## 3 Results and Discussion
### The Behavior of VOCs in the Food Samples After Irradiation  
Beef, chicken, turkey, fish, and potato samples of 2 g each were placed in vials after irradiation with 2 mL of deionized water added, then sealed and subjected to GC-MS analysis. Figure 2 shows the heat map of the VOC concentrations normalized to the maximum value of each volatile compound identified in the irradiated and non-irradiated food samples. Various VOCs are plotted on the ordinate axis of the heat map, and the data on the abscissa axis are grouped by irradiation dose and product type. Quantitative VOC data in non-irradiated and irradiated beef, chicken, turkey, salmon, and potato samples can be found in Tables A1-A5 in Appendix A. \begin{table}
\begin{tabular}{c c} \hline
**GC-MS Parameters** & **Value** \\ \hline Column & VF-624 MS (60 m \(\times\) 0.32 mm, film thickness 1.8 \(\upmu\)m) \\ Split mode & 1:1 \\ Evaporation chamber temperature & 250 \({}^{\circ}\)C \\ Column temperature & 40 \({}^{\circ}\)C (5 min) \(\rightarrow\) (6 \({}^{\circ}\)C/min) 220 \({}^{\circ}\)C (5 min) \\ Carrier gas & Helium \\ Carrier gas flow rate & 1.5 cm\({}^{3}\)/min \\ Interface temperature 220 \({}^{\circ}\)C & 220 \({}^{\circ}\)C \\ Ion source temperature & 230 \({}^{\circ}\)C \\ Ionization mode & Electron ionization \\ Electron energy & 70 eV \\ Measurement mode & Scanning \\ Scanning range & \(m/z\) 33–350 \\ Scanning speed & 3.3 scan/s \\ \hline \end{tabular}
\end{table} 
Table 1: GC-MS analysis conditions. As can be seen from Tables A1-A5, the list of VOCs for different products differs significantly, with beef and salmon samples having higher amounts of detected volatile compounds compared to turkey, chicken, and potatoes. A higher amount of VOCs in salmon and beef samples can be attributed to a higher fat and protein content since irradiation triggers the oxidation of fatty acids and amino acids, which leads to the formation of a wide range of VOCs [41]. Irradiation of meat products in order to destroy biological contaminants affects the course of chemical reactions in food products and, accordingly, organoleptic properties. Irradiation generates highly reactive compounds that catalyze oxidative transformations of proteins and lipids, and the mechanisms of such transformations are usually very complex and not fully understood [30]. Figure 3 shows chromatograms of beef samples irradiated at different doses. There is a significant change in the content of some components, and the list of identified compounds expands with an increase in the radiation dose. As a result of GC-MS analysis, 16 compounds of various VOC classes were identified in irradiated beef samples, among which the most intense peaks belong to acetaldehyde, acetone, 2,3-butanedione, butanone-2, hexanal, and 2-methylpropanal. In turn, 14 compounds were found in the non-irradiated beef sample, and the butanal, 3-methyl, butanal, 2-methyl, hexanol-1, octanal, and 1-hexanol,2-ethyl found in the irradiated samples were not detected. The predominant classes of VOCs in beef samples are aldehydes, alcohols, and ketones, but thiols and sulfides have also been found. A total of 16 identified VOCs, as a result of the analysis of beef samples, were distributed into five classes. Thus, the list of VOCs in irradiated beef samples is larger than in the non-irradiated food samples, further referred to as control samples and shown as 0 kGy in graphs and tables, even at the lowest radiation dose of 0.25 kGy. Figure 2: Heat map of volatile organic compound concentrations in beef, chicken, turkey, salmon and potato irradiated with different doses, expressed in relative units. Dark blue cells show that the compound was not detectable. Figure 4 shows the chromatograms of beef, chicken, turkey, and salmon samples exposed to 1 kGy. Despite the fact that samples of all products were analyzed under the same conditions (under the same sample preparation conditions and GC-MS parameters) and were subjected to the same irradiation doses, they have significantly different VOC profiles.