Effect of Roasting on Fatty Acid Profile of Brown and Yellow Varieties of Flaxseed ( Linum usitatissimum   L)

Purpose: To monitor changes in fatty acid profiles of brown and yellow varieties of flaxseeds in the raw and roasted states using gas chromatography (GC).
Methods: Samples of flaxseeds were extracted with n-hexane in a Soxhlet apparatus for 8 h. Methylesterification of the samples was performed by methanolic boron trifluoride (BF3-MeOH) method according to American Oil Chemists' Society (AOCS). Fatty acid (FA), analyzed using GC equipped with a split/splitless capillary injector and flame ionization detector (FID).
Results: The results indicate that lipid content varied with the type of seed. Seed oil content was 53.31 ± 0.30 and 45.20 ± 0.20 % for roasted and unroasted brown flax, respectively, and 10.25 ± 0.04 % for the yellow type. The yellow and roasted brown type, at 300 °C, showed the lowest and highest oil content, respectively. The highest calculated oxidizability (COX) value was found for the unroasted brown type (13.19 ± 0.01 %) whilst the lowest amount was observed for the roasted brown seed at 350 °C (12.79 ± 0.01 %). COX value for yellow type was 5.62 ± 0.01 %.
Conclusion: This study shows that the fatty acids content of flaxseeds vary with roasting conditions. This is significant because flax seed fatty acid composition influences the applications of the oil.

Keywords
Oil; Flaxseed; Roasting; Fatty acid; Linum usitatissimum; Calculated oxidizability value