Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 degrees C/min) as well as oxidative induction time (OIT) isothermally at 120 degrees C and 140 degrees C, and oxidation onset temperatures (Ton) at 2 and 5 degrees C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 degrees C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 degrees C/min, while for 5 degrees C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

Automated summary

This study aimed to describe the thermal properties of selected cultivars of flaxseed oil using the DSC technique. Findings revealed characteristics of crystallization and melting profiles, as well as the influence of temperature and heating rate on the stability of flaxseed oil during thermal oxidation. Negative correlations were observed between unsaturated fatty acid content and thermal properties.