Stereospecific distribution of fatty acids in triacylglycerols of olive oils

Metabolomic Investigation of Brain and Liver in Rats Fed Docosahexaenoic Acid in Regio- and Enantiopure Triacylglycerols

SCOPE

N-3 polyunsaturated fatty acids (n-3 PUFAs) play important roles in cognitive functions. However, there is a lack of knowledge on the metabolic impact of regio- and stereo-specific positioning of n-3 PUFAs in dietary triacylglycerols.

METHODS AND RESULTS

Rats in a state of mild n-3 PUFA deficiency are fed daily with 360 mg triacylglycerols containing DHA (docosahexaenoic acid) at sn (stereospecific numbering)-1, 2, or 3 positions and 18:0 at remaining positions, or an equal amount of tristearin for 5 days. Groups fed with n-3 deficient diet and normal n-3 adequate diet are included as controls. The metabolic profiles of the brain and liver are studied using NMR (nuclear magnetic resonance)-based metabolomics. Several metabolites of significance in membrane integrity and neurotransmission, and glutamate, in particular, are significantly lower in the brain of the groups fed with sn-1 and sn-3 DHA compared to the sn-2 DHA group. Further, the tristearin and DHA groups show a lower lactate level compared to the groups fed on normal or n-3 deficient diet, suggesting a prominent role of C18:0 in regulating energy metabolism.

CONCLUSION

This study sheds light on the impact of stereospecific positioning of DHA in triacylglycerols and the role of dietary stearic acid on metabolism in the brain and liver.

Geographical authentication of virgin olive oil by GC-MS sesquiterpene hydrocarbon fingerprint: Verifying EU and single country label-declaration

According to the last report from the European Union (EU) Food Fraud Network, olive oil tops the list of the most notified products. Current EU regulation states geographical origin as mandatory for virgin olive oils, even though an official analytical method is still lacking. Verifying the compliance of label-declared EU oils should be addressed with the highest priority level. Hence, the present work tackles this issue by developing a classification model (PLS-DA) based on the sesquiterpene hydrocarbon fingerprint of 400 samples obtained by HS-SPME-GC-MS to discriminate between EU and non-EU olive oils, obtaining an 89.6% of correct classification for the external validation (three iterations), with a sensitivity of 0.81 and a specificity of 0.95. Subsequently, multi-class discrimination models for EU and non-EU countries were developed and externally validated (with three different validation sets) with successful results (average of 92.2% of correct classification for EU and 96.0% for non-EU countries).

Novel Strategy for the Recognition of Adulterant Vegetable Oils in Essential Oils Commonly Used in Food Industries by Applying 13C NMR Spectroscopy

Essential oils (EOs) are valuable products commonly employed in the food industry and intensively studied as biopreservatives for the extension of food shelf-life. Unfortunately, EOs might be counterfeit to increase industrial profits. Among the possible adulterants, vegetable oils (VOs) must be considered for their characteristics and low costs. We aimed to apply nuclear magnetic resonance (NMR) spectroscopy for the detection and identification of VOs in mixtures with EOs. This innovative strategy is based on comparing the peak area ratio matrices of characteristic VO ¹³C NMR fatty acid signals with those of adulterated EOs. The identification of the VOs was achieved by calculating the matrix similarity at different confidence levels. The strategy demonstrated the capacity to efficiently recognize the presence of adulteration and the type of VO adulterant in mixtures. Thus, the method was applied to 20 commercial EOs, and VOs were detected and then identified in four samples.

Eleven Monovarietal Extra Virgin Olive Oils from Olives Grown and Processed under the Same Conditions: Effect of the Cultivar on the Chemical Composition and Sensory Traits

Eleven Italian monovarietal extra virgin olive oils (MEVOOs) (Carboncella, Coratina, Frantoio, Leccino, Marzio, Maurino, Moraiolo, Piantone di Falerone, Pendolino, Rosciola, Sargano di Fermo) from olives grown in the same experimental olive orchard, under the same conditions (fertilization, irrigation), and processed with the same technology (three-way continuous plant) were investigated. As a result, the impact of the olive cultivar on fatty acid and triacylglycerols composition, oxidative stability, polar phenolic profile and sensory properties (panel test) of the oil was assessed. Pendolino, Maurino and Marzio oils presented the highest levels (p < 0.01) of palmitic, linoleic and linolenic acids % and the lowest oleic:linoleic ratio. Within triacylglycerols, triolein (OOO) strongly varied among the oils, with Coratina and Leccino having the highest content. Frantoio showed the lowest 1-Stearoyl-2-palmitoyl-3-oleylglycerol and 1,3-Distearoyl-2-oleylglycerol amounts. Rosciola showed the highest level (p < 0.01) for two of the most abundant secoiridoid derivatives (the dialdehydic forms of decarboxymethyl elenolic acid linked to hydroxytyrosol and tyrosol). A good correlation was found between total phenolic content and oxidative stability, indicating Marzio and Leccino respectively as the richest and poorest genotypes. Sensory variability among varieties was mainly linked to perceived bitterness, pungency and fruitiness, while no effects were found on secondary flavors.

Synthesis and enantiospecific analysis of enantiostructured triacylglycerols containing n-3 polyunsaturated fatty acids

The stereospecific structure of triacylglycerols (TAGs) affects the bioavailability of fatty acids. Lack of enantiopure reference compounds and effective enantiospecific methods have hindered the stereospecific analysis of individual TAGs. Twelve novel enantiostructured AAB-type TAGs were synthesized containing one of the three n-3 polyunsaturated fatty acid: α-linolenic acid (ALA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) in sn-1 or sn-3 position. These compounds formed six enantiomer pairs, which were separated with recycling high-performance liquid chromatography using chiral columns and UV detection. The chromatographic retention behavior of the enantiomers and the stereospecific elution order were studied. The enantiomer with an n-3 PUFA in the sn-1 position eluted faster than the enantiomer with the n-3 PUFA in the sn-3 position, regardless of the carbon chain length and number of double bonds of the PUFA. TAG enantiomers containing DHA exhibited highly different retention on the chiral column and were separated after the first column, whereas recycling was needed to separate the enantiomer pairs containing ALA or EPA. The system using two identical columns and one mobile phase, without sample derivatization, proved to be very effective also for peak purity assessment, confirming the enantiopurity of the synthesized structured TAGs being higher than 98 % (96 % ee).

Direct flow injection profiling of acyl glycerols from food products using isopropanol as solvent

This work proposes a novel method for the direct flow injection profiling of acylglycerols in edible oils and fats without preliminary extraction and consequent reconstitution in the injection solvent. The work exploits the outstanding performance of high-resolution mass spectrometry to target unique elemental compositions even in the most complex matrices. The performance of isopropanol as the unique solvent for both the solubilization and analysis of acylglycerols was investigated in comparison with other classical methods involving preliminary extractions, sample recovery, and analysis. The calibrations of two triglyceride standards (triolein and trilinolenin) were successfully performed in presence and absence of oil matrix. As final application, the effects on the acylglycerol fraction of a heat treatment on three different fat samples (extra virgin olive oil, lard oil, and fat from dry cured ham-speck) were monitored. The proposed method is therefore suitable for a rapid evaluation of acylglycerol fractions in food lipid samples.

Palm oil and cardiovascular disease: a randomized trial of the effects of hybrid palm oil supplementation on human plasma lipid patterns

This study examines, for the first time, the effect of hybrid Elaeis oleifera × E. guineensis palm oil supplementation on human plasma lipids related to CVD risk factors. One hundred sixty eligible participants were randomized and assigned to one of the two treatments: 25 mL hybrid palm oil (HPO group) or 25 mL extra virgin olive oil (EVOO group) daily for 3 months. Fasting venous samples were obtained at baseline and after 1, 2 and 3 months for measurement of plasma lipids (TC, LDL-C, HDL-C and TAGs). Changes in body mass index and waist circumference were also assessed. Although there was an overall reduction in TC (7.4%, p < 0.001) and in LDL-C (15.6%, p < 0.001), no significant differences were found between the treatment groups in a repeated measures analysis of variance for TC (p = 0.0525), LDL-C (p = 0.2356), HDL-C (p = 0.8293) or TAGs (p = 0.3749). Furthermore, HPO consumption had similar effects on plasma lipids to EVOO, thus providing additional support for the concept that hybrid Elaeis oleifera × E. guineensis palm oil can be seen as a "tropical equivalent of olive oil".

Lipidomics applications in health, disease and nutrition research

The structural and functional diversity of lipids accounts for their involvement into a wide range of homeostatic processes and disease states, including lifestyle-related diseases as well as genetic conditions. Challenges presented by this diversity have been addressed to a great extent by the development of lipidomics, a platform that makes possible the detailed profiling and characterisation of lipid species present in any cell, organelle, tissue or body fluid, and allows for a wider appreciation of the biological role of lipid networks. Progress in the field of lipidomics has been greatly facilitated by recent advances in MS and includes a range of analytical platforms supporting applications spanning from qualitative and quantitative assessment of multiple species to lipid imaging. Here we review these MS techniques currently in routine use in lipidomics, alongside with new ones that have started making an impact in the field. Recent applications in health, disease and nutrition-related questions will also be discussed with a view to convey the importance of lipidomics contributions to biosciences and food technology.

Ultrahigh resolution mass spectrometry and accurate mass measurements for high-throughput food lipids profiling

In the present study, accurate mass measurements by ultrahigh resolution mass spectrometry with Orbitrap-Exactive working at resolving power R: 100,000 (m/z 200, full width at half maximum) with an accuracy better than 2 ppm in all the mass range (m/z 200 to 2000) were used to show a detailed molecular composition of diverse edible oils and fats. Flow injection was used to introduce samples into the mass spectrometer, obtaining a complete analysis of each sample in less than 10 min, including blanks. Meticulous choice of organic solvents and optimization of the ion source and Orbitrap mass analyzer parameters were carried out, in order to achieve reproducible mass spectra giving reliable elemental compositions of the lipid samples and to prevent carry over. More than 200 elemental compositions attributable to diacylglycerols, triacylglycerols (TAGs), and their oxidation products have been found in the spectra of food lipids from different origin. Several compounds with very close molecular mass could only be resolved through ultrahigh resolution, allowing detailed and robust TAG profiling with a high characterization potential.

The significance of different diacylgycerol synthesis pathways on plant oil composition and bioengineering

The unique properties of vegetable oils from different plants utilized for food, industrial feedstocks, and fuel is dependent on the fatty acid (FA) composition of triacylglycerol (TAG). Plants can use two main pathways to produce diacylglycerol (DAG), the immediate precursor molecule to TAG synthesis: (1) De novo DAG synthesis, and (2) conversion of the membrane lipid phosphatidylcholine (PC) to DAG. The FA esterified to PC are also the substrate for FA modification (e.g., desaturation, hydroxylation, etc.), such that the FA composition of PC-derived DAG can be substantially different than that of de novo DAG. Since DAG provides two of the three FA in TAG, the relative flux of TAG synthesis from de novo DAG or PC-derived DAG can greatly affect the final oil FA composition. Here we review how the fluxes through these two alternate pathways of DAG/TAG synthesis are determined and present evidence that suggests which pathway is utilized in different plants. Additionally, we present examples of how the endogenous DAG synthesis pathway in a transgenic host plant can produce bottlenecks for engineering of plant oil FA composition, and discuss alternative strategies to overcome these bottlenecks to produce crop plants with designer vegetable oil compositions.

Review: multistage mass spectrometry in quality, safety and origin of foods

Quality and safety control and the validation of origin are hot issues in the production of food and its distribution, and are of primary concern to food and agriculture organization. Modern mass spectrometry (MS) provides unique, reliable and affordable methodologies to approach with a high degree of scientificity any problem which may be posed in this field. In this review the contribution of mass spectrometry to food analysis is presented aiming at providing clues on the fundamental role of the basic principles of gas-phase ion chemistry in applied research fields. Applications in proteomics, allergonomics, glycomics, metabolomics, lipidomics, food safety and traceability have been surveyed. The high level of specificity and sensitivity of the MS approach allows the characterization of food components and contaminants present at ultra-trace levels, providing a distinctive and safe validation of the products.

Comparison among different gilthead sea bream (Sparus aurata) farming systems: activity of intestinal and hepatic enzymes and 13C-NMR analysis of lipids

In order to evaluate differences in general health and nutritional values of gilthead sea bream (Sparus aurata), the effects of semi-intensive, land-based tanks and sea-cages intensive rearing systems were investigated, and results compared with captured wild fish. The physiological state was determined by measuring the activity of three different intestinal digestive enzymes: alkaline phosphatase (ALP), leucine aminopeptidase (LAP) and maltase; and the activity of the hepatic ALP. Also, the hepatic content in protein, cholesterol, and lipid were assessed. ¹³C-NMR analysis for qualitative and quantitative characterization of the lipid fraction extracted from fish muscles for semi-intensive and land based tanks intensive systems was performed. The lipid fraction composition showed small but significant differences in the monounsaturated/saturated fatty acid ratio, with the semi-intensive characterized by higher monounsaturated and lower saturated fatty acid content with respect to land based tanks intensive rearing system.

Effect of latitude and weather conditions on the regioisomer compositions of alpha- and gamma-linolenoyldilinoleoylglycerol in currant seed oils

The regioisomer compositions of triacylglycerols (TAG) 18:3(n-3)/18:2(n-6)/18:2(n-6) (Ala/L/L) and 18:3(n-6)/18:2(n-6)/18:2(n-6) (Gla/L/L) in seed oils of black and green currant ( Ribes nigrum L.) and red and white currant ( Ribes rubrum L.) varieties were determined by silver-ion high-performance liquid chromatography and mass spectrometry. The aim was to investigate whether latitude and weather conditions affect the regioisomer compositions of Ala/L/L and Gla/L/L and whether the regioisomerism differs between species and varieties. In R. rubrum the proportion of the symmetric regioisomer LAlaL among Ala/L/L was higher (14.1%) than in R. nigrum (12.1%) (p < 0.001). Generally in currants, the proportion of LAlaL was lower (p < 0.001) in northern Finland (12.1%) than in southern Finland (13.5%), where temperature and radiation sums were higher. In R. rubrum varieties grown in the south, the proportion of LGlaL among Gla/L/L was significantly higher in the years 2005 and 2007 (30.7-32.0%) than in 2006 (24.2-25.4%), when temperature and radiation sums were higher and the amount of precipitation was lower.

Distribution of fatty acids in triacylglycerols and phospholipids from peas (Pisum sativum L.)

BACKGROUND

The fatty acid distribution of triacylglycerols (TAG) and major phospholipids (PL) obtained from four varieties of peas (Pisum sativum) was investigated. The total lipids extracted from the peas were separated by thin layer chromatography into seven fractions.

RESULTS

The major lipid components were PL (52.2-61.3%) and TAG (31.2-40.3%), while hydrocarbons, steryl esters, free fatty acids and diacylglycerols (sn-1,3 and sn-1,2) were also present in minor proportions (5.6-9.2%). The main PL components isolated from the four varieties were phosphatidylcholine (42.3-49.2%), phosphatidylinositol (23.3-25.2%) and phosphatidylethanolamine (17.7-20.5%). Significant differences (P < 0.05) in fatty acid distribution were found for different pea varieties. Phosphatidylinositol was unique in that it had the highest saturated fatty acid content among the three PL. However, the principal characteristics of the fatty acid distribution in the TAG and three PL were evident among the four varieties: unsaturated fatty acids were predominantly located in the sn-2 position while saturated fatty acids primarily occupied the sn-1 or sn-3 position in the oils of the peas.

CONCLUSION

These results should be useful to both producers and consumers for the manufacture of pea foods in Japan. Copyright © 2007 Society of Chemical Industry.