Enhancement of bioactive compounds in flaxseed (Linum usitatissimum L.) oil through germination during roasting

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Roasting is important for improving the content of bioactive compounds and enhancing the flavor of flaxseed oil. However, the effect of roasting time on germinated flaxseed oil (GFO) is unclear. Herein, the influence of roasting time (0–50 min) at a specific temperature of 160 °C on the physicochemical properties, bioactive compounds, antioxidant capacity, and volatile compounds of GFO from three flaxseed varieties was examined. An extension in roasting time increased the a ⁎ value of GFO, while the L ⁎ and b ⁎ values of GFO decreased. Higher chlorophylls (1.63 ± 0.01–2.18 ± 0.01 mg/kg), carotenoids (2.25 ± 0.00–2.69 ± 0.02 mg/kg), total phenolic content (156.75 ± 2.93–200.03 ± 6.29 mg GAE/kg), phytosterol (1801.93 ± 30.64–1965.23 ± 13.71 mg GAE/kg) and DPPH (320.11 ± 18.22–432.19 ± 14.95 μmol TE/kg) and ABTS radical scavenging activity (810.68 ± 16.29–1119.01 ± 14.25 μmol TE/kg) were detected in GFO after roasting for 20–30 min. However, the total tocopherol and unsaturated fatty acid content declined, and the composition of fatty acids changed insignificantly ( P > 0.05). GC–MS recognized 68 volatile compounds in GFO, in which pyrazine imparted a nutty flavor to the GFO. This study provides important information for the development of high-quality GFO.