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Indelicato S, Di Stefano V, Avellone G, Piazzese D, Vazzana M, Mauro M, Arizza V, Bongiorno D. HPLC/HRMS and GC/MS for Triacylglycerols Characterization of Tuna Fish Oils Obtained from Green Extraction. Foods 2023; 12:foods12061193. [PMID: 36981119 PMCID: PMC10048091 DOI: 10.3390/foods12061193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023] Open
Abstract
Background: Fish oil is one of the most common lipidic substances that is consumed as a dietary supplement. The high omega-3 fatty acid content in fish oil is responsible for its numerous health benefits. Fish species such as mackerel, herring, tuna, and salmon are particularly rich in these lipids, which contain two essential omega-3 fatty acids, known as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Objectives: Due to the scarcity of information in the literature, this study aimed to conduct a qualitative and quantitative characterization of triglycerides (TAGs) in crude tuna fish oil using HPLC/HRMS. Fatty acid (FA) determination was also performed using GC/MS. The tuna fish oils analyzed were produced using a green, low-temperature process from the remnants of fish production, avoiding the use of any extraction solvents. Results: The analyses led to the tentative identification and semi-quantitation of 81 TAGs. In silico saponification and comparison with fatty acid methyl ester results helped to confirm the identified TAGs and their quantities. The study found that the produced oil is rich in EPA, DHA, and erucic acid, while the negligible isomerization of fatty acids to trans-derivatives was observed.
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Affiliation(s)
- Serena Indelicato
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Vita Di Stefano
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Giuseppe Avellone
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Daniela Piazzese
- Department of Earth and Marine Sciences (DISTEM), University of Palermo, Via Archirafi 22, 90123 Palermo, Italy
| | - Mirella Vazzana
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Manuela Mauro
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Vincenzo Arizza
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - David Bongiorno
- Department of Biological, Chemical and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Via Archirafi 32, 90123 Palermo, Italy
- Correspondence: ; Tel.: +39-09123891900
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Vetica F, Sansone A, Ferreri C, Chatgilialoglu C. A convenient route to mono-trans polyunsaturated free fatty acids. JOURNAL OF CHEMICAL RESEARCH 2022. [DOI: 10.1177/17475198221090908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Trans unsaturated fatty acids in humans may be originated both from dietary supplementation and from an endogenous free-radical-catalyzed cis−trans isomerization of fatty acid residues in naturally occurring cis lipids. The latter process affords geometrical isomers and the polyunsaturated fatty acid mono-trans isomers were demonstrated to be connected with stress conditions in living organisms. Synthesis of mono-trans polyunsaturated fatty acid is useful for analytical and biological research, and in this case, the availability of free fatty acids is needed as well as the possibility of mg scale of the synthetic protocol. Herein, we report a simple synthetic route to mono-trans isomers of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which includes thiyl radical-catalyzed isomerization reaction of polyunsaturated fatty acid methyl esters and fraction isolation of mono-trans mixture isomers followed by optimization of hydrolysis condition to free fatty acids and purification of each mono-trans polyunsaturated fatty acid. Our approach to mono-trans polyunsaturated fatty acids as free acids can reach the mg scale, thus fostering more applications to biochemical and biological studies.
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Affiliation(s)
- Fabrizio Vetica
- ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
| | - Anna Sansone
- ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy
| | - Carla Ferreri
- ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy
| | - Chryssostomos Chatgilialoglu
- ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy
- Center of Advanced Technologies, Adam Mickiewicz University, Poznań, Poland
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3
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Alves SP, Mendonça SH, Silva JL, Bessa RJB. Nannochloropsis oceanica, a novel natural source of rumen-protected eicosapentaenoic acid (EPA) for ruminants. Sci Rep 2018; 8:10269. [PMID: 29980726 PMCID: PMC6035222 DOI: 10.1038/s41598-018-28576-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 06/26/2018] [Indexed: 02/07/2023] Open
Abstract
We hypothesize that whole microalga biomass is a natural rumen-protected source of eicosapentaenoic acid (EPA, 20:5n-3) for ruminants. To test our hypothesis, we studied the ruminal biohydrogenation of EPA from two microalgae, Nannochloropsis oceanica and Phaeodactylum tricornutum using in vitro incubations with rumen fluid. A total mixed ration was incubated with: no EPA (control), EPA as free-fatty acid, N. oceanica spray-dried (SD), N. oceanica freeze-dried (FD), or P. tricornutum FD. The kinetics of EPA disappearance and of products formed during the 24 hours of incubation were evaluated, and complemented by deuterated-EPA incubation. Results showed that EPA metabolism from the N. oceanica was remarkably reduced compared with the P. tricornutum and free-EPA, and this reduction was even more effective with the N. oceanica FD. Our data also indicates that neither feed dry matter disappearance nor rumen microbial markers (branched-chain fatty acids and dimethyl acetals) were affected by EPA-sources. We reported for the first time the kinetics of EPA biohydrogenation class products and the unequivocal formation of 20:0 from EPA. Overall, N. oceanica shows a strong potential to be used as a natural dietary source of EPA to ruminants, nevertheless further studies are needed to verify its protection in vivo.
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Affiliation(s)
- Susana P Alves
- CIISA - Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisboa, Portugal.
| | - Sofia H Mendonça
- ALLMICROALGAE, Av. Eng. Duarte Pacheco 19, 9° piso, 1070-100, Lisboa, Portugal
| | - Joana L Silva
- ALLMICROALGAE, Av. Eng. Duarte Pacheco 19, 9° piso, 1070-100, Lisboa, Portugal
| | - Rui J B Bessa
- CIISA - Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisboa, Portugal
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4
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Menounou G, Giacometti G, Scanferlato R, Dambruoso P, Sansone A, Tueros I, Amézaga J, Chatgilialoglu C, Ferreri C. Trans Lipid Library: Synthesis of Docosahexaenoic Acid (DHA) Monotrans Isomers and Regioisomer Identification in DHA-Containing Supplements. Chem Res Toxicol 2018; 31:191-200. [PMID: 29485870 DOI: 10.1021/acs.chemrestox.8b00021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Docosahexaenoic acid (DHA) is a semiessential polyunsaturated fatty acid (PUFA) for eukaryotic cells that is found in natural sources such as fish and algal oils and widely used as an ingredient for omega-3 containing foods or supplements. DHA effects are connected to its natural structure with six cis double bonds, but geometrical monotrans isomers can be formed during distillation or deodorization processes, as an unwanted event that alters molecular characteristics and annihilates health benefits. The characterization of the six monotrans DHA regioisomers is an open issue to address for analytical, biological, and nutraceutical applications. Here we report the preparation, separation, and first identification of each isomer by a dual approach consisting of the following: (i) the direct thiyl radical-catalyzed isomerization of cis-DHA methyl ester and (ii) the two-step synthesis from cis-DHA methyl ester via monoepoxides as intermediates, which are separated and identified by nuclear magnetic resonance spectroscopy, followed by elimination for the unequivocal assignment of the double bond position. This monotrans DHA isomer library with NMR and GC analytical characterization was also used to examine the products of thiyl-radical-catalyzed isomerization of a fish oil sample and to evaluate the trans isomer content in omega-3 containing supplements commercially available in Italy and Spain.
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Affiliation(s)
- Georgia Menounou
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
| | - Giorgia Giacometti
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
| | - Roberta Scanferlato
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
| | - Paolo Dambruoso
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
| | - Anna Sansone
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
| | - Itziar Tueros
- AZTI, Food and Health, Parque Tecnológico de Bizkaia , Astondo Bidea 609 , 48160 Derio , Spain
| | - Javier Amézaga
- AZTI, Food and Health, Parque Tecnológico de Bizkaia , Astondo Bidea 609 , 48160 Derio , Spain
| | | | - Carla Ferreri
- ISOF, Consiglio Nazionale delle Ricerche , Via P. Gobetti 101 , 40129 Bologna , Italy
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Aldai N, Delmonte P, Alves SP, Bessa RJB, Kramer JKG. Evidence for the Initial Steps of DHA Biohydrogenation by Mixed Ruminal Microorganisms from Sheep Involves Formation of Conjugated Fatty Acids. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:842-855. [PMID: 29291262 DOI: 10.1021/acs.jafc.7b04563] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Incubation of DHA with sheep rumen fluid resulted in 80% disappearance in 6 h. The products were analyzed as their fatty acid (FA) methyl esters by GC-FID on SP-2560 and SLB-IL111 columns. The GC-online reduction × GC and GC-MS techniques demonstrated that all DHA metabolites retained the C22 structure (no evidence of chain-shortening). Two new transient DHA products were identified: mono-trans methylene interrupted-DHA and monoconjugated DHA (MC-DHA) isomers. Identification of MC-DHA was confirmed by their predicted elution using equivalent chain length differences from C18 FA, their molecular ions, and the 22:5 products formed which were the most abundant at 6 h. The 22:5 structures were established by fragmentation of their 4,4-dimethyloxazoline derivatives, and all 22:5 products contained an isolated double bond, suggesting formation via MC-DHA. The most abundant c4,c7,c10,t14,c19-22:5 appeared to be formed by unknown isomerases. Results suggest that the initial biohydrogenation of DHA was analogous to that of C18 FA.
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Affiliation(s)
- Noelia Aldai
- Department of Pharmacy and Food Sciences, University of the Basque Country (UPV/EHU) , Paseo de la Universidad 7, 01006 Vitoria-Gasteiz, Spain
| | - Pierluigi Delmonte
- Office of Regulatory Science, Centre for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States
| | - Susana P Alves
- CIISA, Faculty of Veterinary Medicine, University of Lisbon , Av. da Universidade Técnica, 1300-477 Lisbon, Portugal
| | - Rui J B Bessa
- CIISA, Faculty of Veterinary Medicine, University of Lisbon , Av. da Universidade Técnica, 1300-477 Lisbon, Portugal
| | - John K G Kramer
- Guelph Food Research Centre, Agriculture and Agri-Food Canada , Guelph N1G 5C9, Ontario, Canada
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6
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Yurchenko S, Sats A, Poikalainen V, Karus A. Method for determination of fatty acids in bovine colostrum using GC-FID. Food Chem 2016; 212:117-22. [DOI: 10.1016/j.foodchem.2016.05.103] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/28/2016] [Accepted: 05/16/2016] [Indexed: 11/17/2022]
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7
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Chin ST, Eyres GT, Marriott PJ. Application of integrated comprehensive/multidimensional gas chromatography with mass spectrometry and olfactometry for aroma analysis in wine and coffee. Food Chem 2015; 185:355-61. [DOI: 10.1016/j.foodchem.2015.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 12/09/2014] [Accepted: 04/03/2015] [Indexed: 10/23/2022]
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8
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Mendoza LG, González-Álvarez J, Gonzalo CF, Arias-Abrodo P, Altava B, Luis SV, Burguete MI, Gutiérrez-Álvarez MD. Gas chromatographic analysis of fatty acid methyl esters of milk fat by an ionic liquid derived from L-phenylalanine as the stationary phase. Talanta 2015; 143:212-218. [DOI: 10.1016/j.talanta.2015.05.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/12/2015] [Accepted: 05/15/2015] [Indexed: 10/23/2022]
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9
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Belaunzaran X, Bravo‐Lamas L, Kramer JKG, Aldai N. Limitation of using silver ion solid‐phase extraction for animal lipids with a low
trans
content. EUR J LIPID SCI TECH 2014. [DOI: 10.1002/ejlt.201400163] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xabier Belaunzaran
- Department of Pharmacy and Food SciencesLascaray Research CentreUniversity of the Basque Country (UPV/EHU)01006Vitoria‐GasteizSpain
| | - Leire Bravo‐Lamas
- Department of Pharmacy and Food SciencesLascaray Research CentreUniversity of the Basque Country (UPV/EHU)01006Vitoria‐GasteizSpain
| | - John K. G. Kramer
- Guelph Food Research CentreAgriculture & Agri‐Food CanadaGuelphON, Canada (retired)
| | - Noelia Aldai
- Department of Pharmacy and Food SciencesLascaray Research CentreUniversity of the Basque Country (UPV/EHU)01006Vitoria‐GasteizSpain
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10
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Shibamoto S, Gooley A, Yamamoto K. Separation behavior of octadecadienoic acid isomers and identification of cis- and trans-isomers using gas chromatography. Lipids 2014; 50:85-100. [PMID: 25466915 DOI: 10.1007/s11745-014-3966-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 10/15/2014] [Indexed: 11/28/2022]
Abstract
Using a strongly polar cyanopropyl capillary column we have investigated the gas chromatography (GC) separation behaviors of 24 octadecadienoic acid methyl ester (18:2ME) isomers compared against saturated methyl stearate (18:0ME) and arachidic acid methyl ester (20:0ME), and the dependency on the GC column temperature. The 24 isomers were obtained by performing cis-to trans-isomerization of six regioisomers: five of the 18:2ME isomers were prepared by the partial reduction of methyl α-linolenate and methyl γ-linolenate C18 trienoic acids with different double bond positions, whereas the sixth isomer, 18:2ME (c5, c9), was obtained from a raw constituent fatty acid methyl ester (FAME) sample extracted from Japanese yew seeds. There are no reference standards commercially available for 18:2ME isomers, and in elucidating the elution order of these isomers this study should help the future identification of cis- and trans-type of 18:2ME. We also report the identification method of cis- and trans-type of FAME using equivalent chain lengths and attempt the identification of cis- and trans-type of 18:2ME isomers from partially hydrogenated canola oil.
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Affiliation(s)
- Shigeaki Shibamoto
- Shimadzu Corporation, 3-9-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto, 619-0237, Japan,
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11
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Lin CC, Wasta Z, Mjøs SA. Evaluation of the retention pattern on ionic liquid columns for gas chromatographic analyses of fatty acid methyl esters. J Chromatogr A 2014; 1350:83-91. [DOI: 10.1016/j.chroma.2014.05.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/04/2014] [Accepted: 05/08/2014] [Indexed: 11/28/2022]
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12
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Yoshinaga K, Asanuma M, Xu C, Mizobe H, Kojima K, Nagai T, Beppu F, Gotoh N. Resolution behavior of cis- and trans-octadecenoic acid isomers by AOCS official method using SP-2560 column. J Oleo Sci 2014; 62:781-8. [PMID: 24088515 DOI: 10.5650/jos.62.781] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The gas chromatography-flame ionization detector equipped with a higher polarity column (i.e., SP-2560) has often been used for the quantification of trans-fatty acids in food. In particular, AOCS Ce 1h-05, the official method of the American Oil Chemists' Society (AOCS), is a highly effective method to separate the isomers of trans-fatty acids. In this study, the resolution behavior and the response factors of cis- and trans-octadecenoic acid methyl ester (C18:1-ME) isomers separated by the AOCS Ce 1h-05 method were investigated, and the contents of each cis- and trans-C18:1-ME isomer in partially hydrogenated vegetable oil (PHVO) and milk fat were quantified by using the calibration curves obtained for the respective isomers. The relative response factors for the trans- and cis-C18:1-ME isomers against the internal standard heneicosanoic acid methyl ester (C21:0-ME) were 1.031 ± 0.040 (mean ± SD) and 0.990 ± 0.032, respectively. The relative response factors of trans-isomers tend to be higher than those of cis-C18:1-ME isomers. The peaks of cis-4-C18:1-ME, cis-5-C18:1-ME, cis-6-C18:1-ME, cis-7-C18:1-ME, cis-8-C18:1-ME, and cis-9-C18:1-ME isomers overlapped with those of trans-C18:1-ME isomers. Both PHVO and milk fat contained many types of cis- and trans-C18:1 isomers, and the total contents of the trans-C18:1 isomer in PHVO and milk fat were 28.01 g and 3.62 g per 100 g oil, respectively. When the trans-C18:1-ME isomer was separated from the cis-C18:1-ME by using a silver-ion cartridge column before the analyses, the total contents of the trans-C18:1 isomer in PHVO and milk fat were 23.03 g and 2.78 g per 100 g oil, respectively. The difference in the trans-C18:1 isomer content between the two methods was ascribed to the partial overlapping of cis-isomer peaks with the peaks of trans-C18:1-ME isomers, in the chromatogram.
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13
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Kraft J, Kramer JK, Hernandez M, Letarte J, Aldai N, Sandercole V, Mohammed R, Mayer F, Mossoba MM, Delmonte P. Silver ion solid-phase extraction chromatography for the analysis oftransfatty acids. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/lite.201400008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jana Kraft
- Department of Animal Science; University of Vermont; Burlington VT
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14
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Chatgilialoglu C, Ferreri C, Melchiorre M, Sansone A, Torreggiani A. Lipid geometrical isomerism: from chemistry to biology and diagnostics. Chem Rev 2013; 114:255-84. [PMID: 24050531 DOI: 10.1021/cr4002287] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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15
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A database of chromatographic properties and mass spectra of fatty acid methyl esters from omega-3 products. J Chromatogr A 2013; 1299:94-102. [DOI: 10.1016/j.chroma.2013.05.056] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Revised: 05/09/2013] [Accepted: 05/22/2013] [Indexed: 11/21/2022]
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16
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Reshma MV, Ravi Kiran C, Sundaresan A. Separation of cis/trans fatty acid isomers on gas chromatography compared to the Ag-TLC method. GRASAS Y ACEITES 2013. [DOI: 10.3989/gya.073312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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17
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Trans Isomers of EPA and DHA in Omega-3 Products on the European Market. Lipids 2012; 47:659-67. [DOI: 10.1007/s11745-012-3672-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 04/03/2012] [Indexed: 10/28/2022]
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18
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Dhibi M, Issaoui M, Brahmi F, Mechri B, Mnari A, Cheraif I, Skhiri F, Gazzah N, Hammami M. Nutritional quality of fresh and heated Aleppo pine (Pinus halepensis Mill.) seed oil: trans-fatty acid isomers profiles and antioxidant properties. Journal of Food Science and Technology 2012; 51:1442-52. [PMID: 25114334 DOI: 10.1007/s13197-012-0664-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 12/24/2011] [Accepted: 02/15/2012] [Indexed: 01/18/2023]
Abstract
Numerous studies have focused on trans fatty acids (TFA) technologically produced by partial hydrogenation of oils. However, TFA can also be present in fresh oils. For this reason, cis fatty acid (CFA), TFA and conjugated linoleic acid (CLA) of fresh and heated Aleppo pine seed oil (APSO) at frying temperature (180 °C) were evaluated and correlated with the antioxidant characteristics. Results showed that fresh APSO had a low oleic/linoleic ratio O/L (0.4). Total TFA in fresh APSO reached 1%. The predominant TFA was 18:2 n-6 (t9, t12) in both fresh and heated APSO. Individual TFA increased with significant differences (p < 0.05) with heating time. CLA occurred after 4 h and significantly increased (p < 0.05) accounting 10% of total TFA after 10 h. Total TFA are negatively correlated with α-tocopherol, γ-tocopherol (p < 0.05) and carotenoïds (p < 0.01) and positively correlated with remaining DPPH. Oil stability index (OSI) showed significant negative correlation with TFA (r = -0.925; p = 0.008). A principal component analysis (PCA) showed a clear discrimination between fresh and heated oils. Temperature, heating time, unsaturation degree and antioxidants are combined factors which significantly affect the isomerization rate and nutritional quality of APSO.
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Affiliation(s)
- Madiha Dhibi
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Manel Issaoui
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Faten Brahmi
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Beligh Mechri
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Amira Mnari
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Imed Cheraif
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Fathia Skhiri
- Biotechnology High Institute of Monastir, Monastir, Tunisia
| | - Noureddine Gazzah
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
| | - Mohamed Hammami
- Laboratory of Biochemistry, UR "Human Nutrition and Metabolic Disorders" Faculty of Medicine, University of Monastir, 5019 Monastir, Tunisia
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19
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Santercole V, Delmonte P, Kramer JKG. Comparison of Separations of Fatty Acids from Fish Products Using a 30-m Supelcowax-10 and a 100-m SP-2560 Column. Lipids 2012; 47:329-44. [DOI: 10.1007/s11745-011-3645-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 12/12/2011] [Indexed: 11/29/2022]
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20
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Alves SP, Tyburczy C, Lawrence P, Bessa RJB, Brenna JT. Acetonitrile covalent adduct chemical ionization tandem mass spectrometry of non-methylene-interrupted pentaene fatty acid methyl esters. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:1933-1941. [PMID: 21698676 DOI: 10.1002/rcm.5065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Acetonitrile covalent adduct chemical ionization tandem mass spectrometry (CACIMS/MS) has shown to be an efficient method for the identification of double-bond position in homoallylic, conjugated and several polyene non-methylene-interrupted (NMI) fatty acid methyl esters. However, it has not been thoroughly evaluated for NMI highly unsaturated fatty acids (HUFA) with more than four double bonds. Docosahexaenoic acid (DHA)-rich single cell oil (DHASCO(®); Martek Biosciences, Corp.) was partially hydrogenated (partially hydrogenated DHASCO; PHDO) producing ten novel 22:5 and 22:6 HUFA isomers. In single-stage MS, the ratio of [M+54](+)/[M+54-32](+) for the 22:5 and 22:6 isomers indicated the presence of homoallylic or partially conjugated double-bond systems. The CACIMS/MS spectra revealed six 22:5 isomers with diagnostic ions corresponding to the homoallylic 22:5n-6 and 22:5n-3 isomers, and four distinct NMI 22:5 isomers. Diagnostic ions for four 22:6 isomers were identical to the native DHA illustrating that CACIMS/MS is sensitive to double-bond position but not geometry. Three gas chromatography (GC) peaks for partially conjugated 22:6 isomers were also detected and clearly distinguishable from homoallylic 22:6 isomers, but their CACIMS/MS spectra did not yield prominent ions indicative of double-bond position, possibly due to co-elution. Overall, CACIMS/MS was effective for determining double-bond position in NMI 22:5 isomers. Further investigations are warranted to evaluate and determine fragmentation patterns for partially conjugated and NMI 22:6 HUFA.
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Affiliation(s)
- Susana P Alves
- INRB - Instituto Nacional dos Recursos Biológicos, Unidade de Produção Animal, Fonte-Boa, 2005-048 Vale de Santarém, Portugal
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Quehenberger O, Armando AM, Dennis EA. High sensitivity quantitative lipidomics analysis of fatty acids in biological samples by gas chromatography-mass spectrometry. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:648-56. [PMID: 21787881 DOI: 10.1016/j.bbalip.2011.07.006] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 06/21/2011] [Accepted: 07/11/2011] [Indexed: 12/21/2022]
Abstract
Historically considered to be simple membrane components serving as structural elements and energy storing entities, fatty acids are now increasingly recognized as potent signaling molecules involved in many metabolic processes. Quantitative determination of fatty acids and exploration of fatty acid profiles have become common place in lipid analysis. We present here a reliable and sensitive method for comprehensive analysis of free fatty acids and fatty acid composition of complex lipids in biological material. The separation and quantitation of fatty acids are achieved by capillary gas chromatography. The analytical method uses pentafluorobenzyl bromide derivatization and negative chemical ionization gas chromatography-mass spectrometry. The chromatographic procedure provides base line separation between saturated and unsaturated fatty acids of different chain lengths as well as between most positional isomers. Fatty acids are extracted in the presence of isotope-labeled internal standards for high quantitation accuracy. Mass spectrometer conditions are optimized for broad detection capacity and sensitivity capable of measuring trace amounts of fatty acids in complex biological samples. .
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Affiliation(s)
- Oswald Quehenberger
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0601, USA.
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Mjøs SA, Haugsgjerd BO. Trans fatty acid analyses in samples of marine origin: the risk of false positives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:3520-3531. [PMID: 21370819 DOI: 10.1021/jf104156v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
At conditions commonly applied for trans fatty analyses by gas chromatography, fatty acids naturally occurring in marine lipids may overlap chromatographically with C16 and C18 trans fatty acids and lead to false positives. Elution patterns were studied by tracking retention indices at shifting temperature conditions on two cyanopropyl-coated capillary columns. Most overlaps can be avoided by selecting the right chromatographic conditions, but it was not possible to find a single condition that eliminates the risk of overlap between trans fatty acids and interferents. In total, 17 compounds were identified as potential interferents, and the amounts of these compounds were quantified in various samples of marine origin. The interferents that will most likely contribute to incorrect assessments of trans fatty acids in marine lipids are probably 18:3 n-4 and 18:1 n-11.
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Affiliation(s)
- Svein A Mjøs
- Nofima BioLab, Kjerreidviken 15, N-5141 Fyllingsdalen, Bergen, Norway.
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23
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Dhibi M, Mechri B, Cheraif I, Hammami M. trans-Fatty acid isomers in two sesame (Sesamum indicum L.) seed byproducts under processing. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:12210-12215. [PMID: 21049945 DOI: 10.1021/jf102621c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The present study has been inspired by the growing need for rigorously controlling the nutritional quality and safety of food products. The impact of application in the food industry on fatty acids composition, trans-fatty acids (TFAs), and conjugated linoleic acid (CLA) profiles were investigated in a highly consumed candy byproduct of sesame seed (chamia) in comparison to fresh sesame seed oil (SSO) and heated SSO under simulated frying experiments. The effect of treatment on SSO was studied by determining the TFA and CLA changes. Results showed significant differences between the two byproducts in TFA and CLA amounts. Total TFAs were found to be significantly higher in chamia than fresh SSO (1.31 versus 0.066%, respectively; p < 0.05) and even higher than all heated SSO from 2 to 10 h at 180 °C (1.31 versus 0.33%, respectively; p < 0.05). A significant linear relationship was found between trans-monounsaturated fatty acid (MUFA), trans-polyunsaturated fatty acid (PUFA), and total TFA and the time of processing, with a correlation coefficient (R(2)) greater than 0.9 for TFA and PUFA, with a higher correlation assigned to PUFA (r = 0.988; p < 0.001), followed by TFA (r = 0.959; p < 0.01) and MUFA (r = 0.844; p < 0.05). Principal component analysis of the fatty acid (FA) profiles showed discrimination between chamia and both fresh and heated SSO. A high stability of SSO against isomerization reactions as compared to their chamia sample counterpart has been noted. These findings suggest that the food industry engenders relatively higher changes in fatty acid configurations than the frying process.
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Affiliation(s)
- Madiha Dhibi
- Laboratory of Biochemistry, UR03/ES08 "Human Nutrition and Metabolic Disorders", Faculty of Medicine, 5019 Monastir, Tunisia
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24
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Šegan S, Opsenica D, Šolaja B, Milojković-Opsenica D. Planar chromatography of cholic acid-derivedcis-transisomeric bis-steroidal tetraoxanes. JPC-J PLANAR CHROMAT 2009. [DOI: 10.1556/jpc.22.2009.3.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Alves SP, Bessa RJ. Comparison of two gas–liquid chromatograph columns for the analysis of fatty acids in ruminant meat. J Chromatogr A 2009; 1216:5130-9. [DOI: 10.1016/j.chroma.2009.04.079] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 04/15/2009] [Accepted: 04/24/2009] [Indexed: 10/20/2022]
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Ruiz-Rodriguez A, Reglero G, Ibañez E. Recent trends in the advanced analysis of bioactive fatty acids. J Pharm Biomed Anal 2009; 51:305-26. [PMID: 19525080 DOI: 10.1016/j.jpba.2009.05.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 05/13/2009] [Accepted: 05/14/2009] [Indexed: 12/15/2022]
Abstract
The consumption of dietary fats have been long associated to chronic diseases such as obesity, diabetes, cancer, arthritis, asthma, and cardiovascular disease; although some controversy still exists in the role of dietary fats in human health, certain fats have demonstrated their positive effect in the modulation of abnormal fatty acid and eicosanoid metabolism, both of them associated to chronic diseases. Among the different fats, some fatty acids can be used as functional ingredients such as alpha-linolenic acid (ALA), arachidonic acid (AA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), gamma-linolenic acid (GLA), stearidonic acid (STA) and conjugated linoleic acid (CLA), among others. The present review is focused on recent developments in FAs analysis, covering sample preparation methods such as extraction, fractionation and derivatization as well as new advances in chromatographic methods such as GC and HPLC. Special attention is paid to trans fatty acids due its increasing interest for the food industry.
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Affiliation(s)
- Alejandro Ruiz-Rodriguez
- Departamento de Caracterización de Alimentos, Instituto de Fermentaciones Industriales, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain
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Ferreri C, Chatgilialoglu C. Membrane lipidomics and the geometry of unsaturated fatty acids from biomimetic models to biological consequences. Methods Mol Biol 2009; 579:391-411. [PMID: 19763487 DOI: 10.1007/978-1-60761-322-0_20] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In the last decades, free radical processes delineated an interdisciplinary field linking chemistry to biology and medicine. Free radical mechanisms became of importance as molecular basis of physiological and pathological conditions. Lipids, in particular, unsaturated fatty acids, are susceptible of free radical attack. The reactivity of the double bond toward free radicals is well known, in particular the reversible addition of radical species to this functionality determines the cis-trans double bond isomerization. Since the prevalent geometry displayed by unsaturated fatty acids in eukaryotes is cis, the occurrence of the cis-trans isomerization by free radicals corresponds to the loss of an important structural information linked to biological activity. The formation of trans isomers can have important meaning and consequences connected to radical stress. Free radical isomerization of membrane fatty acids has been the subject of research coupling the top-down approach by model studies, such as biomimetic chemistry in liposomes, with the bottom-up approach dealing with the examination of cell membrane lipidome in living systems under several physiopathological conditions. Methodologies and molecular libraries have been settled, for both liposome experiments and the examination of the radical stress in biological membranes. This chapter will give an overview of the current procedures used for liposome models and the cis-trans isomerization experiments, in order to build-up a library of trans geometrical fatty acid isomers.
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Affiliation(s)
- Carla Ferreri
- ISOF-BioFree Radicals, Consiglio Nazionale delle Riceriche, Bologna, Italy
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Mjøs SA. Retention behavior oftrans isomers of eicosapentaenoic and docosahexaenoic acid methyl esters on a polyethylene glycol stationary phase. EUR J LIPID SCI TECH 2008. [DOI: 10.1002/ejlt.200700225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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29
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Martin CA, de Oliveira CC, Visentainer JV, Matsushita M, de Souza NE. Optimization of the selectivity of a cyanopropyl stationary phase for the gas chromatographic analysis of trans fatty acids. J Chromatogr A 2008; 1194:111-7. [DOI: 10.1016/j.chroma.2008.04.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 04/07/2008] [Accepted: 04/17/2008] [Indexed: 11/26/2022]
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30
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Fournier V, Destaillats F, Hug B, Golay PA, Joffre F, Juanéda P, Sémon E, Dionisi F, Lambelet P, Sébédio JL, Berdeaux O. Quantification of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization by gas–liquid chromatography. J Chromatogr A 2007; 1154:353-9. [PMID: 17449039 DOI: 10.1016/j.chroma.2007.03.099] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 03/27/2007] [Accepted: 03/27/2007] [Indexed: 11/28/2022]
Abstract
Long-chain polyunsaturated fatty acids (LC-PUFAs) of the n-3 series and especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively) have important biological properties. The main dietary sources of LC-PUFAs are fish and fish oil. Geometrical isomerization is one of the main reactions happening during the thermal treatment of polyunsaturated fatty acids. Refined fish oils are used to supplement food products in LC-PUFAs and the quality of these nutritional ingredients have to be controlled. In the present study, a suitable method for the quantification of EPA and DHA geometrical isomers in fish oils by gas-liquid chromatography (GC) is presented. A highly polar capillary column (CP-Sil 88, 100 m) operating under optimal conditions was used. Method selectivity was studied by GC-mass spectrometry. The performance characteristics of the quantification method were studied using samples of fish oil deodorized at 220 degrees C for 3 h. The linearity of the method was assessed by analyzing composite samples obtained by mixing fish oil deodorized at 220 degrees C with semi-refined fish oil (control). Precision was evaluated by analyzing the same samples in triplicate. Results showed that the validated method is suitable to quantify low amounts of geometrical (trans) isomers of EPA and DHA in refined fish oils. The limits of quantification of the EPA and DHA geometrical isomers are 0.16 and 0.56 g/100 g of fish oil, for EPA and DHA, respectively. Commercially available LC-PUFA oil samples were evaluated by using the validated method. The results show that the oils analyzed contain low amounts (<1% of total fatty acids) of geometrical isomers of EPA and DHA.
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Fournier V, Destaillats F, Lambelet P, Dionisi F, Sébédio JL, Berdeaux O. Degradation products formed from long-chain PUFA during deodorization of fish oil. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/lite.200600003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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32
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Fournier V, Juanéda P, Destaillats F, Dionisi F, Lambelet P, Sébédio JL, Berdeaux O. Analysis of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization. J Chromatogr A 2006; 1129:21-8. [PMID: 16893549 DOI: 10.1016/j.chroma.2006.06.089] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 06/18/2006] [Accepted: 06/26/2006] [Indexed: 11/27/2022]
Abstract
Addition of long-chain polyunsaturated fatty acids (LC-PUFAs) from marine oil into food products implies preliminary refining procedures of the oil which thermal process affects the integrity of LC-PUFAs. Deodorization, the major step involving high temperatures, is a common process used for the refining of edible fats and oils. The present study evaluates the effect of deodorization temperature on the formation of LC-PUFA geometrical isomers. Chemically isomerized eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as reference samples. Fish oil samples have been deodorized at 180, 220 and 250 degrees C for 3 h and pure EPA and DHA fatty acid methyl esters (FAMEs) were chemically isomerized using p-toluenesulfinic acid as catalyst. FAMEs prepared from fish oil were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC). Geometrical isomers produced by both processes were fractionated by silver-ion thin-layer chromatography (Ag-TLC) and silver-ion high-performance liquid chromatography (Ag-HPLC). The FAME fractions were subsequently analyzed by gas chromatography (GC) on a 100 m highly polar cyanopropylpolysiloxane coated capillary column, CP-Sil 88. Our results show that thermally induced geometrical isomerization appears to be a directed reaction and some ethylenic double bond positions on the hydrocarbon chain are more prone to stereomutation. Only minor changes were observed in the EPA and DHA trans isomers content and distribution after deodorization at 180 degrees C. The analyses of EPA and DHA isomer fractions revealed that it is possible to quantify EPA geometrical isomers by GC using the described conditions. However, we notice that a mono-trans isomer of DHA, formed during both chemical and thermal treatments, co-elute with all-cis DHA. This feature should be taken into consideration for the quantification of DHA geometrical isomers.
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Affiliation(s)
- Véronique Fournier
- UMR FLAVIC Department, INRA, 17 Rue Sully BP 86510, 21065 Dijon, Cedex, France
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Mjøs SA. Prediction of equivalent chain lengths from two-dimensional fatty acid retention indices. J Chromatogr A 2006; 1122:249-54. [PMID: 16701676 DOI: 10.1016/j.chroma.2006.04.067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 04/20/2006] [Accepted: 04/25/2006] [Indexed: 10/24/2022]
Abstract
A recently introduced two-dimensional fatty acid retention index system (2D-FARI) was used as basis for prediction of equivalent chain lengths (ECL) of fatty acid methyl esters (FAME) on a BPX-70 stationary phase. Models for the relationship between 2D-FARI data and ECL values of a calibration sample with 30 common fatty acids were established by a simple multivariate regression. The models were thereafter applied on 2D-FARI data for other FAMEs and used to predict the ECLs for these compounds. The 2D-FARI values for the fatty acids in the calibration sample are given by definition. Thus, the only information necessary to calculate the ECL value for a compound run under identical conditions as the calibration sample is the 2D-FARI values for the compound, which can be acquired from literature data. The method was validated with test sets analysed with different temperature and flow programs. ECLs of various marine FAME and trans isomers of Eicosapentaenoic and Docosahexaenoic acid were predicted with root mean squared error of prediction from 0.002 to 0.012 ECL units.
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Affiliation(s)
- Svein A Mjøs
- Norwegian Institute of Fisheries and Aquaculture Research, Department SFF, Kjerreidviken 16, N-5141 Fyllingsdalen, Bergen, Norway.
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Mjøs SA, Solvang M. Geometrical isomerisation of eicosapentaenoic and docosahexaenoic acid at high temperatures. EUR J LIPID SCI TECH 2006. [DOI: 10.1002/ejlt.200600055] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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35
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Mjøs SA, Meier S, Grahl-Nielsen O. Geometrical isomerisation of double bonds in acid-catalysed preparation of fatty acid methyl esters. EUR J LIPID SCI TECH 2006. [DOI: 10.1002/ejlt.200500298] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Mjøs SA, Grahl-Nielsen O. Prediction of gas chromatographic retention of polyunsaturated fatty acid methyl esters. J Chromatogr A 2006; 1110:171-80. [PMID: 16460747 DOI: 10.1016/j.chroma.2006.01.092] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 01/17/2006] [Accepted: 01/19/2006] [Indexed: 11/26/2022]
Abstract
Multivariate regression models were applied to predict retention indices as equivalent chain lengths (ECL) for methylene-interrupted polyunsaturated fatty acids. Simple molecular descriptors, the chain length, the number of double bonds and the position of the double bond system, were used as predictors. The merits of different variable combinations were evaluated. For general models, it was necessary to include the distance from the double bond system to both the carbonyl group (Delta-position) and the methyl end of the fatty acid (n-position). The best accuracy was found for models including higher order terms of Delta and n. For models restricted to n-3 and n-6 isomers, it was not necessary to include the n-position among the variables. The highest residuals for the most accurate models were below 0.06 ECL units, and root mean square error of prediction was below 0.030. The ECL data was achieved by three different temperature programs on a cyanopropyl column.
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Affiliation(s)
- Svein A Mjøs
- Fiskeriforskning, Kjerreidviken 16, N-5141 Fyllingsdalen, Norway.
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