Changes in volatile compound profiles of cold-pressed berry seed oils induced by roasting

Abstract

This study aimed to compare the volatile compounds of cold-pressed oils obtained from unroasted and roasted chokeberry, raspberry, blackcurrant, and strawberry seeds using comprehensive gas chromatography–mass spectrometry coupled to time of flight mass spectrometry (GC × GC-ToFMS). It is found that the seed type used and chemical composition affected the final aroma of berry oils. The volatile profiles of all berry oils from both unroasted and roasted seeds were dominated by nonheterocyclic chemical class (89% of the total volatiles) with esters predominant (32% of total nonheterocyclic compounds). Unroasted raspberry and blackcurrant cold-pressed seed oils had a less complex volatile profile, and showed similarities between them and differences to chokeberry and strawberry seed oils. Chokeberry seed oil was characterized by the highest levels in ethyl propanoate, methylbutyl acetate, benzaldehyde, (E,E)-2,4-decadienal, acetoin, 3-penten-2-one, benzyl alcohol and strawberry seed oil by methyl acetate, isobutyl acetate, methyl 2-methylbutanoate, ethyl 2-hydroxypropanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, (E,E)-2,4-heptadienal, 1-penten-3-one, and 3,7-dimethyl-1,6-octadien-3-ol. N-containing and furanic-containing compounds contributed about 5% and 4%–16%, respectively, of total amount of volatiles after seed roasting. Roasting was critical for increasing the concentration of compounds derived from lipid peroxidation, especially in blackcurrant seed oils. Profiling volatiles using SPME-GC × GC-ToFMS might be helpful in evaluating oils quality.