Non‐conjugated cis/trans 18:2 in Beef Fat are Mainly Δ‐9 Desaturation Products of trans‐18:1 Isomers

Abstract

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.

The reduction of starch in finishing diets supplemented with oil does not prevent the accumulation of trans-10 18:1 in lamb meat1

“…This confirms an association between high-starch diets and production of these specific CLA isomers (Alfaia et al, 2009). Moreover, significant amounts of nonconjugated 18:2 isomers were identified in LM and s.c. fat for all treatments, and some of them, such as c-9,t-12-18:2 and c-9,t-13-18:2, were recently found to be products of SCD activity (Vahmani et al, 2016).…”

Effects of feeding steers extruded flaxseed on its own before hay or mixed with hay on animal performance, carcass quality, and meat and hamburger fatty acid composition

“…For conjugated linoleic acid (CLA) isomers, the UC-59M standard from Nu-Chek Prep was used which contains all four positional CLA isomers. Trans-18:1 CLA isomers and other BH intermediates not included in the standard mixtures were identified by their retention times and elution orders as reported in literature (Cruz-Hernandez et al, 2004;Gómez-Cortés, Bach, Luna, Juárez, & de la Fuente, 2009;Kramer et al, 2008) and this included recently identified Δ-9 desaturation products of t18:1 isomers (Vahmani, Rolland, Gzyl, & Dugan, 2016). The FAME were quantified using chromatographic peak area and internal standard based calculations.…”

The Growth‐Inhibiting Effects of Beef Fatty Acids on MCF‐7 Cells Are Influenced Mostly by the Depot Location and Inconsistently by the Biohydrogenation Intermediate Content

“…RA, c9,t12‐18:2, c9,t13/c9,t14‐18:2, c9,t15‐18:2) found in the cell PL might have originated from Δ‐9 desaturation of t‐18:1 isomers (e.g. VCA, t12/t13/t14‐18:1, and t15‐18:1) present in the beef fatty‐acid treatments (Vahmani et al, ). However, the exact contribution of Δ‐9 desaturation to these fatty acids cannot be determined in the present study, as both substrates (e.g.…”

“…Hydrogen was used as the carrier gas (1 mL/min initial flow rate, head pressure 25 psi) and the injection port was set at 250 C, while the detector was set at 260 C. The temperature program was as follows: initial temperature at 45 C for 4 min, raised to 175 C at 13 C/min, and held for 27 min, then to 215 C at 4.0 C/min, and finally held at this temperature for 35 min (Kramer et al, 2008). Individual peaks were identified using reference standards (GLC-601 and UC-59 M, Nu-ChekPrep.Inc., Elysian, MN, USA) and according to the peak order and retention times reported in the literature (Cruz-Hernandez et al, 2004;Juarez et al, 2011;Kramer et al, 2008;Vahmani et al, 2016b).…”