that the cards, although relatively consistent in their pathlength (±1%), had an overall effective pathlength variation of ±∼5%, caused by variability in loading of the oil onto the cards. This loading variability was reduced to <0.5% by developing a normalization protocol that is based on the peak height of the ester linkage carbonyl overtone band at 3475 cm−1, which allowed one to obtain consistent and reproducible spectra. The standard PV calibration approach, based on the TPPO peak height at 542 cm−1, failed because of unanticipated card fringing in the region where the measurements were being made. However, the development of a partial‐least‐squares (PLS) calibration provided a means of eliminating the interfering effect of the fringes and allowed the TPPO band to be measured accurately. An alternate approach to the standardized addition of TPP reagent to the oil was also investigated by impregnating the 3M IR cards with TPP, thus allowing the reaction to take place in situ. The spectral analysis protocols developed (normalization/calibration) were programmed to automate the PV analysis completely. The 3M card‐based Fourier transform infrared PV methods developed were validated by analyzing oxidized oils and comparing the PV predictions obtained to those obtained in a 100‐µm KCI flow cell. Both card methods performed well in their ability to predict PV. The TPP‐impregnated 3M card method reproduced the flow cell PV data to within ±1.12 PV, whereas the method with an unimpregnated card was accurate to ±0.92 PV over the calibrated range (0–25 PV). Our results indicate that, with spectral normalization and the use of a PLS calibration, quantitative PV data, comparable to those obtained with a flow cell, can be provided by the 3M IR card. With the analytical protocol preprogrammed, the disposable 3M card provides a simple, rapid and convenient means of carrying out PV analyses, suitable for quality control laboratories, taking about 2–3 min per analysis.
Thermal degradation of single methyl oleate hydroperoxides obtained by photosensitized oxidation
Authors: Lercker Giovanni , Bortolomeazzi Renzo , Pizzale Lorena 
Published: May 2007

AbstractA peroxidation mixture containing methyl 9‐ and 10‐hydroperoxy‐trans‐octadecenoates (MOHP) was obtained by singlet oxygen oxidation of methyl oleate. The two hydroperoxides were collected by solid phase extraction and purified separately by high‐performance liquid chromatography. Identification and single‐isomer purity evaluations were carried out by comparing the chromatographic and gas chromatography‐mass spectrometry parameters of the corresponding reduced hydroxy derivatives. Each purified MOHP was thermally degraded and new reaction mechanisms were proposed from the identification of the degradation products. Thermal rearrangement of each hydroperoxide isomer involved an allylic 3‐carbon intermediate before further degradation steps. The two MOHP isomers obtained from singlet oxygen oxidation produced all eight hydroperoxide isomers by thermal degradation in the condensed phase at high temperature (200°C). This result supports the assumption of singlet oxygen as a promoter of the first steps of oxidation of food lipids and also reconsiders the Khan mechanism.
Oxidative and flavor stability of oil from lipoxygenase‐free soybeans
Authors: King J. M. , Svendsen L. K. , Fehr W. R. , Narvel J. M. , White P. J. 
Published: May 2007

AbstractSoybeans that lack or contain three lipoxygenase (LOX) isozymes, LOX‐1, LOX‐2, and LOX‐3, were evaluated for oxidative and flavor stability at 60°C in the dark and at 35°C in the light. Although the two types of soybeans had a similar genetic background, there were significant differences (P ≤ 0.01) in fatty acid percentages between the lipoxygenase‐free and normal oils before and after storage at both temperatures. The linolenic acid content of oil from LOX‐free germplasm before storage averaged 7.2%, while normal lines averaged 6.6%. The linoleic acid content after storage averaged 6.9% for LOX‐free and 6.6% for normal oils. LOX‐free oil was not significantly different from normal oil in flavor, as judged by a sensory panel, or in concentrations of volatiles during storage at either storage condition. LOX‐free oil had less hexanal than normal oil before storage, but had significantly greater (P ≤ 0.05) levels after storage for two weeks at 35°C. Peroxide values of oil from LOX‐free soybeans were significantly greater (P ≤ 0.01) than oil from the normal soybean after storage at 60 and 35°C. LOX‐free oil had significantly greater (P ≤ 0.01) levels of α‐, β‐, and γ‐tocopherols. In general, oil from LOX‐free soybeans did not have improved flavor or oxidative stability. Differences between the two oil types in peroxide value and in production of a few volatiles were probably a result of the differences in initial fatty acid composition.
Effect of initial slight oxidation on stability of polyunsaturated fatty acid/protein mixtures under controlled atmospheres
Authors: Alaiz Manuel , Hidalgo Francisco J. , Zamora Rosario 
Published: May 2007

AbstractA mixture of unsaturated fatty acids (FA), mainly linolenic acid, and bovine serum albumin (BSA) was incubated under several different atmospheres to study the effect of these atmospheres on the stability of FA to oxidation. Four experiments were carried out simultaneously, which consisted of the incubation of the FA/BSA mixture under air, nitrogen, air in the presence of 200 ppm of butylated hydroxytoluene, and air for 6 h and then under nitrogen. The four experiments were tested for lipid oxidation and color changes by measuring absorbances at 234 and 270 nm, formation of thiobarbituric acid‐reactive substances, and color differences and yellowness index. The samples that were oxidized with air before storage under nitrogen were the most stable against lipid peroxidation and exhibited the smallest color changes. These results suggest that a slight and controlled lipid oxidation improved the oxidative stability of FA/BSA mixtures.
Isolation of an active peptide fragment from human serum albumin and its synergism with α‐tocopherol
Authors: Hatate Hideo 
Published: May 2007

AbstractAn active peptide was isolated from hydrolysates of human serum albumin. This peptide was initially isolated by gel permeation chromatography and subsequent reversed‐phase high‐performance liquid chromatography. This active peptide, composed of 10 amino acid residues, was further hydrolyzed with a lysyl endopeptidase to give two peptide fragments. Only one fragment, identified as the tetrapeptide Leu‐Gln‐His‐Lys, was found to have activity comparable to the original peptide and corresponded to the amino acid residues 103–106 of human serum albumin. Among these four amino acid residues, the His‐Lys sequence seemed to be important in the occurrence of potent activity by comparison of the structural similarity with another active tetrapeptide, Asp‐Thr‐His‐Lys, which had been previously isolated from bovine serum albumin hydrolysates. In addition, the active fragment showed potent synergism by preventing consumption of α‐tocopherol during the autoxidation of linoleic acid.
Antioxidative activity of green tea catechin extract compared with that of rosemary extract
Authors: Chen Zhen‐Yu , Wang Li‐Ya , Chan Ping Tim , Zhang Zesheng , Chung Hau Yin , Liang Chao 
Published: May 2007

AbstractThis study compared the antioxidative activity of green tea catechin (GTC) extract with that of rosemary extract in canola oil, pork lard, and chicken fat. The GTC extract was obtained from jasmine and longjing green teas and mainly consisted of four epicatechin isomers including (−)epigallocatechin gallate (EGCG), (−)epigallocatechin (EGC), (−)epicatechin (EC), and (−)epicatechin gallate (ECG). The oxidation was conducted at 100 ± 2°C by monitoring oxygen uptake. The oxygen consumption test demonstrated that GTC extract was much more effective than the rosemary extract against lipid oxidation in canola oil, pork lard, and chicken fat under the conditions of the present study. Together with our previous study which showed that GTC extract was more protective than butylated hydroxytoluene as an antioxidant, these results suggest that GTC as a mixture of EGCG, EGC, EC, and ECG may serve as an antioxidant in processed foods.
Influence of lipase‐catalyzed interesterification on the oxidative stability of melon seed oil triacylglycerols
Authors: Moussata Charment O. , Akoh Casimir C. 
Published: May 2007

AbstractMelon seeds are rich in oil. However, the stability of melon seed oil (MSO) is low because of its high content of the essential fatty acid, linoleic acid (18:2n‐6). MSO was physically blended or enzymatically interesterified with higholeic sunflower oil (HOSO). The fatty acid composition of MSO was remarkably changed after interesterification. Palmitic (16:0), stearic (18:0), and oleic (18:1n‐9) acid contents increased at the sn‐2 position of triacylglycerols, whereas 18:2n‐6 decreased due to interesterification. The oxidative stability of the physical and Pseudomonas sp. (PS30) lipase‐interesterified blends was assessed with the Oxidative Stability Instrument, peroxide value, and conjugated diene methods. The stability of MSO increased with increased proportions of HOSO, which was the source of 18:1n‐9 in the blends. The ratio of 18:1n‐9/18:2n‐6 improved from 0.18 in MSO to 1.47 in the enzymatically interesterified blend. Calculated oxidizability and the results of oxidation tests of the blends confirmed the improvement in MSO stability by both physical blending and enzymatic interesterification.
Efficient intraliposomal entrapment of hydrophilic platinum oligonuclear complexes
Authors: Ogawa Yoshikatsu , Yamazaki Yoshimitsu , Kodaka Masato , Okuno Hiroaki 
Published: May 2007

AbstractA simple method for intraliposomal entrapment of platinum complexes is presented, where hydrophilic platinum oligonuclear complexes, 1‐methyluracil green (MeUG), uridine green (UdG) and uridine blue (UdB), are included inside liposomes and allowed to react with bilayer lipids. The liposomes prepared in this method exhibit higher entrapment efficiency and higher distribution to organs (liver, kidney, spleen, lung) and blood (but not B16 cancer cells) than those prepared from mononuclear Pt complexes [cis‐diamminedichloroplatinum, cis‐diammine‐1,1′‐dicarboxylatocyclobutaneplatinum, and cis‐dichloro‐cis‐dihydroxy‐trans‐bis(isopropylamine)platinum)].
Fast formation of high‐purity methyl esters from vegetable oils
Authors: Boocock David G. B. , Konar Samir K. , Mao V. , Lee C. , Buligan Sonia 
Published: May 2007

AbstractExperiments have confirmed that the base‐catalyzed methanolysis of vegetable oils occurs much slower than butanolysis because of the two liquid phases initially present in the former reaction. For the same reason, second‐order kinetics are not followed. The use of a cosolvent such as tetrahydrofuran or methyl tertiary butyl ether speeds up methanolysis considerably. However, like one‐phase butanolysis, one‐phase methanolysis initially exhibits a rapid formation of ester, but then slows drastically. Experiments show that the half‐life of the hydroxide catalyst is too long to explain the sudden slowing of the reaction. Similarly, lower rate constants for the methylation of the mono‐ and diglycerides are not a reasonable explanation. Instead the cause has been identified as the fall in polarity which results from the mixing of the nonpolar oil with the methanol. This lowers the effectiveness of both hydroxide and alkoxide catalysts. Increasing the methanol/oil molar ratio to 27 in the one‐phase system raises the polarity such that the methyl ester content of the ester product exceeds 99.4 wt% in 7 min. This has obvious implications for the size of new methyl ester plants as well as the capacity of existing facilities.
Low‐temperature property and engine performance evaluation of ethyl and isopropyl esters of tallow and grease
Authors: Wu Wen‐Hsin , Foglia Thomas A. , Marmer William N. , Dunn Robert O. , Goering Carroll E. , Briggs Thomas E. 
Published: May 2007

AbstractThree monoalkyl fatty acid esters derived from tallow and grease were prepared by lipase‐catalyzed transesterification and evaluated as prospective diesel engine fuels. The low‐temperature properties of the esters, both neat and as 20% blends in No. 2 diesel fuel, were evaluated. Those properties included cloud point, pour point, cold filter plugging point, low‐temperature flow test, and crystallization onset temperature. Other properties of the esters, such as kinematic viscosity, heating value, and calculated cetane number, also were determined. All three esters had acceptable physical and low‐temperature properties, as well as acceptable fuel properties at the 20% level in diesel blends. Engine performance and emissions for the ester blends were determined in a direct‐injection, matched two‐cylinder diesel engine. Among the monoalkyl esters studied, ethyl greasate had better properties and engine performance characteristics than the two tallow esters. For the latter esters, isopropyl tallowate had better properties than ethyl tallowate.
Production of specific‐structured lipids by enzymatic interesterification: Elucidation of acyl migration by response surface design
Authors: Xu X. , Skands A. R. H. , Høy C. ‐E. , Mu H. , Balchen S. , Adler‐Nissen J. 
Published: May 2007

AbstractProduction of specific‐structured lipids (SSL) by lipase‐catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of byproducts. In this paper, the elucidation of acyl migration by response surface design was carried out in the Lipozyme IM (Rhizomucor miehei)‐catalyzed interesterification between rapeseed oil and capric acid in solvent‐free media. A five‐factor response surface design was used to evaluate the influence of five major factors and their relationships. The five factors, water content, reaction temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points. All parameters besides substrate ratio had strong positive influences on acyl migration, and reaction temperature was most significant. The contour plots clearly show the interactions between the parameters. The migration rates of different fatty acids were also compared from three different sets of experiments during the lipase‐catalyzed reaction. The best‐fitting quadratic response surface model was determined by regression and backward elimination. The coefficients of determination (R2) of the model were 0.996 and 0.981 for Q2 value. The results show that the fitted quadratic model satisfactorily expresses acyl migration for the enzymatic interesterification in the batch reactor used.
Production of specific‐structured triacylglycerols by lipase‐catalyzed interesterification in a laboratory‐scale continuous reactor
Authors: Mu H. , Xu X. , Høy C. ‐E. 
Published: May 2007

AbstractA laboratory‐scale continuous reactor was constructed for production of specific structured triacylglycerols containing essential fatty acids and medium‐chain fatty acids (MCFA) in the sn‐2 and sn‐1,3 positions, respectively. Different parameters in the lipase‐catalyzed interesterification were elucidated. The reaction time was the most critical factor. Longer reaction time resulted in higher yield, but was accompanied by increased acyl migration. The concentration of the desired triacylglycerol (TAG) in the interesterification product increased significantly with reaction time, even though there was only a slight increase in the incorporation of MCFA. Increased reactor temperature and content of MCFA in the initial reaction substrate improved the incorporation of MCFA and the yield of the desired TAG in the products. Little increase of acyl migration was observed. Increasing the water content from 0.03 to 0.11% (w/w substrate) in the reaction substrate had almost no effect on either the incorporation or the migration of MCFA, or on the resulting composition of TAG products and their free fatty acid content. Therefore, we conclude that the water in the original reaction substrate is sufficient to maintain the enzyme activity in this continuous reactor. Since the substrates were contacted with a large amount of lipase, the reaction time was shorter compared with a batch reactor, resulting in reduced acyl migration. Consequently, the purity of the specific structured TAG produced was improved. Interesterification of various vegetable oils and caprylic acid also demonstrated that the incorporation was affected by the reaction media. Reaction conditions for lipase‐catalyzed synthesis of specific structured TAG should be optimized according to the oil in use.
Increasing short‐chain fatty acid yield during lipase hydrolysis of a butterfat fraction with periodic aqueous extraction
Authors: Lencki Robert W. , Smink Natasja , Snelting Heleen , Arul Joseph 
Published: May 2007

AbstractFactors affecting the release of short‐chain fatty acids during hydrolysis of a butterfat fraction with a 1,3‐positional and short‐chain‐specific Penicillium roqueforti lipase were investigated. When a short‐chain triglyceride fraction was used as substrate, as opposed to whole butterfat, the ratio of desirable flavor short‐chain free fatty acids (FFA) to undesirable medium‐chain FFA in the FFA fraction increased from 0.75 to 1.80. However, with both substrates, FFA accumulation eventually led to lipase inhibition and limited the total amount of triglyceride hydrolysis. This inhibition phenomenon was principally due to product inhibition. Periodically extracting the FFA with a buffer solution minimized this inhibition phenomenon, thereby significantly increasing lipase activity and the degree of triglyceride hydrolysis. Thus, on‐line extraction of FFA in lipase reactors has the potential of greatly increasing system productivity.
Parameters affecting the synthesis of geranyl butyrate by esterase 30,000 from Mucor miehei
Authors: Karra‐Chaabouni Maha , Pulvin Sylviane , Touraud Didier , Thomas Daniel 
Published: May 2007

AbstractThe factors affecting the synthesis of geranyl butyrate by esterase 30,000 of Mucor miehei were studied in a solvent‐free system. The effects of substrate molar ratio, temperature, agitation speed, and initial addition of water were investigated. The equimolar ratio was most interesting for ester production in batch. There were no diffusion limitations, and the reaction could be realized at low agitation. The catalytic activity of the enzyme was irreversibly deactivated at 60°C, and the initial addition of water decreased the rate of conversion after 75 h of reaction. The enzyme activity increased with increased linear chainlength of the acid and was also affected by the alcohol structure. Esterase 30,000 gave the highest conversion of butyric acid with hexanol and terpenic alcohols (citronellol, nerol) and the lowest with the secondary alcohol (2‐hexanol). Finally, five other industrial enzymatic preparations were investigated for their ability to synthesize geranyl butyrate and to hydrolyze olive oil. We observed, for the lipase from Rhizopus javanicua, that there is no relationship between hydrolytic and synthetic activities; this example shows that the hydrolytic lipase activity data cannot predict the capability of lipases in esterification reactions.
Enzymatic enrichment of arachidonic acid from Mortierella single‐cell oil
Authors: Shimada Yuji , Sugihara Akio , Minamigawa Yumi , Higashiyama Kenichi , Akimoto Kengo , Fujikawa Shigeaki , Komemushi Sadao , Tominaga Yoshio 
Published: May 2007

AbstractAn attempt was made to enrich arachidonic acid (AA) from Mortierella single‐cell oil, which had an AA content of 25%. The first step involved the hydrolysis of the oil with Pseudomonas sp. lipase. A mixture of 2.5 g oil, 2.5 g water, and 4000 units (U) Pseudomonas lipase was incubated at 40°C for 40 h with stirring at 500 rpm. The hydrolysis was 90% complete after 40 h, and the resulting free fatty acids (FFA) were extracted with n‐hexane (AA content, 25%; recovery of AA, 91%). The second step involved the selective esterification of the fatty acids with lauryl alcohol and Candida rugosa lipase. A mixture of 3.5 g fatty acids/lauryl alcohol (1:1, mol/mol), 1.5 g water, and 1000 U Candida lipase was incubated at 30°C for 16 h with stirring at 500 rpm. Under these conditions, 55% of the fatty acids were esterified, and the AA content in the FFA fraction was raised to 51% with a 92% yield. The long‐chain saturated fatty acids in the FFA fraction were eliminated as urea adducts. This procedure raised the AA content to 63%. To further elevate the AA content, the fatty acids were esterified again in the same manner with Candida lipase. The repeated esterification raised the AA content to 75% with a recovery of 71% of its initial content.
Chloramine T with iodine: A new reagent to determine the iodine value fo edible oils
Authors: Nagendrappa Giddappa , Urs S. Subramanya Raj , Rajalakshmi S. 
Published: May 2007

AbstractChloramine T (N‐chloro‐p‐toluenesulfonamide sodium salt) and iodine (2:1, w/w) in carbon tetrachloride and acetic acid (1:1, vol/vol), referred to as reagent (I) was found to be effective for the determination of Iodine value of edible oils. Reagent (I) reacted quantitatively with the double bonds of oils of known weight. The reagent left unreacted after 20–25 min was titrated against standard sodium thiosulfate solution (0.04 M) in presence of potassium iodide (10%, 5 mL). The difference in volume of sodium thiosulfate solution consumed by reagent (I) without and with oil was a basis to calculate the iodine value of oils used. The iodine values of different oils were also determined separately following the standard procedure of Wijs, and calculated iodine value was obtained from the gas chromatographic profile of fatty acids. The iodine value obtained by the new method was in agreement with the results of the standard methods. The results obtained indicate that the method could be a complementary or an alternative to the Wijs method.
Anomalous high iodine value of squalene and the impact on iodine values of shark liver oils
Authors: Ackman R. G. , Macpherson E. , Timmins A. 
Published: May 2007

AbstractSqualene has six ethylenic bonds, but the experimental iodine values in two different solvent systems—chloroform and cyclohexane/acetic acid—were 25% higher than the theoretical values. We propose that this results from an additional halogen adding at each of the two terminal ethylenic bonds carrying two methyl groups. In the solvent system of cyclohexane alone, the excess is only 3–4% greater than the theoretical. Mixtures of squalene in seal oil confirmed the additivity of the experimental squalene high iodine value and the seal oil fatty acid iodine value with reasonable accuracy but depended on the skill of the operator in obtaining the titration end point for cyclohexane/acetic acid. This observation has particular relevance for shark liver oils and olive oils.