# How Coffee Capsules Affect the Volatilome in Espresso Coffee
## 3 Results and Discussion
Phenols are molecules possible to find in the raw material. Generally, polyphenols and chlorogenic acid have higher concentration. * Two acids: Propanoic acid ethyl ester; Furfuryl pentanoate. Carboxylic acids are a part of the non-volatile component of coffee seeds after roasting, generated as a result of complex reactions that occur during roasting. * One alkaloid: Caffeine. This compound is responsible for the bittermess. On the other hand, the results about coffee obtained without capsule, shown in Table 1, highlight a few more common compounds between the four samples, in particular 34:
* Six of them are aldehydes: 2-methyl-Butanal; Furfural; Nonanal; Phenylacetaldehyde; 1-methyl-1H-Pyrrole-2-carboxaldehyde. * Five are pyrazines: methyl-Pyrazine; 2,6-dimethyl-Pyrazine; 3-ethyl-2,5-dimethyl Pyrazine; (1-methylethenyl)-Pyrazine; 3,5-diethyl-2-methyl-) Pyrazine. * Six of them are alcohols: (2-Furanmethodanol; 2-Furanmethodanol acetate; Maltol; 1-(2-furanylmethyl)-1H-Pyrrole; Indole; 5-methyl-1H-Indole. * Three are furans: 2,2\({}^{\prime}\)-methylenebis-Furan; 5-methyl-2-furancarboxaldehyde; N-(2-furfurylyl)-Urea. * Five are ketones: 1-(2-methyl-1-cyclopenten-1-yl)-Ethanone; 1-(5-methyl-2-furanyl)-1-Propanone; 1-(acetyloxy)-2-Propanone; 1-(2-furanyl)-Ethanone; 1-(2-furanyl)-2-Butanone; 1-(1H-pyrrol-2-yl)-) Ethanone. * Five are phenols: Phenol; 2-methoxy- Phenol; 2-methyl-Phenol; 2-methoxy-5-(1-properyl)-, (E)-Phenol; <4-vinyl-> Guaiacol. * Two acids: Furfuryl l pentanoate; Furfuryl propionate. * One Benzene: 4-ethyl-1,2-dimethoxy Benzene. * One Alkaloid: Caffeine. Overall, it is clear how all the samples are similar and consequently how the packaging protection does not cause a significant change on the volatiles detected, but only has an influence in the abundance level of several of them. This result was validated using the statistical analysis of ANOVA and T of Tukey in order to verify which samples were statistically different between each other. The ANOVA test was performed on all the compounds for each sample with and without capsule. ANOVA results showed a \(p\)-value of 0.0017 which indicates that there are differences between the various types of samples. To verify which extracted coffees were different from each other Tukey test showed that the only significant differences statistically significant are between Biologico (capsule)--Guatemala (no capsule) and Guatema (capsule)-Guatemala (no capsule) with a \(p\) value of 0.0032 and 0.0289, respectively. Regarding PCA analysis the results are shown in Figures 5-8. In all four cases the comparison was made between the volatilome of the sample with and without capsule. Figure 5: PCA score showing the comparison between volatile spectra compound of Biologico coffee “with capsule” and “without capsule” exhibiting an EV (explained variance) = 72.74%. Figure 6: PCA score showing the comparison between volatile spectra compound of Deciso coffee “with capsule” and “without capsule” exhibiting an EV (explained variance) = 76.10%. Figure 7: PCA score showing the comparison between volatile spectra compound of Dolce coffee “with capsule” and “without capsule” exhibiting an EV (explained variance) = 74.03%. We can conclude overall that PCA previously showed the EV was never under the 72%. This represents an optimum result since at least the 72% of the total variability of the samples was enclosed between the hyperplane (enclosed between the first two principal components), PC1 always being the component with a larger load, reaching 53% in the case of the Deciso samples. As a matter of fact, the PCA shown in Figures 5-8 confirm what was previously discussed. It is clear how the three replicates for all the four samples extracted with capsule create a compact cluster (S4, S5, S6), separated on the hyperplane compared with that formed by the ones without capsule (S1, S2, S3). In addition, PCA analysis confirms another aspect of this study.