New insights in health effects oftrans α-linolenic acid isomers in humans

Highly sensitive method for the quantification of trans-linolenic acid isomers in trilinolenin of edible oils using an ionic liquid capillary column

BACKGROUND

The polarities of linolenic acid isomers are very similar, and only a few studies to date have attempted to separate α-linolenic acid (ALA) isomers completely. The aim of this study was to fill this gap by developing and validating an accurate method for the analysis of ALA isomers in trilinolenin at 200, 220 and 240 °C using a gas chromatograph-flame ionization detector equipped with an SLB-IL111 capillary column.

RESULTS

Results showed that eight ALA isomer standards were separated effectively using these optimized gas chromatographic conditions. The coefficient of determination was r² > 0.9994 in the linear range of each ALA isomer. The obtained limits of detection and limits of quantification of the ALA isomers were 0.02-0.08 ppm and 0.05-0.22 ppm, respectively. A high degree of reproducibility and percent recoveries between 96.2% and 106.5%, with coefficients of variation ranging from 0.82% to 0.97%, were achieved.

CONCLUSION

The developed method has been successfully applied to the analysis of ALA isomers in heated pure trilinolenin as well as to trilinolenin in various edible oils, and the TALA isomerization pathways in heated trilinolenin were verified. © 2017 Society of Chemical Industry.

ω-3 in meat products: benefits and effects on lipid oxidative stability

Although ω-3 intake has been associated with numerous health benefits, its addition to certain food matrices, and in particular meat products, may involve various technological barriers influencing the final quality of the products. Lipid oxidation must be highlighted due to the modification of both the sensory characteristics and the shelf-life of meat products. In order to reduce the impact of chemical changes and promote oxidative stability, the use of natural antioxidants has gained ground owing to the health and safety advantages linked to its effectiveness at reducing lipid oxidation. Many natural compounds have also been successfully tested in animal feed, in order to protect the raw meat materials and reduce the risk of lipid oxidation in processed products. This review aims to address the challenges and advantages of the incorporation of ω-3 fatty acids in raw meat materials and processed meat products, and to describe the use of different compounds to enhance lipid oxidative stability. © 2015 Society of Chemical Industry.

Novel characterisation of minor α-linolenic acid isomers in linseed oil by gas chromatography and covalent adduct chemical ionisation tandem mass spectrometry

Discrimination between polyunsaturated fatty acid isomers with three double bonds is a great challenge, due to structural similarities and similar polarities. In this study, we report the identification of four minor geometrical isomers of α-linolenic acid (ALA) present in linseed oil samples: (9E,12Z,15E)-, (9Z,12Z,15E)-, (9Z,12E,15Z)- and (9E,12Z,15Z)-octadeca-9,12,15-trienoic acids, chromatographically resolved by gas chromatography (GC) using a new and highly polar ionic phase column (SLB-IL111). Gas chromatography-electron ionisation mass spectrometry (GC-EIMS) determined that the four unknown compounds were C18:3 n-3 isomers. The positional 9-12-15 C18:3 configuration was achieved by covalent adduct chemical ionisation tandem mass spectrometry (CACI-MS/MS) while geometrical configuration was established with analytical standards based on relative retention. We hypothesised that these isomers are formed during linseed oil deodorisation and postulate preferred and unfavoured isomerisation pathways of ALA.

Ácidos graxos poliinsaturados ômega-3 e ômega-6: importância e ocorrência em alimentos

Os ácidos graxos poliinsaturados abrangem as famílias de ácidos graxos ômega-3 e ômega-6. Os ácidos graxos de cadeia muito longa, como os ácidos araquidônico e docosaexaenóico, desempenham importantes funções no desenvolvimento e funcionamento do cérebro e da retina. Esse grupo de ácidos graxos não pode ser obtido pela síntese de novo, mas pode ser sintetizado a partir dos ácidos linoléico e alfa-linolênico presentes na dieta. Neste artigo são considerados os principais fatores que podem inibir a atividade das enzimas dessaturases envolvidas na síntese dos ácidos graxos de cadeia muito longa. São apresentadas as recomendações da razão ômega-6/ômega-3 na dieta, propostas em diversos países, sendo verificada a convergência para o intervalo de 4 a 5:1. São relacionados alimentos que podem contribuir para aumentar a ingestão do ácido alfa-linolênico e dos ácidos graxos de cadeia muito longa. A essencialidade dos ácidos graxos de cadeia muito longa é muito dependente do metabolismo do indivíduo, sendo que a razão n-6/n-3 da dieta exerce grande influência nesse sentido.