DSC isothermal and non-isothermal assessment of thermo-oxidative stability of different cultivars of Camelina sativa L. seed oils

There is growing interest worldwide in the use of camelina oil for food as well as for biofuel purposes. For both of these applications, oxidative stability is an important feature of the oil. Therefore, the aim of this study was to test the thermal resistance to oxidation of three different cultivars of camelina oil i.e., Omega, Luna and Śmiłowska by means of isothermal and non-isothermal differential scanning calorimetry (DSC) oxidation measurement. For isothermal DSC analysis, different temperatures were tested (120, 140, 160 °C) and in the non-isothermal mode different scanning rates (1, 2, 5, 10, 15 °C min−1) were used. To support the DSC data, chemical analyzes were also performed i.e., fatty acid composition, peroxide value, p-anisidine value, acid value and radical scavenging activity by 2,2-diphenyl-1-picrylhydrazyl (RSA DPPH). The isothermal test indicated that for all camelina oils the oxidation induction time (OIT) decreased with an increase in temperature on average from 69.83 min for 120 °C to 5.13 min for 160 °C. The OIT values corresponded very well with non-isothermal DSC results, for which the onset temperatures (Ton) increased with the increase of heating rate on average from 142.15 °C for 1 °C min−1 to 185.75 °C for 15 °C min−1. The parameters of DSC oxidative stability i.e., OIT as well as Ton values were negatively correlated with some unsaturated fatty acids content e.g., α-linolenic acid (C18:3, n-3) and positively with yellowness b* and RSA DPPH. Oil from camelina seeds of Śmiłowska cultivar, which was characterized by the lowest content of α-linolenic acid and the highest b* value of color and RSA DPPH, was the most thermally stable oil.