## 3 Results and Discussion
### Smart Nose
\begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Chemical Class**} & \multirow{2}{*}{**Odour Perception**} & \multirow{2}{*}{**LRI \({}^{\text{a}}\)**} & \multirow{2}{*}{**Ident b**} & & \multicolumn{3}{c}{**278**} & \multicolumn{3}{c}{**369**} \\ \cline{6-10}  & & & & & \(b\)\({}^{\text{c}}\) & \(a\)1 d & \(a\)2 e & \(b\) & \(a\)1 & \(a\)2 \\ \hline Methylbutyric acid & Acid &
\begin{tabular}{c} Cheese, \\ Butyric \\ \end{tabular} & 367 & PI & X & & & & & X \\ \hline _Total acid_ & & & & 1 & \(0\) & \(0\) & \(0\) & \(0\) & 1 \\ \hline Nonanal & Aldehyde & Green & 1103 & PI & & & & X & & \\
2-Nonenal & Aldehyde & Green & 1143 & PI & X & & & & \\
2,6-Nonadienal & Aldehyde & Hay & 1149 & PI & X & & & & \\ \hline _Total aldehyde_ & & & & & 2 & \(0\) & \(0\) & 1 & \(0\) & \(0\) \\ \hline Safrole & Aromatic & \begin{tabular}{c} Unpleasant \\ Hyd \\ \end{tabular} & 1280 & PI & X & X & & & & & \\ \hline _Total aromatic hydrocarbon_ & & & & \(0\) & 1 & \(0\) & \(0\) & \(0\) \\ \hline Ethyl butyrate & \begin{tabular}{c} Ester \\ Ester \\ \end{tabular} & \begin{tabular}{c} Apple \\ Orange \\ Wine, Fruity \\ \end{tabular} & \begin{tabular}{c} 798 \\ 842 \\ Win, Fruity \\ \end{tabular} & \
\begin{tabular}{c} PI \\ 1185 \\ \end{tabular} &
\begin{tabular}{c} X \\ PI \\ \end{tabular} & X & & & X & & X & \\ \hline _Total ester_ & & & & 2 & 2 & 1 & 3 & 3 & 2 \\ \hline Diacetyl & Ketone & Butter & 639 & PI & X & X & X & X & X \\ Heptanone & Ketone & Sweet & 895 & PI & X & X & & & \\
1-Octen-3-one & Ketone & Mushroom & 973 & PI & X & X & & X & \\
2-Nonanone & Ketone & Hot milk & 1082 & PI & X & X & & X & \\
3,5-Octadien-2-one & Ketone & Mushroom & 1095 & PI & & X & & X & \\ \hline _Total ketone_ & & & & & 3 & 5 & 5 & 1 & \(4\) & \(4\) \\ \hline Acetylpyrazine & Pyrazine &
\begin{tabular}{c} Roast, \\ Rancid \\ \end{tabular} & 1027 & PI & & & & & & & X \\ \hline _Total pyrazine_ & & & & & \(0\) & \(0\) & \(0\) & 1 & 1 \\ \hline Thiophene & Sulfur & Garlic & 665 & PI & X & X & & & \\ Methional & Sulfur & Potato & 905 & PI & X & & & X & X \\ Butyl isothiamate & Sulfur & Garlic & 956 & PI & X & X & X & X & X \\ \hline _Total sulfur_ & & & & & 2 & 2 & 2 & 1 & 2 & 2 \\ \hline
2,3-Dehydro-1,8-cineole & Terpene & Orange & 990 & PI & X & X & X & X & X & X \\ (Z)-Linalool oxide & Terpene & Wine, Fruity & 1073 & PI & X & X & X & X & X & X \\ (+)-cis-Rose oxide & Terpene & Wine, Fruity & 1112 & PI & X & X & X & X & X & X \\ \hline _Total terpene_ & & & & & 3 & 3 & 3 & 3 & 3 & 3 \\ \hline
**Total compounds** & & & & & **13** & **13** & **12** & **9** & **13** & **13** \\ \hline \hline \end{tabular}  
* Linear Retention Index with a hHP-5 column. b Identification: PI, comparison with LRI flavour database. c The 0.0-kGy irradiation treatment. d The 5.0-kGy irradiation treatment at 500 g. e The 5.0-kGy irradiation treatment at 250 g.  
\end{table} 
Table 4: Odour Active Compounds of artisanal pecorino-style hard cheese samples at the 0.0-kGy and 5.0-kGy radiation dosages. safrole is carcinogenic. [PERSON] et al. [46] also reported unfavourable alterations in the cheese odour when samples are irradiated at doses of 1.51 kGy and 2 kGy. Free radicals are produced during the irradiation treatment, which might trigger lipid and/or protein oxidation, leading to the production of secondary oxidation products such as alkanes, alkenes, aldehydes, alcohols, ketones and acids [47]. Secondary oxidation products are also broken down into volatile compounds and/or undergo polymerisation, cyclisation and isomerisation that might give of a fishy, metallic, rancid and oxidised odour perception [48]. By comparing the presence/absence of specific compounds in the two samples, 369 had methylbutyrate acid only in subgroup \(a\)2, different from sample 278 that, as said before, were present in the \(b\) group. Moreover, 1-octen-3-one and 2-nonanone were present in the \(a\)1 and \(a\)2 subgroups, different from sample 278, for which they were present in all groups.