# Comparison of the Chemical and Sensorial Evaluation of Dark Chocolate Bars
## 3 Results and Discussion
### Headspace Compositions
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Compounds** & **Lri.1** & & & & & & & & & & & & & & & & \\ \hline Monoterpene hydrocarbons & 0.7 & - & 1.7 & - & - & 0.2 & 2.2 & - & 0.9 & - & - & 1.2 & 3.2 & 0.3 \\ Oxygenated monoterpenes & 2.4 & 1.7 & 0.2 & - & 2.1 & - & 1.3 & 0.3 & 4.0 & 0.7 & - & 2.1 & 0.4 & - \\ Sesquiiterpene hydrocarbons & 0.2 & 0.2 & 0.6 & - & 0.3 & - & 0.6 & 0.1 & 0.2 & 0.1 & 0.2 & - & 1.8 & 0.2 \\ Oxygenated sesquiterpenes & - & - & - & 28.8 & - & - & - & - & 0.3 & - & - & - & - & - \\ Pyrazines & 71.2 & 69.1 & 65.9 & 31.2 & 77.0 & 81.4 & 70.7 & 76.0 & 78.1 & 88.9 & 83.9 & 47.1 & 31.5 & 67.0 \\ Pyrrides & 1.8 & - & 4.7 & 1.1 & 2.3 & - & 2.9 & 1.6 & 1.7 & - & - & 0.9 & - & 0.8 \\ Arocontaneids & 0.4 & 0.2 & 1.8 & 4.7 & 1.0 & - & 0.2 & 0.4 & 0.3 & - & 0.2 & 0.2 & 2.1 & - \\ Phenylpropanols & - & - & - & - & - & - & - & 0.1 & 0.2 & 0.9 & 2.6 & 1.6 & 6.9 & 0.3 \\ Non-terpene acids & 4.1 & 2.5 & 4.9 & 3.1 & 0.4 & 0.6 & 0.4 & 1.2 & 2.4 & 0.7 & 0.9 & 5.4 & - & 3.7 \\ Non-terpene alcohols & 8.5 & 6.3 & 4.8 & 3.4 & 3.4 & 3.6 & 4.4 & 2.4 & 1.4 & 1.8 & 3.6 & 6.2 & 7.6 & 6.7 \\ Non-terpene aldehydes & 2.0 & 2.9 & 6.0 & 18.1 & 5.3 & 0.8 & 5.9 & 6.4 & 1.8 & 0.4 & 0.2 & 13.8 & 9.7 & 7.2 \\ Non-terpene esters & 8.3 & 16.3 & 8.8 & 2.8 & 2.6 & 10.0 & 7.1 & 11.6 & 8.7 & 6.6 & 8.0 & 21.6 & 36.8 & 13.9 \\ Non-terpene ketones & 0.0 & 0.8 & - & 6.3 & - & - & - & - & - & 0.4 & - & - & - \\ Non-terpene hydrocarbons & 0.5 & - & 0.5 & - & 5.0 & 2.5 & 0.5 & - & 0.1 & - & - & 0.2 & - & - \\ Total identified (\%) & 100.0 & 100.0 & 99.9 & 99.5 & 99.4 & 99.1 & 100.0 & 100.0 & 100.0 & 100.0 & 100.0 & 100.0 & 100.0 \\ \hline \hline \end{tabular}  
* Linear retention indices on a DB5 capillary column. 2 Not detected. Legend of the sample names: the SM code stands for supermarket, followed by a unique number, each identifying one specific commercial sample among this type.  
\end{table} 
Table 4: _Cont._most detected aldehydes, whose highest relative concentration was registered in sample HD1; it is listed among the undesirable notes, as it is pungent and bitter [11; 12; 14; 15]. Non-terpene alcohols, another typical chemical class of VOCs found in chocolate headspace, were identified in relevant relative concentrations in all samples (HD: 1.9-10.6%; BIO: 2.7-4.2%; SM: 1.4-8.5%). Among them, phenylethylalcohol and 2,3-butanediol were the most represented. Non-terpene alcohol presence is commonly reported as a desirable attribute of chocolate aroma, as they are responsible for pleasant flowers [1; 4; 9; 11] and sweet [11] notes. Among those detected in the present study, 2,3-butanediol, whose highest relative abundances were identified in samples SM12 and 14, and HD3, 5, and 7, confer cocoa butter aroma notes [4; 14; 30]. Phenylethyl alcohol is reported as a pleasant odor in chocolate samples, reminiscent of honey [11]: its highest relative quantities were found in samples SM13 and HD2. Dodecanol, whose presence was detected only in sample HD2, is described as a delicate floral note when diluted, but it turns into an unpleasant aroma when present in significant content [29]. Among non-terpene compounds, acids were also detected in almost all samples (HD: 0.8-5.2%; BIO: 2.1-3.5%; SM: 0.4-5.4%), with only two exceptions (HD5 and SM13). Of this class, nonanoic and isovaleric acid were the two most represented in all HSs. (_E_)-Anethole was the most represented detected phenylopropanol compound, varying between samples in which it was not detected at all, to headspace in which its presence was quantitatively relevant (6.2% in HD3; 6.9% in SM13). In HD HSs, relative terpene concentrations over 5% were only found for HD2 and HD8; in the former, monoterpeak hydrocarbons, only represented by limonene, were up to 7.2%, while in the latter sesquiterpene hydrocarbons prevailed, with \(\beta\)-patchoulene as the most represented.