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Keywords:

  • Flaxseed oil;
  • Gas chromatography-olfactometry (GC-O);
  • HS-SPME;
  • Key odorants;
  • Odor-specific magnitude estimation (OSME)

Summary

Flaxseed oil (FSO) has a distinct flavor among various types of vegetable oil. However, molecular information on FSO volatiles remains limited. In this study, a total of 60 compounds of FSO pressed from three main cultivars in Xinjiang, China, were tentatively identified and then semi-quantified by the headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technique. Thirty of them were previously unknown as volatiles in FSO. These compounds could be categorized into eight groups (with the total numbers and numbers of new compounds per group between brackets): aldehydes (20; 10), ketones (7; 4), alcohols (13; 6), carboxylic acids (8; 3), esters (3; 1), alkanes (3; 3), heterocyclic compounds (4; 2), and other compounds (2; 1). Odor-specific magnitude estimation (OSME) analysis revealed 53 aroma active compounds in three kinds of FSO in a consensus by using GC-O, of which (E, E)-2,4-pentadienal (green, oily), (E, E)-2,4-heptadienal (sweet, hazelnut, woody), 5-ethyldihydro-2(3H)-furanone (cereal-like), 1-hexanol (herbaceous, woody, green), acetic acid (sour, pungent, strong), and butyrolactone (sweet, caramel), perceived with high intensity (3.0, OSME values), and are therefore considered as major contributors to the characteristic FSO odor in Xinjiang, China.

Practical applications: Volatile compounds, whether major or minor, are crucial to FSO quality. Some of them make no direct contribution to the aroma, could be of important help to understand the formation and degradation of the volatiles with significant contribution to aroma, and they may additionally provide useful quality markers. The flavor of FSO varies widely, depending on fruit variety, degree of fruit ripeness, environmental conditions, growing region, and techniques of processing and storage. Therefore, the present study might be useful to identify purity or blending of FSO and may provide information for the producing conditions and the origin of the basic raw material.