# How Coffee Capsules Affect the Volatilome in Espresso Coffee
## 3 Results and Discussion

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\begin{table}
\begin{tabular}{l l l l l l l l l l l l l l l l l l} \hline \hline \multicolumn{1}{c}{} & \multicolumn{1}{c}{(Ots-A)-Databaseatabase} & \multicolumn{1}{c}{23.5} & \multicolumn{1}{c}{24.5} & \multicolumn{1}{c}{24.5} & \multicolumn{1}{c}{24.5} & \multicolumn{1}{c}{25.5} & \multicolumn{1}{c}{25. Figure 1: Comparison abundance value of common compound between Biologico coffee “with capsule” and “without capsule”. Figure 2: Comparison abundance value of common compound between Deciso coffee “with capsule” and “without capsule”. Figure 4: Comparison abundance value of common compound between Guatema coffee “with capsule” and “without capsule”. Figure 3: Comparison abundance value of common compound between Dolce coffee “with capsule” and “without capsule”. Indeed, over one thousand different chemical entities have been identified in coffee beans; a significant number of these will be extracted during brewing, a comparatively small subset of chemicals impact on the aroma. The coffee aroma intensity is influenced by the compression of the coffee pod, which improves the extraction of the volatile fraction. Indeed, the results show how the coffee obtained by the pods has a more intense volatilome. Studies often consider two main factors when discerning a compounds' aroma impact: the concentration of the compound, and the compound's odor threshold, i.e., the minimum concentration at which we can detect its smell [19]. The ratio of a compound's concentration to its odor threshold gives the compounds an 'odor activity value' (OAV) [20], which gauges its importance to the overall aroma. Several families of compounds are significant contributors to coffee's aroma. Some examples can be families of compounds such as aldehydes, which generally add a fruity and green aroma, furans, which contribute caramel-like odors, and pyrazines, which have an earthly scent. Guaiaicol and related phenolic compounds offer smoky, spicy tones, and pyrroles and thiophenes are also present in low concentrations. A closer look to all the volatile compounds that we found with the GC-MS results, shown in Table 1, explains how several of them were common concerning the four samples with and without capsule. Regarding the first one, there were 29 volatiles in common between the sample with capsule between a total number of 205 total compounds found. In particular:  
* Five of them are aldehydes: 2-methyl- Butanal; 5-methyl-2-furancarboxaldehyde; 1H-Pyrrole-2-carboxaldehyde; Furfural; and Isocyclocitral. Aldehydes are important molecules because they enrich the volatilome with floral flavors [21]. * Three are pyrazines: methyl-Pyrazine; 2,6-dimethyl-Pyrazine; 2-methyl-Pyrazine; 3-ethyl-2,5-dimethyl Pyrazine. Pyrazines are compounds formed during cooking processes in food matrices consisting of both a sugar fraction and a protein/amino acid fraction, characterizing the typical toasted notes that are perceived from the food. * Six are of them are alcohols 2-Furanmethodanol; 1-1(H-pyrazol-1-yl)-2-Propanone; 2-Furanmethodanol acetate; 2-Furanmethodanol, propanoate; Maltol; Benzo-2,3-pyrrole. Alcohols can have two functions. They can directly influence the volatilome or indirectly act as precursors of aldehydes and ketones. * Three are furans: 2-Hexanoylfuran; 2,2\({}^{\prime}\)-methylenebis-Furan; 2,2\({}^{\prime}\)-[oxybis(methylene)]bis-Furan. Furan is a colorless chemical with a low molecular weight and highly volatile. It forms as a result of food heating and contributes to the roasted taste in some. The coffee and in particular when roasted, represents a source of allimentary exposure to the furan. * Five are ketones: 1-(2-methyl-1-cyclopenten-1-yl)-Ethanone; 1-(6-Methyl-2-pyrazinyl)-1-ethanoneone; 1-(5-methyl-2-furanyl)-1-Propanone; 1-(2,5-dihydroxyphenyl)-Ethanone; 1-(2,6,6-trimethyl-1,3-cyclohexati-1-yl)-(E)- 2-Buten-1-one. Ketones are important molecules because they enrich the volatilome with floral flavors. * Two are phenols: Phenol; 2-methoxy-Phenol.