A versatile method to fingerprint and compare the oxidative behaviour of lipids beyond their oxidative stability

Abstract

In this work we propose the use of isothermal thermogravimetry to evaluate the oxidative stability of a lipid and to evaluate how the glyceride composition affects the entire oxidative process, to quantify the oxidation undertaken by the lipid, and numerically compare the oxidative behaviour of different lipids. The innovative aspect of the present method lies in the acquisition of a prolonged “oxygen uptake” curve (4000–10,000 min) of a lipid under oxygen and in the development of a semi-empirical fitting equation for the experimental data. This provides the induction period (oxidative stability), and allows to evaluate the rate of oxidation, the rate and the magnitude of oxidative degradation, the overall mass loss and the mass of oxygen taken by the lipid upon time. The proposed approach is used to characterize the oxidation of different edible oils with different degrees of unsaturation (linseed oil, sunflower oil, and olive oil) as well as chemically simpler compounds used in the literature to model the autoxidation of vegetable oils and lipids in general: triglycerides (glyceryl trilinolenate, glyceryl trilinoleate and glyceryl trioleate) and methyl esters (methyl linoleate and methyl linolenate). The approach proves very robust and very sensitive to changes in the sample composition.

Synthetic urushiols from biorenewable carbon resources: chemical conversion of enzymatic degradation products of wood lignin to an ancient yet future coating material

“…The similar curing profile was observed with an urushiol analog synthesized from vanillyl alcohol, 20 suggesting a slightly different initial reaction step for an artificial urushi prepared from synthetically pure urushiol analogs, compared to the one prepared from natural urushiols, which are a mixture of catechols bearing different side chains. The initial slow curing reaction resembles the auto-oxidation profile of vegetable oils, 40 suggesting that a similar auto-oxidation of trienyl side chains takes place from the initial stage. In addition, the lower value of hardness obtained from Cambodian thitsiol bearing mainly dienyl side chains suggests that the number of unsaturated bonds in the side chain has a much stronger influence on the hardening process compared to the substituent position to the catechol core (Fig.…”

Antioxidative effects of alkyl esters of sinapic acid on flaxseed oil and its fatty acid methyl esters

“…The researchers attributed this to the occurrence of inhibitory reactions between sesamol and LOO•, or to the reduction of pro-oxidative reactions between LOOH-LH and sesamol. We interpreted the low activities of sinapic acid conjugates in FAME relative to oil with the approach of Pizzimenti et al (2023), as they explained this situation by taking into account the differences in chemical composition between oils and corresponding acylglycerols. FAME molecules have higher molecular mobility and diffusion rate, which means methyl esters react much faster and take up more oxygen.…”