## 2 Results and Discussion
### PTR-ToF-MS Results and Comparison with HS-SPME GC-MS Findings
In detail, the figure proposes the behaviors corresponding to the peaks at _m_/ 73.065 (tentatively identified as 2-butanone), _m_/ 75.044 (tentatively identified as propionic acid), m/z 83.086 (tentatively identified as hexanol fragment), _m_/ 87.080 (tentatively identified as 2-pentanone/isoprenol), _m_/ 98.105, and _m_/ 101.096 (tentatively identified as 2-hexanone). The intensity corresponding to the mass peak _m_/ 73.065 reaches the highest values in the delactosed samples produced by Manufacturer C, while the standard productions belonging to the same manufacturer registered the lowest values (as all mascarpone batches of Producer M) (Figure 2a). Samples from Manufacturers A and B present intermediate intensities for this peak (Figure 2a). In accordance with these results, 2-butanone was found to be variable in different types of whey [30]. In only the M2 batch did we detected a relevant intensity for the mass peak _m_/ 75.044 (Figure 2b), tentatively identified as propionic acid, a compound that can be responsible for a dairy taste/odor with a pronounced fruity lift [31]. The mass peak _m/z_ 83.086 has been found with pronounced intensities in the samples produced by the Manufacturers A and B (Figure 2c). Hexanal was included among the high-content compounds identified in samples belonging to dairy products [32] and described as having a fatty, green, grassy, powerful, penetrating characteristic fruity odor and taste [31]. A similar trend can be underlined for the intensities of mass peak _m/z_ 101.096 (Figure 2f). Finally, a considerable variability can be highlighted for the intensities corresponding to the mass peaks m/z 87.080 and 98.105 (Figure 2d,e). Other than this kind of punctual analysis, PTR analysis offers also the opportunity to depict a global analysis of molecular fingerprinting associated with the headspace of the different samples. Considering that the present work deals with an integrated analytical approach, we propose a PTR data set selected in light of the comparison with GC data. In fact, we defined a new subset of the PTR-ToF-MS data including only the mass peaks that were found also using the HS-SPME GC-MS technique. As a result, we have a new matrix (Table 2) of twenty peaks corresponding to the masses of protonated molecular ions of compounds such as acetic acid (sour pungent, cider vinegar, slightly malty with a brown nuance; naturally occurring in various dairy products, it has a role in butter and cheese flavors), acetoin (acidic, sour, cheesy, dairy, creamy with a fruity nuance; normally occurs  
Figure 2: The boxplots indicated by letters (**a–f**) represent selected volatiles found in association with the different commercial macarxpone samples such as m/z 73.0649–C\({}_{4}\)H\({}_{9}\)O\({}^{*}\)—t.i. 2-Butanone, 75.0437—C\({}_{3}\)H\({}_{7}\)O\({}_{2}\)\({}^{*}\)—t.i. Methyl acetate, 83.0860—C\({}_{6}\)H\({}_{11}\)\({}^{*}\)—t.i. fragment of Hexanal/Hexenol, 87.0809—C\({}_{6}\)H\({}_{11}\)O\({}^{*}\)—t.i. 2-Pentanone/3-Buten-1-ol, 3-methyl-, 98.1048—isotope of C\({}_{7}\)H\({}_{13}\)\({}^{*}\)—t.i. Heptanal, 101.0968—C\({}_{6}\)H\({}_{13}\)O\({}^{+}\)—t.i. 2-Hexanone. Different letters indicate a significant difference between different samples (_p_ \(<\) 0.05, one-way ANOVA, Tukey HSD). in butter, milk, and cheeses), acetone (characteristic aromatic odor, pungent, somewhat sweet taste; naturally occurring in fermented dairy products), ethanol (slight, characteristic odor and a burning taste; naturally occurring in blue cheese, cheddar cheese, Swiss cheese), furfural (characteristic penetrating odor typical of cyclic aldehydes; naturally occurring in cheeses), hexanoic acid (sickening, sweaty, rancid, sour, sharp, pungent, cheesy, fatty, unpleasant odor reminiscent of copra oil; naturally occurring in cheeses, butter, milk), and octanoic acid (mildly unpleasant odor and a burning, rancid taste, also reported as having a faint, fruity-acid odor and slightly sour taste; natural component of butter fat, occurring in cheeses) [31; 33].