The regiospecific position of 18∶1 cis and trans monoenoic fatty acids in milk fat triacylglycerols |
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Authors: | Heikki Kallio Kati Korkiasaari Olli Sjövall Jukka-Pekka Suomela Kaisa Linderborg |
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Affiliation: | (1) Department of Biochemistry and Food Chemistry, University of Turku, FI-20014 Turku, Finland |
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Abstract: | TAG of butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver-ion HPLC.
The fractions containing TAG with either cis-or trans-monoenoic FA were collected and fractionated further by reversed-phase HPLC to obtain fractions containing cis TAG of ACN:DB (acyl carbon number:double bonds) 48∶1, 50∶1, and 52∶1 as well as trans 48∶1, 50∶1, and 52∶1. The FA compositions of these fractions were elucidated by GC. The MW distribution of each fraction
was determined by ammonia negative-ion CI-MS. Each of the M-H]− parent ions was fractionated further by collision-induced dissociation with argon, which gave information on the location
of cis-and trans-FA between the primary and secondary positions of TAG. The results suggest that the sn-positions of the monoenoic cis-and trans-FA depend on the two other FA present in the molecule. With 14∶0 FA in the TAG molecule, the 18∶1 FA in the sn-2 position are mostly present as cis-isomers. When there is no 14∶0 in the TAG molecule, the trans-18∶1 isomers seem to be more common in the sn-2 position. Also when other long-chain FA are present, the trans-isomers are more likely to be located in the secondary (sn-2) position. |
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Keywords: | Bovine cis-monoenoic fatty acids milk fat reversed-phase high-performance liquid chromatography silver ion chromatography tandem mass spectrometry trans-monoenoic fatty acids triacylglycerols |
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