Human liver cells (HepG2) were cultured with individual trans (t) 18:1 including t6-, t12-, t13-, t14-, t15- and t16-18:1, and retention times of their Δ-9 desaturation products were determined using 100-m biscyanopropyl-polysiloxane and SLB-IL111 columns. Corresponding peaks were found in beef adipose tissues known to have different delta-9 desaturase activities. Further lines of evidence indicating the presence of Δ-9 desaturation products of t-18:1 isomers in beef fat were developed by analysis of fatty acid methyl esters (FAME) fractionated using Ag+-TLC, and by GC/MS. Some of the Δ-9 desaturation products of t-18:1 have been previously identified in ruminant fat (c9, t12- and c9, t13-18:2). Some of the Δ-9 desaturation products of t-18:1 (c9, t14- and c9, t15-18:2) have been previously tentatively identified as different fatty acids, and for the first time we provide evidence of the presence of c9, t16-18:2, and where t6, c9-18:2 may elute during analysis of FAME from beef fat.
Keywords: Gas chromatography; cis/trans 18:2; trans 18:1; Δ-9 desaturation.