Variation in Linseed Oil Composition: Impact of Cultivar, Cultivation System, and Year of Cultivation.

Linseed oil quality depends on cultivar and agriculture practice/conditions. In this study, we analyzed the effect of the main variable, which was continuous cropping system vs. crop rotation system. The aim of this study was to compare the oil content and composition (fatty acid composition and sterol, tocochromanol, carotenoid, and phenolic contents) of two fiber-type linseed cultivars (Modran and Nike). All measurements were performed according to standard chromatographic/spectrophotometric procedures typical for oil analysis. The factors that affected the crop yield and oil quality of the tested cultivars included the cultivation system (crop rotation or continuous cropping), plant protection level (herbicide application or no herbicide application), and year of cultivation (2018 and 2019). The cultivars exhibited high oil content (35.4-42.7%) with substantial omega-3 fatty acid (α-linolenic acid) content (53.6-62.2% of total fatty acids). The primary bioactive components in all the oils were sterols (dominated by β-sitosterol), with their content reaching 5079 mg/kg, and tocochromanols, with their content reaching 679 mg/kg (dominated by γ-tocopherol), which was influenced by all of the studied factors. In contrast, carotenoids and phenolic compounds constituted a smaller fraction of the oils (up to 17 and 159 mg/kg, respectively), but their content was the most variable and was strongly dependent on the cultivation year and cultivation system (CV 21 and 37%, respectively). In summary, the results of the current study showed that continuous linseed cropping resulted in increased levels of carotenoids, phenolic compounds, and γ-tocopherol in oil. Our findings indicated that the oil content was mostly affected by the cultivar and cultivation year, while the α-linolenic acid content in the oil was also affected by plant protection practices. These findings may be helpful in predicting the composition of obtained linseed oil and applying proper cultivation technology, depending on the purpose of oil usage.