A kinetic study of the thermally induced isomerization reactions of 9 c ,12 c linoleic acid triacylglycerol using gas chromatography

Green synthesis and structure characterization of resveratrol conjugated linoleate

To improve the stability and broaden the application of resveratrol (Res), the Res conjugated linoleate (RCL) were synthesized successfully using Res and 9c,11t-conjugated linoleic acid (CLA) with N, N'-carbonyldiimidazole (CDI) as catalyst for the first time. The Res conversion and the yield of RCL were achieved at 96.85% and 65.30%, respectively. In comparison with Res, RCL has lower acid value (1.80 mg/g) and peroxide value (3.25 meq/kg) and higher thermal stability (improved by 115.3 ℃). RCL was identified as a novel triester compound with a physical appearance as a light-yellow viscous oil. The 9c,11t-CLA was activated by CDI first, reacted with Res to form 4'-Res-ester preferentially, followed by 5,4'-Res-ester and 3,5,4'-Res-ester. The transition-state quaternary ring structures of monoesters were the key structures determining the formation of RCL. This study provided an efficient and eco-friendly approach for the synthesis of RCL, promoting the development of the synthesis of Res long-chain fatty acid ester.

New research development on trans fatty acids in food: Biological effects, analytical methods, formation mechanism, and mitigating measures

The trans fatty acids (TFAs) in food are mainly generated from the ruminant animals (meat and milk) and processed oil or oil products. Excessive intake of TFAs (>1% of total energy intake) caused more than 500,000 deaths from coronary heart disease and increased heart disease risk by 21% and mortality by 28% around the world annually, which will be eliminated in industrially-produced trans fat from the global food supply by 2023. Herein, we aim to provide a comprehensive overview of the biological effects, analytical methods, formation and mitigation measures of TFAs in food. Especially, the research progress on the rapid, easy-to-use, and newly validated analytical methods, new formation mechanism, kinetics, possible mitigation mechanism, and new or improved mitigation measures are highlighted. We also offer perspectives on the challenges, opportunities, and new directions for future development, which will contribute to the advances in TFAs research.

Thermally induced isomerization of linoleic acid and α-linolenic acid in Rosa roxburghii Tratt seed oil

Rosa roxburghii seed oil is obtained from the seeds left following pressing of the juice from R. roxburghii fruit. The total oil content of R. roxburghii seed was around 9.30%. The fatty acid profile of the oil was determined by gas chromatography (GC). Among the 11 fatty acids identified in the oil, seven were unsaturated fatty acids (UFAs) (92.6%); four were saturated fatty acids (SFAs) (7.17%). Then, the kinetics of formation of trans-fatty acids was studied by GC. Heat treatment of R. roxburghii seed oil showed an increase in the relative percentage of linoleic acid and α-linolenic acid isomers with increasing temperature and time. The formation of linoleic acid and α-linolenic acid isomers followed a zero-order reaction. The presence of O2 enhanced the isomerization of these UFAs. In addition, the rate constants and activation energies for the geometrical isomerization of UFAs in R. roxburghii seed oil were presented. Overall, R. roxburghii seed oil contains high UFA contents. Heating temperature and duration and the presence of O2 should be considered to reduce the formation of trans-fatty acids during thermal treatment of R. roxburghii seed oil.

Highly selective isomerization of cottonseed oil into conjugated linoleic acid catalyzed by multiwalled carbon nanotube supported ruthenium

Supported ruthenium (Ru) has the capacity to catalyze the conjugation of double bonds in linoleic acid (LA) into conjugated linoleic acids (CLAs). It has been reported that CLAs have shown a lot of benefits to human health. To enhance the selectivity of cottonseed oil (CSO) to CLAs, various Ru catalysts supported by multiwalled carbon nanotubes (Ru/MWCNTs) were prepared using a microwave-heated ethylene glycol method. All catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic efficiency/selectivity of Ru/MWCNTs and two commercially available Ru catalysts (Ru/C and Ru/Al₂O₃) were investigated in a solvent-free system by catalyzing the isomerization of CSO. TEM analysis showed that Ru nanoparticles with average sizes of 1.0 nm to 1.8 nm were uniformly dispersed on the surface of the supports. Among the as-synthesized Ru/MWCNTs, catalyst S1 (diameter < 8 nm, length 0.5–2 μm) and catalyst S4 (diameter < 8 nm, length 10–30 μm) exhibit excellent catalytic performance for isomerization of CSO with high yield of total CLA (15.91% and 11.56%, respectively) and high turnover frequency (TOF) of 10.39 and 11.38 h⁻¹, which is much better than two typical commercial Ru catalysts (Ru/Al₂O₃ and Ru/C). It has been revealed that the average particle size and chemical state of Ru on the surface of MWCNTs have influence on the activity and selectivity of the isomerization reaction.

Ruthenium supported on multiwalled carbon nanotubes is a highly efficient catalyst for the linoleic acid conjugation of cottonseed oil.

Mechanisms of isomerization and oxidation in heated trilinolein by DFT method

In order to investigate the molecular mechanisms of the heat-induced cis/trans isomerization and oxidative cleavage of trilinolein, a highly purified sample was heated at a range of temperatures (120, 140, 160, 180, 200, 220 °C) for 5 h.