Comparison of volatile compounds of hot-pressed, cold-pressed and solvent-extracted flaxseed oils analyzed by SPME-GC/MS combined with electronic nose: Major volatiles can be used asmarkers to distinguish differently processed oils

Analysis of volatile profiles from differently processed flaxseed oils (FSO) was performed by SPME-GC-MS, electronic nose (E-nose) and descriptive sensory analysis. A total of 61 volatiles were tentatively identified and then quantified. Among these components, 51 volatiles were obtained from the hot-pressed FSO, 47 from cold-pressed FSO, and 40 by solvent extraction. Principal component analysis (PCA) demonstrated that three FSO samples tested resulted in significant differences of three treatments (p<0.05) and the marker compounds that contributed to discrimination of different processed FSO were hexanal, (E, E)-2, 4-pentadienal, (E, E)-2, 4-heptadienal, 6-hydroxy-2-hexanone, 1-hexanol, methyl-pyrazine, nonanal, 2,3-pentanedione, 1-butanol, acetic acid, hexanoic acid, and ethyl acetate. In addition, there was good consistency among GS-MS, sensory evaluation and E-nose analysis results. These results indicated that the process method has a significant effect on the aroma quality of FSO and may be helpful in evaluating aroma quality and the detection of frauds. Practical applications: The results showed that the major volatile components could be used as chemical markers to distinguish differently processed FSOs by the chemometric method. There was good consistency among GS-MS, sensory evaluation and E-nose analysis results, suggesting that E-nose technique combined with a PCA of the data provided by the sensor arrays has the good potential to evaluate FSO quality and the detection of frauds.