regiospecific position of 18:1 cis and trans monoenoic fatty acids in milk fat triacylglycerols

• Published in: Journal of the American Oil Chemists' Society 2006-05, Vol.83 (5), p.407-413
• Main Authors: Kallio, H, Korkiasaari, K, Sjovall, O, Suomela, J.P, Linderborg, K
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Bovine; chemical analysis; cis‐monoenoic fatty acids; Differences; Fat industries; Fatty acids; Food industries; Fractionation; Fundamental and applied biological sciences. Psychology; Liquid chromatography; Methods; Milk; Milk and cheese industries. Ice creams; milk fat; monounsaturated fatty acids; Physical properties; reversed-phase high performance liquid chromatography; Samples; silver ion chromatography; Studies; tandem mass spectrometry; trans‐monoenoic fatty acids; triacylglycerols
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-006-1219-6

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.