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

Abstract

Oxidative stability and minor components of market linseed oils were evaluated. The oils were investigated for their primary and secondary oxidation products, fatty acid composition and pigment content, and samples were also examined for their scavenging of 1, 1‐ diphenyl‐2‐picrylhydrazyl (DPPH) and total phenolic content. Rancimat and pressure differential scanning calorimetry were used to assess oxidative stability. The analysed oils were of good quality, meeting the requirements of the Codex Alimentarius standard. Linseed oils were characterised by 45–65% content of α‐linolenic acid. The TEAC equivalent of linseed oils ranged from 1.25 to 1.42 mM of Trolox kg−1 oil, and FAE ranged from 60.25 to 115.12 mg of ferulic acid 100 g−1 oil. The correlation between linseed oil oxidative stability as measured by the Rancimat and PDSC methods was low (r = 0.55). Based on the obtained results of oxidative stability and the content of chemical compounds, principal components analysis was conducted. PCA indicated that none of the chemical compounds correlated strongly with the oxidative stability of linseed oils as determined by the Rancimat method. However, in the case of the PDSC method, the content of primary and secondary products of oxidation had the strongest impact on the oxidative stability of linseed oils. The correlation coefficients describing the impact of different chemical compounds on induction time using the Rancimat and PDSC tests were between −0.43 to 0.45 and −0.82 to 0.72, respectively. Practical applications: The results show that linseed oils available on the market were of differing but good quality. Results of oxidative stability tests demonstrate that Rancimat and pressure differential scanning calorimetry (PDSC) methods should not be used interchangeably for assessing linseed oil oxidative stability (r = 0.55). The initial degree of oxidation had the greatest impact on the oxidative stability of linseed oil, but none of the measured quality parameters showed a high correlation with the Rancimat induction time. Principal component analysis verified the designated correlations between induction times in the Rancimat and PDSC tests and quality features. PCA also confirmed differences between the examined linseed oils. Market linseed oils are examined to their oxidative stability using Rancimat and pressure differential scanning calorimetry, and their chemical composition. The influence of selected discriminants on the oxidative stability of linseed oil is determined.

Bioactive Compounds, Nutritional Quality and Oxidative Stability of Cold-Pressed Camelina (Camelina sativa L.) Oils

“…Samples of tested oils were prepared for the GC-flame ionization detector (FID) analysis as fatty acid methyl esters according to the AOCS Official Method Ce 2-66 [28]. Determination of esterified fatty acids in camelina oils was performed according to the AOAC Official Method 996.06 [29] with modifications described by Symoniuk et al [30]. Methyl esters were separated on a TRACE 1300 (Thermo Fisher Scientific, Inc., Wilmington, DE, USA) gas chromatograph equipped with a Restek BPX70 GC capillary column (60 m in length × 0.22 mm I.D., 0.25 µm film thickness).…”

Evaluation of the Oxidative Stability of Cold‐Pressed Rapeseed Oil by Rancimat and Pressure Differential Scanning Calorimetry Measurements

“…Table 5 presents the correlations between individual quality factors and oxidative stability determined using the Rancimat and PDSC methods. [43] The greatest influence on the stability of the linseed oil had a PV value (r ¼ À0.82), Totox indicator (r ¼ À0.82), and FAE (r ¼ 0.60). As it appears from the obtained results, the content of primary oxidation products and the initial level of oxidation (Totox indicator) of the oil were the strongest correlated with induction www.advancedsciencenews.com www.ejlst.com time determined using Rancimat and PDSC method.…”

“…[41,42] Our earlier studies focused on the correlation of stability of different cold-pressed oils and showed a very low dependence between induction time determined using Rancimat and PDSC method for linseed oil (r ¼ 0.55) [43] and different cold-pressed oils (r ¼ 0.66). These studies mainly concerned the comparison of the stability of refined oils where high values of the correlation coefficient were obtained (r > 0.90).…”

“…These studies mainly concerned the comparison of the stability of refined oils where high values of the correlation coefficient were obtained (r > 0.90). [43] Moreover, Rancimat oxidation curve does not have a course with a sudden increase in conductivity, what might also affect the result designated automatically. [30] Differences in the correlation coefficient between both methods may be due to different oil fatty acid composition.…”

Investigation of stability of cold pressed linseed (Linum usitatissimum L.) oil

“…Linseed contains about 36-40% oil which is a rich source of polyunsaturated fatty acid, phytosterols, phospholipids, and vitamins (Popa et al, 2012;Rudnik et al, 2001). The dominant fatty acid in linseed oil is α-linolenic acid and its content is more than 40% (Michotte et al, 2011;Symoniuk et al, 2017). The αlinolenic acid is a ω-3 and essential fatty acid and it is reported that the higher intake of it can decrease the production of proinflammatory molecules and consequently the risk of cardiovascular diseases and cancer is reduced (Hasiewicz-Derkacz et al, 2015).…”