## 2 Materials and Methods
### Analytical Determinations
#### 2.5.3 Packaging Material Performance  
Packaging materials were tested for gas permeability, thermal properties, and global migration before and immediately after the application of plasma treatment. Permeability measurement was performed using a manometric method, by the evaluation of gas transmission rate (GTR, expressed in cm\({}^{3}\)/m\({}^{2}\) day bar) for O\({}_{2}\) and CO\({}_{2}\) on a permeence testing device, type GDP-C (Brugger Feimmechanik GmbH, Munchen, Germany), in accordance with ASTM 1434 (standard test method for determining gas permeability characteristics of plastic film and sheeting, 2009), DIN 53536 (gas permeability determination), ISO 15105-1 (plastic film and sheeting determination of gas transmission rate--Part I: Differential pressure methods, 2007), and the Gas Permeability Testing Manual, 2008 (Registergericht Munchen HRB 77020, Brugger Feimmechanik GmbH). A mean value from triplicate experiments was considered [15; 16; 17]. Film and tray thickness (\(\delta\)) was measured using a Sample Thickness Tester DM-G with a digital dial indicator (MarCator 1086 model, Mahr GmbH, Esslingen, Germany) and associated DM-G software. The reading was made twice per second, with a resolution of 0.001 mm. The minimum, maximum, and average of each reading was recorded in triplicate, in 10 different positions for each film at room temperature, and reported as mean thickness value, expressed in microns. Thermal properties were evaluated by differential scanning calorimetry (DSC) using a DSC model Q20 (TA Instrument, New Castle, DE, USA) equipped with a cooling unit (TA Refrigerated Cooling System 90). The calibration of the instrument was performed \begin{table}
\begin{tabular}{c c c} \hline
**Selected** & **O\({}_{\mathbf{S}}\)** & **NO\({}_{\mathbf{2}}\)** \\
**Wavelength** & **Cross-Section** & **Cross-Section** \\ \hline
253 \(\pm\) 1.2 nm & (1.12 \(\pm\) 0.02) \(\times\)\(10^{-17}\) & (1.1 \(\pm\) 0.3) \(\times\)\(10^{-20}\) \\
400 \(\pm\) 1.2 nm & (1.12 \(\pm\) 0.08) \(\times\)\(10^{-23}\) & (6.4 \(\pm\) 0.2) \(\times\)\(10^{-19}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Absorption cross-sections in cm\({}^{2}\) of the species of interest at each selected wavelength. with distilled water (T\({}_{\rm m}\) 0.0 \({}^{\circ}\)C), indium (T\({}_{\rm m}\) 156.60 \({}^{\circ}\)C), and zinc (T\({}_{\rm m}\) 419.47 \({}^{\circ}\)C) under a dry nitrogen flow of 50 mL min\({}^{-1}\). Samples of about 10 mg were weighed in hermetically closed 50 \(\mu\)L aluminum DSC capsules. The samples were first equilibrated at a temperature of \(-\)30 \({}^{\circ}\)C for 5 min, then heated, with a first scanning rate of 10 \({}^{\circ}\)C/min, from \(-\)30 to 180 \({}^{\circ}\)C (for PP) and 280 \({}^{\circ}\)C (for PET) and then, after an isotherm of 3 min at 180 \({}^{\circ}\)C or 280 \({}^{\circ}\)C, samples were cooled to \(-\)30 \({}^{\circ}\)C at a rate of 80 \({}^{\circ}\)C/min. After a second isothermal step of 3 min at \(-\)30 \({}^{\circ}\)C, a second heating was performed with the same parameters as the first one (second scan). Peaks were integrated with TA Universal Analysis software (TA Instrument, New Castle, DE, USA) to determine the melting temperature (T\({}_{\rm m}\)) as the peak value of the endothermic phenomena in the DSC curve, and the melting enthalpy (\(\Delta\)H\({}_{\rm m}\)) from the area of the DSC endothermic peak. T\({}_{\rm m}\) and \(\Delta\)H\({}_{\rm m}\) values were collected from the first scan.