Comparison of the oxidative stability of linseed (Linum usitatissimum L.) oil by pressure differential scanning calorimetry and Rancimat measurements

Abstract

The aim of this study was to compare the oxidative stability of linseed oil using the pressure differential scanning calorimetry (PDSC) and Rancimat methods, and to determine the kinetic parameters of linseed oil oxidation. Five cold pressed linseed oils were oxidized at different temperatures under PDSC (90-140 °C) and Rancimat (70-140 °C) test conditions. The oxidative stability of the linseed oils was calculated based on induction times (PDSCτ, Rancimat τ), the Arrhenius equation and activated complex theory, frequency factors (), the reaction rate coefficient () for all temperatures, activation energies (), numbers, activation enthalpies (∆), and activation entropies (∆). The PDSC method was more convenient for the determination of the induction time of linseed oils than the Rancimat method. During oxidation measurement by Rancimat method, the linseed oil polymerized, which affected the measurements. The reaction rate coefficient increased with rising temperature during measurement by both methods. The activation energy values of linseed oil oxidation using the PDSC and Rancimat methods ranged from 93.14 to 94.53 and 74.03 to 77.76 kJ mol, respectively. The , ∆, and ∆ values for the analyzed linseed oils were between 2.11-2.13, 90.54-91.30 kJ mol, -33.20 to -30.90 J mol K calculated by PDSC measurements, and 2.23-2.32, 71.03-74.76, -59.42 to -49.08 J mol K by Rancimat measurements, respectively.

Oxidative stability and the chemical composition of market cold‐pressed linseed oil

“…The examined cold‐pressed linseed oils were characterised by significantly different maximum induction times, expressed as τ max ranging between 56.48 and 125.05 min. Similar results (104.2–115.51 min) but for fresh cold‐pressed oils were presented by Symoniuk et al . In the context of the literature, linseed oils had low oxidative stability.…”

“…However, in this study, no such relation was reported, and the highest correlation was obtained for the linear model. Differences between Rancimat and PDSC methods, which may affect the low correlation of oxidation times, have been reported previously . The approaches differ in sample preparation.…”

Quality Characterization and Oxidative Stability of Camellia Seed Oils Produced with Different Roasting Temperatures

“…In a previous study, Ea values of between 74.03 77.76 kJ/mol were obtained for linseed oil 34 . The Ea values of roasted and unroasted argan oil, meanwhile, were 90.71 and 94.12 because these oils have high levels of β-carotene and the other compounds, such as phospholipids and phosphorus, that improve resistance to lipid oxidation 9 .…”

1H LF‐NMR Energy Relaxation Time Characterization of the Chemical and Morphological Structure of PUFA‐Rich Linseed Oil During Oxidation With and Without Antioxidants

“…Maryland, USA) was used. The levels of secondary oxidation products were evaluated by p ‐anisidine values test according to the AOCS Official Method Cd 18‐90 (2002) …”

“…However, hydroperoxides usually undergo further decomposition as oxidation advances and the PV test does not give a real measure of the degree of oxidation or the oxidative stage . Another common test is based on the p ‐ansidine value test that provides an estimation of the level of the aldehyde products in the tested sample …”