AWARD LECTURES Trans — and conjugated fatty acids in food — contents and analytical aspects

Hans Steinhart,Kirstin Winkler,Rainer Rickert

doi:10.1051/ocl.2001.0028

Hans Steinhart, Kirstin Winkler + Show 1 more

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https://doi.org/10.1051/ocl.2001.0028

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Abstract

The current investigations on fatty acids are focused on long chain fatty acids, trans fatty acids (TFA) and conjugated fatty acids (CFA), especially isomers of linoleic acid (CLA). This paper deals with the origins of TFA and CLA and their physiological significance. Furthermore an overview is given of analytical procedures of both TFA and CLA. In addition the contents and isomeric distribution of these groups of fatty acids in foods are presented.

Highlights

Summary : The current investigations on fatty acids are focused on long chain fatty acids, trans fatty acids (TFA) and conjugated fatty acids (CFA), especially isomers of linoleic acid (CLA)
Operating with this system it was possible to separate the hitherto not resolved trans8, cis10 from trans7, cis9 CLA-isomer (Figure 5) and the cis,trans and trans,cis isomers of 11,13 and 9,11. The identification of these unusual fatty acids was performed by mass spectrometry (MS) for the position of the double bond and Fourier transform infrared spectrometry (FTIR) for determination of the configuration
Predominant sources of TFA and CLA are foods from ruminants and partially hydrogenated vegetable oils. Because of their good physiological properties CLAs are predestined for use in functional food. This will be achieved by enrichment of fat containing products directly with CLA enriched oils or indirectly with raw material with higher amounts of CLA

Summary

Analysis of CLA

Before determination of individual isomers of CLA the fat is extracted from the matrix, followed by trans-esterification (Figure 4). Operating with this system it was possible to separate the hitherto not resolved trans, cis from trans, cis CLA-isomer (Figure 5) and the cis,trans and trans,cis isomers of 11,13 and 9,11 The identification of these unusual fatty acids was performed by mass spectrometry (MS) for the position of the double bond and Fourier transform infrared spectrometry (FTIR) for determination of the configuration (cis,cis; trans,trans; cis,trans; trans,cis). Prior to this a preparative RP-HPLC column was used to separate and to enrich conjugated metabolites of linoleic acid from CLA [17]. The distinction between cis,trans and trans,cis can be determined after partial reduction with hydrazine and separation of the resulting 18:1 FAMEs with GC-FID

Contents of TFA and CLA in foods

Findings

CONCLUSION