Uncovering aroma boundary compositions of barley malts by untargeted and targeted flavoromics with HS-SPME-GC-MS/olfactometry

In this study, HS-SPME/GC-MS based untargeted and targeted flavoromics combing with olfactometry were employed to uncover aroma boundary compositions of five types of commercial barley malts with a wide range of Lovibond (L), including kilned base malts (1.8 L and 3.5 L) and roasted caramel malts (10 L, 60 L, and 120 L). Thirty-two compounds were identified as aroma-active with modified detection frequency (MF) > 50%. 3-Methylbutanal (malty), (2E)-nonenal (fatty, cardboard-like), and 2-furfural (burnt, bready) were recognized as the most influential odorants with MF > 70% in all the malts. After untargeted flavoromics, twenty-eight aromas were retained and quantitated. Furthermore, aroma boundary compositions inside/among malt groups were explored with PLS-DA. Eight aroma markers, 3-methylbutanal, 2-isopropyl-5-methyl-2-hexenal, (2E,4E)-Decadienal, 2-furfual, maltol, 2-acetylpyrrole, phenylacetaldehyde, and ethyl hexadecanoate were shortlisted for aroma boundary compositions regarding to the Lovibond of malts.