Identification of aging markers and volatile compound changes during natural aging of commercial whisky by HS–(SPME)–GC–MS

Aging is a crucial step in whisky making, shaping the final flavor through various chemical transformations. Understanding the molecular changes involved is essential for guiding research on artificial aging. To this extent, the volatile compound profiles of renowned whiskies were established by using solid-phase microextraction combined with gas chromatography–mass spectrometry. Several significant aging time markers were identified independently of whisky characteristics, such as origins, peating intensity, or grain type. These markers included diethyl nonanedioate, ethyl 2-methylbutanoate, and 1,1-diethoxybutane, among others. When peated samples were excluded, additional markers were identified, such as ethyl furan-2-carboxylate. While correlations between acid and ester content were established, the relationship between carboxylic acids and aging time was found to be dependent on the grain composition and fermentation processes.