title: Regioisomerism of triacylglycerols in lard, tallow, yolk, chicken skin, palm oil, palm olein, palm stearin, and a transesterified blend of palm stearin and coconut oil analyzed by tandem mass spectrometry.
abstract: Triacylglycerols (TAG) of lard, tallow, egg yolk, chicken skin, palm oil, palm olein, palm stearin, and a transesterified blend of palm stearin and coconut oil (82:18) were investigated by chemical ionization and collision-induced dissociation tandem mass spectrometry. Accurate molecular level information of the regioisomeric structures of individual TAGs was achieved. When existing in a TAG molecule of lard, palmitic acid occupied 90-100% of the sn-2 position. Within the major fatty acid combinations in tallow TAGs, the secondary position sn-2 was preferentially occupied in the decreasing order by oleoyl > palmitoyl > stearoyl residues, the order in saturated TAGs being myristoyl > stearoyl = palmitoyl. TAGs in egg yolk were more asymmetric than in chicken skin, with linoleic acid highly specifically attached in the yolk sn-2 carbon. Nearly 50% of yolk TAGs contained 52 carbon atoms with two or three double bonds. Linoleic, oleic, and palmitic acids were in the sn-2 location in decreasing quantities in palm oil and its fractions. Triacylglycerols of equal molecular weight behaved similarly in the fractionation process. Randomization of the parent oil TAGs was seen in the transesterified oil. The tandem mass spectrometric analysis applied provided detailed information of the distribution of fatty acids in individual combinations in TAGs.
authors.affiliation: Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku, Finland. heikki.kallio@utu.fi
authors.forename: H
authors.initials: H
authors.lastname: Kallio
authors.forename: K
authors.initials: K
authors.lastname: Yli-Jokipii
authors.forename: J P
authors.initials: JP
authors.lastname: Kurvinen
authors.forename: O
authors.initials: O
authors.lastname: Sjövall
authors.forename: R
authors.initials: R
authors.lastname: Tahvonen
mesh_terms: D004041:Dietary Fats / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D007536:Isomerism; D013058:Mass Spectrometry; D008970:Molecular Weight; D014280:Triglycerides / Q000032:analysis* / Q000737:chemistry*
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids; D014280:Triglycerides