## 3 Results and Discussion
### Volatile Composition of Single-Dose Espresso Coffee-Based Blends
\begin{table}
\begin{tabular}{c c c c c} \hline
**Compound** & **CAS Number** & **Reported \({}^{*}\)** & **Aroma Descriptor \({}^{b}\)** & **References \({}^{c}\)** \\ \hline _Aromatics_ & & & & \\ \hline Methylbenzene & 108-88-3 & [33] & Sweet-gassy & [34] \\ Ethylbenzene & 100-41-4 & [33] & Sweet-gassy & [34] \\
1,3-Dimethylbenzene & 108-38-3 & [33] & - & \\ Phenylethylhene & 100-42-5 & [33] & Sweet-gassy, baslamic, floral & [34,36] \\
1-Methyl ethylbenzene & 98-82-8 & & - \\
1-Ethyl-4-methylbenzene & 622-96-8 & [33] & - \\
1-2,3-Trimethylbenzene & 526-73-8 & & - \\
1-Methyl-3-propylbenzene & 1074-43-7 & & - \\ Butylbenzene & 104-51-8 & & - \\
4-Ethyl-1,2-dimethylbenzene & 934-80-5 & & - \\
1-Ethyl-2,3-dimethylbenzene & 933-82-3 & & - \\
1,2,4,5-Tetramethylbenzene & 95-93-2 & [33] & - \\
1,2,3,4-Tetramethylbenzene & 488-23-3 & [61] & - \\ Pentylbenzene & 538-68-1 & & - \\
1-Butylphenylbenzene & 4537-15-9 & & - \\ \hline \end{tabular}
\begin{tabular}{c} _Aliphatics_ \\ \hline
2-Propanone & 67-64-1 & [33] & Ehhereal, lemon & [34,41] \\
2-Butanone & 78-93-3 & [33] & Ehhereal, sweet apriot-like & [34,36] \\
2-Butanedone (Daacetyl) & 431-03-8 & [33] & Buttery & [34,36,44,46] \\
2-Perntanone & 107-67-9 & [33] & Ehhereal-fruity, wine & [34,36] \\
2-Sentanedone & 600-14-6 & [33] & Buttery, oily, sweet, caramel-like, milky & [2,20,34,37,44] \\
1-Hydrooxy-2-propanone & 116-09-6 & [33] & Sweet-caramel-like, mushroom, earthly, nutty & [20,34,37,38] \\
4-Methyl-2-pentanone & 108-10-1 & [33] & Ehhereal-fruity, spicy & [34,36] \\
3-Pentent-2-one & 625-32- & [33] & Friuity & [36] \\
3-Hydroxy-2-Butanone (Acotin) & 513-86-0 & [33] & Creamy-fatty-buttery, woody, yogurt & [20,34,36,41] \\
2-Methyl-1-penten-3-one & 2504-01-3 & - & - \\
2,4-Pentanedone & 123-54-6 & [33] & Ehhereal-mity, metallic & [34] \\
3-Hexanone & 589-38-8 & [33] & Ehhereal, grape, wine-like & [37] \\
2-4-Dimethyl-3-pentanone & 565-80-0 & [33] & - & \\
2-Hexanone & 591-78-6 & [33] & - & \\
3-4-Hexanedone & 4437-51-8 & [33] & Buttery, toasty, burnt, nutty, caramel-eggy & [34,36] \\
1-Hydrooxy-2-butanone & 5072-67-8 & [33] & Tonsed & [20] \\
3-Hydroxy-2-pentanone & 3142-66-3 & [33] & Earthly, aged & [37] \\
2-Hydroxy-3-guenenenen & 5704-20-1 & [33] & - & \\
3-Hexen-2-one & 763-93-9 & - & - \\
3-Hexen-2,5-dione & 4436-75-3 & - & - \\
4-Methyl-2-hexanone & 105-42-0 & - & - \\
4-Heptanone & 123-19-3 & [33] & Ehhereal-fruity, pineapple-like, strawberry-like & [34] \\
1-Acetyloxy)-2-propanone & 592-20-1 & [33] & Friuity-buttery, sour & [34] \\
3-Heptanone & 106-35-4 & [33] & Green, fatty, fruity, sweet, ethereal & [34,36] \\
2-Heptanone & 110-43-0 & [33] & Friuity, spicy, cinnamon, banana, spicy & [36] \\
3-Hepten2-one & 119-44-4 & [37] & Green-grass & [36] \\
2,5-Hexanedone & 110-13-4 & [33] & Sweet-ethereal & [34] \\
6-Methyl-3-heptanone & 624-42-0 & - & - \\
6-Methyl-2-heptanone & 928-67- & - & - \\
5-Methyl-2-heptanone & 18217-12-4 & - & - \\
1-Octen-3-one & 4312-99-6 & [33] & Mushroom & [36,38,45,62] \\
2-3,0-Octanedione & 585-25-1 & [33] & Warmed-over & [36] \\
6-Methyl-5-hepten-2-one & 110-93-0 & [33] & Strong, fatty, green, citrus-like & [36] \\
2-Octanone & 111-13-7 & [33] & Floral, bitter-green, musuly-herbaceous, & [34,36] \\  & & urnipe-apple fruity & [34,36] \\
3-Octen-2-one & 1660-44-9 & [33] & Friuity, lemon & [36] \\
2-Nonanone & 821-55-6 & [33] & Friuity-foral, fatty, archaeous, rue & [36,60] \\
3-Nonen-2-one & 14309-57-0 & & Friuity & [36] \\ \hline _Cyclic_ & & & & \\ \hline
2-Cyclopenten-1-one & 930-30-3 & [33] & - & \\ Cyclohexane & 108-94-1 & Peppermit, acetone-like & [36] \\
4-Cyclopentene-1-3 dine & 930-60-9 & [20,63] & - & \\
2-Methyl-2-cyclopenten-1-one & 1120-73-6 & [33] & - & \\
2-Cyclohexene-1-one & 930-68-7 & [33] & Gassy-mint & [34] \\
5-Ethylylylcopent-2-en-1-one & 3409-63-8 & - & - \\
6-Methylenedicycled(3.2.0]hept-3-en-2-once & - & - & - \\
3-Methyl-2-cyclopenten-1-one & 1193-18-6 & [33] & Caramel-like, phenolic, mild cherry & [36,60] \\
2-2,6-Trimethylcyclohexanone & 2408-37-9 & - & - \\
3-Cyclohexene-1-4-dione & 4505-38-8 & - & - \\
3-5-Dimethyl-2-cyclohex-1-one & 1123-09-7 & - & - \\ \hline
2-Hydroxy-3-methyl-2-cyclopenten-1-one & 80-71-7 & [33] & Sweet, caramel-like-spicy, wahunt, mugle, licorice, & [34,35,52] \\
2,3,4-Trimethyl-2-cyclopenten-1-one & 28790-86-5 & [29] & - \\
3,5-Dimethyl-1,2-cyclopentanedone & 13494-07-0 & [33] & - \\
3-Ethyl-2-hydroxy-2-cyclopenten-1-one & 21835-01-8 & [33] & Caramel-like, sweet, sugary & [36,60] \\ \hline \end{tabular}
\end{table}