Synthesis of structured triglycerides from peanut oil with immobilized lipase

Structured triglycerides (ST) that contain medium- and long-chain fatty acids were synthesized by lipase-catalyzed interesterification between tricaprylin and peanut oil. To select appropriate enzymes, we investigated nine commercial lipase preparations for their ability to hydrolyze pure triglycerides as well as natural oils. Three microbial lipases from Rhizomucor miehei (RML), Candida sp. (CSL), and Chromobacterium viscosum (CVL) gave good results, and immobilized preparations were used in the interesterification. RML gave the highest yields of ST (73%, 40°C), although its hydrolytic activity toward triolein was low. As the temperature was raised to 50°C, the yield of ST increased to 79%. After 120 h reaction time, remaining activities were high for CSL (71%), moderate for CVL (48%), and low for RML (20%). Parts of this paper were presented as a poster at the Biochemical Engineering Conference IX, May 1995, Davos, Switzerland.     

Characterization of triacylglycerols in madeira laurel oil by HPLC-atmospheric pressure chemical ionization-MS

Madeira laurel oil was fractionated by liquid extraction combined with TLC, and TAGs were analyzed by HPLC coupled with atmospheric pressure chemical ionization-MS (APCI-MS). Eluted molecular species compositions of the eluted TAG in the complex natural mixture were determined by GC identification of FAME and byLC-atmospheric pressure chemical ionization (APCI)-MS analysis of the lipid. The APCI-MS spectra of most TAG exhibited [M+H]⁺ and [M−RCOO]⁺ ions, which defined the M.W. and the molecular association of fatty acyl residues, respectively. Despite the relatively high degree of saturation, with a saturated/unsaturated ratio of 0.70, no totally saturated TAG nor mixed asymmetric TAG with two saturated FA (SSM or SSU, where S is saturated, M is monounsaturated, and U is unsaturated) were found. This type of molecular structure provides a possible explanation for the relatively low m.p. (12–15°C) and also the high oxidative resistance observed.     

Enzyme-assisted aqueous extraction of peanut oil

Enzyme-assisted aqueous extraction of oil from oilseeds is a relatively recent technique. In the present study, peanut oil was extracted under optimized aqueous extraction conditions using Protizyme^™, which is predominantly a mixture of acid, neutral, and alkaline proteases. The optimal conditions were: enzyme concentration of 2.5% (w/w) in 10 g of peanut seeds, pH 4.0, 40°C, and 18 h incubation with constant shaking at 80 rpm. Centrifuging the mixture at 18,000 × g for 20 min separated the oil with a recovery of 86–92%. The merits of this process over existing solvent extraction and/or mechanical pressing methods are discussed.     

Method for analysis of TAG formed by reaction of fish oil with hydrogenated soybean oil

An HPLC method was developed for analysis of the TAG formed during interesterification of a fish oil rich in DHA residues and of a fully hydrogenated soybean oil. TAG species were separated using a three-phase (acetone/acetonitrile/chloroform) solvent system. Peak identities were assigned on the basis of a multiple linear regression analysis by using factors such as carbon number, number of double bonds, and number of PUFA in the molecule as predictors for TAG retention time. Good agreement between experimental and predicted retention times was observed when the effect of the PUFA was separated in the regression model from that of the monounsaturated FA. In addition, the new method permits one to determine tristearin at concentrations up to 3 mg/mL without encountering the problem of partial retention of this TAG in the column that was observed when chloroform is not incorporated in the mobile phase.     

Retarding autoxidation in raw peanut oil by addition of water

Addition of water at levels of 0.25 to 1.00% (wt/vol) to raw peanut oil inhibited the formation of peroxides in the oil. The free fatty acid content of oils to which water had been added also did not increase appreciably compared to a control oil. To improve the stability of the oil, a moisture content of 0.2%, which is about ten times higher than the Brunauer-Emmett-Teller monomolecular moisture content of the oil, has been suggested.     

Characterization of olive oil classes using a Chemsensor and pattern recognition techniques

Classification is an important component of food quality assurance, as methods to guarantee authenticity of food products are widely demanded by food producers, processors, consumers, and regulatory bodies. The objective of this work was to develop a rapid classification method in order to discriminate virgin olive oil, olive oil, and „orujo” olive oil, the prices of which differ dramatically in the market on a ccount of the high quality level of the former. For these purposes, new ChemSensor equipment that combines a headspace autosampler with a mass-selective detector and Pirouette data evaluation software was used. To take into account the large number of samples analyzed (50 samples repeated 10 times), as well as the wide interval of m/z ratios scanned (41–170), chemometric approaches were necessary. Cluster analysis, principal component analysis, K-nearest neighbors, and soft independent modeling of class analogy (SIMCA) were applied to model the different oil classes. The results indicated good classification and prediction abilities, with SIMCA affording the best results (viz. 97% specificity).     

Stereospecific analysis of TAG from sunflower seed oil

Stereospecific analysis of TAG from a sunflower seed oil of Tunisian origin was performed. The TAG were first fractionated according to chain length and degree of unsaturation by RP-HPLC. The four major diacid- and triacid-TAG fractions were palmitoyldilinoleoyl-glycerol, dioleoyllinoleoylglycerol, oleoyldilinoleoylglycerol, and palmitoyloleoyl-linoleoyl-glycerol, amounting to 7.2, 16.6, 29.5, and 12 mol%, respectively. The TAG of the four fractions were individually submitted to stereospecific analysis, using a Grignard-based partial deacylation, separation of sn-1,2(2,3)-DAG from sn-1,3-DAG by boric acid-impregnated silica gel TLC plates, conversion of the sn-1,2(2,3)-DAG to their 3,5-dinitrophenylurethane (DNPU) derivatives, fractionation of DNPU derivatives by RP-HPLC, resolution of the DNPU-DAG by HPLC on a chiral column, transmethylation of each sn-DNPU-DAG fraction, and analysis of the resulting FAME by GC. The data obtained were used to determine the triacyl-sn-glycerol composition of the main TAG of the oil. Fifteen triacyl-sn-glycerols were identified and quantified, representing, along with the monoacid-TAG, trilinoleoylglycerol and trioleoylglycerol, more than 90% of the total oil TAG. The two major triacyl-sn-glycerols were trilinoleoyl-glycerol and 1-linoleoyl-2-linoleoyl-3-oleoyl-glycerol (18.6 and 18.5% of the total, respectively). Results clearly identified linoleic acid as the major FA at the sn-2 position, whereas oleic and palmitic acids were the major FA at the sn-3 position. The sn-1 position was occupied to nearly the same extent by linoleic and oleic acids, and to a greater extent by palmitic acid, which was practically absent at the sn-2 position.     

Antioxidant constituents of peanut oil

The components responsible for increased stability of raw peanut oil at a high relative humidity (RH) of 91% were examined in peanut oil and methyl linoleate systems. Of the constituents, the native gums, which were mostly phospholipids and glycolipids, showed increased antioxidant activity at 91% RH. The isolated components of the gums, namely phospholipids and glycolipids, were prooxidant individually or in combination. Tocopherols did not show increased antioxidant activity at 91% RH.     

Enrichment of phospholipids from neutral lipids in peanut oil by high-performance liquid chromatography

Phospholipids from crude peanut oil were enriched on a 2-cm silica column and subsequently separated from neutral lipids within the chromatographic system without prior concentration. Hexane effectively removed the bulk neutral lipids, leaving the adsorbed phospholipids on the silica precolumn. Individual phospholipids were separated from the remaining neutral lipids and from each other by using two mixed solvents and a gradient program. This method separates the phospholipids in approximately 27 min after the desired enrichment level has been reached. The research reported in this paper was a cooperative effort by the Agricultural Research Service of the United States Department of Agriculture and the North Carolina Agricultural Research Service, Raleigh, NC 27695-7625.     

Rapid MS method for analysis of cocoa butter TAG

Ammonia negative ion CI-MS was applied to analyze the M.W. distribution and regioisomeric structure of TAG in cocoa butter and in cocoa butter equivalents. The M.W. distribution results obtained for a reference cocoa butter were consistent with corresponding results obtained in an intercomparison study by chromatographic methods. Minor but statistically significant differences were observed when proportions of the three major M.W. species (52∶1, 54∶1, and 50∶1; acyl carbon number/number of double bonds) in a mixture of nine cocoa butters and in mixtures containing 10 or 20% (w/w) of specific cocoa butter equivalents were compared. Tandem MS was used to determine the regioisomeric structure of the three major TAG M.W. species in cocoa butter and in cocoa butter equivalents. The regioisomeric structure in cocoa butter and in all the equivalents analyzed were nearly identical, oleic acid being located primarily in the sn-2 position. These results cannot be exploited in detecting added foreign fats in this case. However, the present study shows that useful TAG composition data, which may be used to detect foreign fats in cocoa butter by applying chemometric data evaluation, can be obtained by MS in a significantly shorter time compared to chromatographic methods.     

LCMS-MS法检测小麦粉中12种农药的残留

[目的]建立吡蚜酮、氧乐果、敌百虫、啶虫脒、乐果、甲磺隆、氯磺隆、多效唑、嘧菌环胺、烯唑醇、喹硫磷、甲氨基阿维菌素苯甲酸盐12种农药在小麦中的液相色谱-三重串联质谱同时检测和确证方法.[方法]小麦样品经粉碎后,0.1％(体积分数)冰醋酸-乙腈提取,NH2氨基柱填料和石墨化炭黑固相分散净化,含0.1％甲酸的乙腈水混合液定容过微孔滤膜后用液相色谱串联四级杆质谱联用仪LC-MS-MS检测和确证.[结果]方法在10～1000μg/L范围内保持良好的线性关系,相关系数大于0.99.12种农药在10、50、100 tg/kg添加水平的回收率和相对标准偏差的数据表明:12种农药的回收率均为72％～107％,RSD为1.5％～13.3％,回收率和相对标准偏差达到相应标准的要求.[结论]该方法快速、灵敏、适用广泛、操作简便及污染小,适用于小麦籽粒中农药残留的定性定量分析.     

Comprehensive Triacylglycerol Characterization of Oils and Butters of 15 Amazonian Oleaginous Species by ESI‐HRMS/MS and Comparison with Common Edible Oils and Fats

The Amazon rain forest encompasses an extraordinary source of vegetable oils with many applications, especially for food, pharmaceutical and cosmetics industries. In this work, the main composition of fifteen Amazonian oils and butters are investigated via gas chromatography‐mass spectrometry (GC‐MS) and electrospray ionization high resolution mass spectrometry (ESI‐HRMS). Triacylglycerols (TAG) are characterized by their fragmentation spectra and comparison with the LIPID MAPS database, resulting in a detailed compendium of TAG composition of these samples. Over 70 different TAG are putatively annotated per sample and the occurrence of isomers is remarkable, showing that TAG complexity in these samples is considerably higher than ever reported. The TAG composition of the Amazonian samples are also statistically evaluated using principal component analysis (PCA) for comparison to common edible oils such as soybean, corn, coconut, and olive oil. Some tendencies of grouping are observed: butters with medium chain fatty acids (FA); butters with high oleic FA; and oils with high oleic and high linoleic FA contents. This study provided profiles that ensure Amazonian oils and butters authenticity, quality and also aids in understanding their properties and the best applications for each. Practical Applications: It is expected that this comprehensive set of data on the TAG composition of Amazonian oils and butters will help guide the use and applications of these products, providing consumers with the best benefits from a nutritional perspective. Moreover, adulterations could be more easily detected when a database is available, since the chemical composition of certified samples is investigated in this work. Ultimately, this study can encourage the sustainable production and applications of Amazonian oils and appropriate use of Amazon rain forest resources.     

Mass spectrometric characterization ofVernonia galamensis oil

Vernonia galamensis seed oil is a natural source of epoxidized triacylglycerols, which consist of 52% trivernolin and a mixture of other triacylglycerols. Epoxidized oils are used for industrial applications, such as coatings and plastic formulations. To determine the major molecular species present in Vernonia oil, desorption chemical ionization/mass spectrometry and mass spectrometry/mass spectrometry were used to determine its glyceride composition. Seven triacylglycerols predominated: divernoloylarachidonate, trivernolin, divernoloylstearate, divernoloyloleate, divernoloyllinoleate, dilinolenoyl vernolate and divernoloylpalmitate.     

Study on the aluminium chloride-modification for heavy fraction of light diesel oil using tandem mass spectrometry

Tandem mass spectrometry was used to follow the low temperature catalytic modification of the diesel oil heavy fraction in the presence of aluminium chloride. The molecular distribution from chemical ionization mass spectroscopy (c.i.m.s.) of raw feedstock ranges from 150 to 250, with an average molecular weight of 219 (v.p.o.). That of the finally modified pitch ranges from 200 to 800, mainly concentrated between 200 and 500 with v.p.o. molecular weight of 452. The m.s.-m.s. fragmentation analysis of three dominant, characteristic protonated parent ions m/z 207, 373, 385, showed ethyl phenanthrenes (-anthracenes), dimers from phenanthrene (anthracene) and C₁-phenanthrene with substantial naphthenic groups, dimers from C₁-phenanthrenes and copolymers from hexahydropyrene with phenanthrene, chrysene with C₂-naphthalene, etc., respectively, to be the main structural types of these parent mass numbers. This modified pitch material, with a characteristic low degree of condensation and extensive naphthenic structures proved to be suitable for transformation into mesophase pitch with high fluidity and a large domain-type anisotropic texture.     

The role of comprehensive chromatography in the characterization of edible oils and fats

Chromatography has a very long history in the analysis of edible oils and fats. Hyphenations of two chromatographic methods, or couplings of a chromatographic separation technique with spectroscopic detection and identification devices, are used if the resolving power of the technique needs to be improved. More recently, the analytical benefits of comprehensive two‐dimensional (2D) chromatography, in its various operational modes, have been exploited by the oil and fat chromatographic community. In comprehensive 2D chromatography, the entire sample injected is subjected to two independent separation processes. In the present contribution, the principles of comprehensive 2D chromatography are briefly discussed. Next, the advantages of comprehensive separations for lipid analysis are illustrated using the concept of generic chromatographic applications. This concept distinguishes three generic reasons to apply chromatographic separations: target compound analysis, group‐type separation, and chromatographic fingerprinting. Examples of how comprehensive multi‐dimensional methods were successfully applied to solve problems in the edible oils and fats area are given. We believe that these multi‐dimensional techniques truly add new dimensions to oil and fat analysis, providing researchers in the area with novel tools for unraveling edible oil or fat samples with their complex compositions.     

Determination of molecular species of oil triacylglycerols by reversed-phase and chiral-phase high-performance liquid chromatography

A method is described for the determination of molecular species of oil triacylglycerols. The method is based on the analytical separation of the enantiomericsn-1,2-andsn-2,3-diacylglycerols, derived from triacylglycerols, by high-performance liquid-chromatography (HPLC) on a chiral column containing N-(R)-1-(α-naphthyl)ethylaminocarbonyl-(S)-valinecarbonyl-(S)-valine as stationary phase. Model triacyl-glycerol molecules comprising three known fatty acids were isolated from peanut oil and cottonseed oil by a combination of argentation-TLC and reversed-phase HPLC and submitted to partial chemical deacylation. The derivedsn-1,2(2,3)-diacylglycerols were analyzed and fractionated as 3,5-dinitrophenyl urethane derivatives by reversed-phase HPLC according to chainlength and unsaturation. From thesn-1,2(2,3)-diacylglycerol composition and the diacylglycerolsn-1,2-andsn-2,3-enantiomer composition, the individual molecular species of four peanut oil triacylglycerols and one cottonseed oil triacylglycerol were identified and quantitated. The method can be applied to triacylglycerols of any other oil or fat.     

LC-electrospray ionization and LC-FABMS study of flavonoid glycosides extracted from peanut meal

HPLC, HPLC-electrospray ionization (LC-ESI), and LC-FABMS were used to characterize flavonoid glycosides in the methanol extract from peanut meal. Five isoflavones, diadzin, glycitin, genistin, daidzein, and genistein, were separated by HPLC and characterized by comparison with known standards using ESI-MS. The flavonoid methylquercetin (rhamnetin) was present in the methanol extract from peanuts and identified by ESI-MS. Four other flavonoids, two quercetin diglycosides, one quercetin monoglucoside, and isorhamnetin glucoside, were found to be present in the methanol extract based on their reversed-phase elution pattern, mass ions, and fragment ions using flow-FABMS.     

Quality control of camellia oil based on HPLC fingerprinting techniques combined with chemometric methods for triglycerides

Triglycerides (TAGs) play an important role in the physiological function of vegetable oils. Camellia oil has a variety of good physiological functions. Therefore, a qualitative and quantitative method for the determination of TAGs in camellia oil by high-performance liquid chromatography-diode array detector/electro spray ionization mass spectrometry was developed. The 16 TAGs that separated were identified and quantified by peak-area normalization. In addition, the major TAGs in camellia oil were OOO (25.25%), OLO (20.72%), POL (9.23%), OLL (8.22%), and OOP (8.22%). Moreover, the content of oleic acid in camellia oil was 81.74%. Using fingerprint techniques, 15 common peaks in 12 samples were selected as characteristic peaks to evaluate the differences in the composition of camellia oil samples. In addition, the samples were further classified by chemometric methods. It is shown that the camellia oil samples with high similarity from two cities in the main producing areas of Zhejiang province could be further classified according to the planting areas by the combination of chromatographic fingerprints and chemometric methods.     

Fractionation of the triacylglycerols of lipase-modified butter oil

Triacylglycerols (TGs) of lipase-modified butter oil were separated into saturated, monoene, diene and triene fractions on ap-propylbenzene sulfonic acid solid-phase extraction column loaded with silver ions. Fatty acid analysis of the fractions showed that the amounts of saturated TGs (98.4 mol%) and monoene TGs (26.0 mol%) in the saturated and monoene fractions, respectively, were close to the theoretical amounts of TGs in pure fractions. The column method provides a useful alternative to AgNO₃-thin-layer chromatography as a means of separating the TGs of butterfat and producing relatively pure TG fractions for further analysis by gas chromatography (GC) or GC-mass spectrometry.