Daniel Barrera-Arellano

Loss of tocopherols and formation of degradation compounds in triacylglycerol model systems heated at high temperature

Triolein, trilinolein and a mixture of both (1:1) were heated at 180 °C for 2, 4, 6, 8 and 10 h in the absence of tocopherols or in the presence of α-tocopherol (500 mg kg−1), δ-tocopherol (500 mg kg−1) or a mixture of α-, β-, γ- and δ-tocopherol (200–250 mg kg−1 each). Losses of tocopherols as well as increases in polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10 h heating. Results demonstrated that the antipolymerisation effect of tocopherols at high temperature depended on the degree of unsaturation affecting to a greater extent the less unsaturated substrate, triolein. The maximum effect for the three substrates was found when the tocopherol mixture was added. Interestingly, α-tocopherol losses were very rapid and independent of the unsaturation of the triacylglycerol system under the conditions used, although degradation of the substrate was significantly higher as the degree of unsaturation increased for any period of heating. © 1999 Society of Chemical Industry

Instantaneous characterization of vegetable oils via TAG and FFA profiles by easy ambient sonic-spray ionization mass spectrometry

A fast and reliable method is presented for the analysis of vegetable oils. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to efficiently desorb and ionize the main oil constituents from an inert surface under ambient conditions and to provide comprehensive triacylglyceride (TAG) and free fatty acid (FFA) profiles detected mainly as either [TAG + Na](+) or [FFA-H](-) ions. EASI(+/-)-MS analysis is simple, easily implemented, requires just a tiny droplet of the oil and is performed without any pre-separation or chemical manipulation. It also causes no fragmentation of TAG ions hence diacylglyceride (DAG) and monoacylglyceride (MAG) profiles and contents can also be measured. The EASI(+/-)-MS profiles of TAG and FFA permit authentication and quality control and can be used, for instance, to access levels of adulteration, acidity, oxidation or hydrolysis of vegetable oils in general.

Direct characterization of commercial lecithins by easy ambient sonic-spray ionization mass spectrometry

Commercial lecithins are composed mainly of phospholipids and triacylglycerols. The analysis of the commercial lecithins, including their fraction of phospholipids, normally involves laborious and expensive protocols. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to be an efficient technique for the analysis of lipids. Samples of commercial lecithins including standards, refined, deoiled and modified soy lecithin were tested. Characteristic profiles of phosphatidylcholines and triacylglycerols are detected by EASI(+)-MS, whereas EASI(-)-MS provided phosphatidylethanolamines, glycophospholipids and free fatty acids profiles. Acetylated lecithins also displayed characteristic acetylated derivatives. EASI-MS data was also compared to MALDI-MS, and found to display richer compositional information. The industrial process applied to lecithin fabrication was also characterised via typical EASI-MS profiles. EASI-MS both in its positive and negative ion modes offers a direct, fast and efficient technique able to characterise commercial lecithin.

Brazilian encapsulated fish oils: Oxidative stability and fatty acid composition

Encapsulated fish oils are extensively commercialized in Brazil. These products could have an effect in the reduction of heart diseases because of their high content of polyunsaturated fatty acids. However, information about their composition and quality are still lacking. Fatty acid composition, oxidative stability (Rancimat, 80°C, 2.5 g sample and 8.3 L/h air), peroxide value (PV), and polar compound content were determined in sixteen trademarked encapsulated fish and cod-liver oils, purchased from Brazilian markets. The highly polyunsaturated fatty acid (eicosapentaenoic acid+docosahexaenoic acid) level appear to be typical of marine oils (16.2 and 32.1%). The PV ranged from 2.1 to 20.3 meq/kg, which is considered high, whereas the Rancimat induction periods varied from 1.95 to 8.45 h. The samples analyzed contained from 0.1 to 8.3% polar components. In some cases, both composition and quality were inadequate for this kind of product. One of the samples did not contain cod-liver oil, it appears that it contained soybean oil.

Production and characterization of lipid microparticles produced by spray cooling encapsulating a low molar mass hydrophilic compound

O objetivo deste trabalho foi produzir e caracterizar particulas lipidicas (MpLs) que possam ser utilizadas como carreadores de altas quantidades de um recheio hidrofilico e avaliar a influencia da quantidade de recheio sobre a performance das microparticulas. As MpLs foram produzidas por spray cooling a partir de misturas de acidos graxos liquidos e solidos (acido estearico e oleico) e gordura vegetal hidrogenada, contendo solucao de glucose como recheio e lecitina de soja como surfactante. A performance das MpLs foi avaliada por meio da quantificacao do recheio efetivamente encapsulado, da quantidade presente na superficie das MpLs e do perfil de liberacao do recheio em meio aquoso. Observacoes morfologicas mostraram que as MpLs apresentaram forma esferica e superficie enrugada porem continua, com um tamanho medio entre 25 e 32 µm. A quantidade efetivamente encapsulada foi superior a 78% para todas as formulacoes avaliadas. Maior quantidade de glucose superficial foi observada nas formulacoes em que solucoes mais concentradas de glucose foram utilizadas, independente da relacao lipidio-solucao. Os resultados da liberacao mostraram que a retencao do recheio foi significativamente influenciada pela concentracao de glucose utilizada, enquanto a modulacao da liberacao foi influenciada pela relacao lipidio:solucao de glucose.

Rapid fingerprinting of sterols and related compounds in vegetable and animal oils and phytosterol enriched- margarines by transmission mode direct analysis in real time mass spectrometry.

Plant-derived sterols, often referred to as phytosterols, are important constituents of plant membranes where they assist in maintaining phospholipid bilayer stability. Consumption of phytosterols has been suggested to positively affect human health by reducing cholesterol levels in blood via inhibition of its absorption in the small intestine, thus protecting against heart attack and stroke. Sterols are challenging analytes for mass spectrometry, since their low polarity makes them difficult to ionize by both electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI), typically requiring derivatization steps to overcome their low ionization efficiencies. We present a fast and reliable method to characterize the composition of phytosterols in vegetable oils and enriched margarines. The method requires no derivatization steps or sample extraction procedures thanks to the use of transmission mode direct analysis in real time mass spectrometry (TM-DART-MS).

Quantitation of triacylglycerols in vegetable oils and fats by easy ambient sonic-spray ionization mass spectrometry

This innovative mass spectrometric technique provides simple, quick, and reliable quantitative analysis of triacylglycerols in vegetable oils and fats. The easy ambient sonic-spray ionization mass spectrometry (EASI-MS) technique provides simple, quick, and reliable qualitative analysis of triacylglycerols (TAG) in vegetable oils. The use of this ambient mass spectrometry technique, which does not require separation or derivatization before analysis, for precise quantitative analyses has yet to be demonstrated. In this study, the TAG composition of edible vegetable oils, hydrogenated vegetable oils and cocoa butter was quantitated by EASI-MS. The results were compared with those obtained by theoretical predictions of the TAG composition performed by a software projection, which uses a mathematical algorithm of distribution of the fatty acids (FA) in the TAG molecule, and by the direct gas chromatography method (GC-FID). Acceptable correlation coefficients were observed between the three methods during the analysis of vegetable oils and hydrogenated vegetable oils. EASI-MS offers not only simplicity, speed and selectivity for oil analysis but also precise quantitation of the TAG composition. Therefore, EASI-MS is a promising substitute for the more demanding and time-consuming standard protocols, which require separation and sometimes derivatization before analysis.

Chemical Characterization of Major and Minor Compounds of Nut Oils: Almond, Hazelnut, and Pecan Nut

The aim of this work was to characterize the major and minor compounds of laboratory-extracted and commercial oils from sweet almond, hazelnut, and pecan nut. Oils from sweet almond, hazelnut, and pecan nut were obtained by means of an expeller system, while the corresponding commercial oils were provided from Vital Âtman (BR). The contents of triacylglycerols, fatty acids, aliphatic and terpenic alcohols, desmethyl-, methyl-, and dimethylsterols, squalene, and tocopherols were determined. Oleic, palmitic, and linoleic acids were the main fatty acids. Desmethylsterols were the principal minor compounds with β-sitosterol being the most abundant component. Low amounts of aliphatic and terpenic alcohols were also found. The major tocopherol in hazelnut and sweet almond oils was α-tocopherol, whereas γ-tocopherol prevailed in pecan nut oil. Principal component analysis made it possible for us to differentiate among samples, as well as to distinguish between commercial and laboratory-extracted oils. Heatmap highlighted the main variables featuring each sample. Globally, these results have brought a new approach on nut oil characterization.

TAG, DAG and FFA profiles of dry-cured ham by easy ambient sonic-spray ionization mass spectrometry after thermal imprinting

Espectrometria de massas ambiente com ionizacao por sonic-spray (EASI-MS), uma tecnica de espectrometria de massas ambiente recem desenvolvida, foi diretamente utilizada para a obtencao do perfil de triacilglicerois (TAG), diacilglicerois (DAG) e acidos graxos livres (FFA) em diferentes tipos de presuntos crus curados, apos impressao termica. A tecnica e simples, rapida e confiavel, alem de nao requerer nenhum tipo de hidrolise, derivatizacao ou separacao cromatografica, o que representa vantagens sobre outros procedimentos analiticos normalmente utilizados para este proposito. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS), a recently developed ambient mass spectrometry technique, was used for the direct analysis of triacylglycerols (TAG), diacylglycerols (DAG) and free fatty acids (FFA) in different types of dry-cured ham, after thermal imprinting. The technique is simple, fast and reliable, not requiring hydrolysis, derivatization or chromatographic separation, which represents advantages over other analytical procedures usually used for this purpose.

Desorption/ionization efficiencies of triacylglycerols and phospholipids via EASI-MS

Knowledge of the major effects governing desorption/ionization efficiency is required for the development and application of ambient mass spectrometry. Although all triacylglycerols (TAG) have the same favorable protonation and cationization sites, their desorption/ionization efficiencies can vary dramatically during easy ambient sonic-spray ionization because of structural differences in the carbon chain. To quantify this somewhat surprising and drastic effect, we have performed a systematic investigation of desorption/ionization efficiencies as a function of unsaturation and length for TAG as well as for diacylglycerols, monoacylglycerols and several phospholipids (PL). Affinities for Na(+) as a function of unsaturation level have also been assayed via comprehensive metadynamics calculations to understand the influence of this phenomenon on the ionization efficiency. The results suggest that dipole-dipole interactions within a carbon chain tuned by unsaturation sites govern ionization efficiency of TAG and PL.