## 3 Results and Discussion
### Characterization of Films Processed at Pilot Scale
#### 3.2.4 Oxygen Absorption and Kinetics  
The oxygen scavenging capacity of the ML/LDPE_CAR films developed by cast film extrusion at pilot scale was also evaluated, since oxygen content accelerates food spoilage in fatty food. In a preliminary test, the O\({}_{2}\) absorbed per film amount was monitored for a week, performing a measurement each day. Figure 3 shows that \(\beta\)-carotene films absorbed the oxygen present in the headspace from the first day to the third day of exposure to air. From then on, their oxygen absorption capacity remained constant. For this reason, the oxygen measurements from the headspace of the 20 mL-vials were carried out after three days of the air exposure.  
Figure 3: Oxygen absorption kinetics of ML/LDPE_CAR film.  
\begin{table}
\begin{tabular}{c c c c} \hline  & **ML** & **ML/LDPE\_CAR** & **Layer** \\ \hline T\({}_{\rm ini}\) (\({}^{\circ}\)C) \({}^{\star}\) & 401 \(\pm\) 1 \({}^{\rm a}\) & 397 \(\pm\) 2 \({}^{\rm b}\) & \\ T\({}_{\rm max}\) (\({}^{\circ}\)C) & 469 \(\pm\) 2 \({}^{\rm b}\) & 473 \(\pm\) 1 \({}^{\rm a}\) & \\ T\({}_{\rm c}\) (\({}^{\circ}\)C) 1 & 93 \(\pm\) 0 \({}^{\rm b}\) & 95 \(\pm\) 0 \({}^{\rm a}\) & \\ T\({}_{\rm c}\) (\({}^{\circ}\)C) 2 & 102 \(\pm\) 0 \({}^{\rm a}\) & 101 \(\pm\) 0 \({}^{\rm b}\) & \\ A\({}_{\rm H}\) (\(\beta\) \({}^{-1}\)) & 58.6 \(\pm\) 0.8 \({}^{\rm b}\) & 65.9 \(\pm\) 0.8 \({}^{\rm a}\) & LDPE \\ T\({}_{\rm m}\) (\({}^{\circ}\)C) 1 & 102 \(\pm\) 0 \({}^{\rm b}\) & 105 \(\pm\) 0 \({}^{\rm a}\) & \\ T\({}_{\rm m}\) (\({}^{\circ}\)C) 2 & 111 \(\pm\) 0 \({}^{\rm a}\) & 111 \(\pm\) 0 \({}^{\rm a}\) & \\ A\({}_{\rm Hm}\) (\(\beta\) \({}^{-1}\)) & 55.6 \(\pm\) 1.9 \({}^{\rm b}\) & 68.6 \(\pm\) 1.7 \({}^{\rm a}\) & \\ X\({}_{\rm c}\) (\%) & 19 \(\pm\) 1 \({}^{\rm a}\) & 20 \(\pm\) 1 \({}^{\rm a}\) & \\ T\({}_{\rm m}\) (\({}^{\circ}\)C) 1 & 182 \(\pm\) 0 \({}^{\rm a}\) & 176 \(\pm\) 6 \({}^{\rm a}\) & \\ A\({}_{\rm Hm}\) (J g\({}^{-1}\)) & 6.27 \(\pm\) 0.05 \({}^{\rm a}\) & 3.4 \(\pm\) 0.2 \({}^{\rm b}\) & EVOH \\ T\({}_{\rm m}\) (\({}^{\circ}\)C) 1 & 254 \(\pm\) 0 \({}^{\rm a}\) & 253 \(\pm\) 0 \({}^{\rm b}\) & PET \\ A\({}_{\rm Hm}\) (J g\({}^{-1}\)) & 9.5 \(\pm\) 0.4 \({}^{\rm a}\) & 6.1 \(\pm\) 1.1 \({}^{\rm b}\) & \\ Old (trim) & 4.5 \(\pm\) 0.3 \({}^{\rm b}\) & 14.1 \(\pm\) 0.3 \({}^{\rm a}\) & \\ \hline \end{tabular} \({}^{\rm a}\) Results expressed as the mean \(\pm\) standard deviation of three replicates (\(\alpha\) = 0.05). \({}^{\rm t}\) Different superscripts in the same raw indicate statistically significant different values (\(p<0.05\)).  
\end{table}
Table 3: Thermal properties and oxygen induction time (Olt) of multilayers films ML and ML/LDPE_CAR \({}^{\#,\dagger}\).  
The amount of oxygen absorbed (mL) by ML/LDPE_CAR films after three days at 30 \({}^{\circ}\)C was evaluated. As it is shown in Figure 2, oxygen absorption capacity was \(1.7\pm 0.3\) mL O\({}_{2}\) per g of ML/LDPE_CAR. It is important to notice oxygen absorption capacity between LDPE_CAR and ML/LDPE_CAR film did not show significant differences, in spite of thicknesses being different. Reactions between oxygen and \(\beta\)-carotene inside the films depend on the concentration of \(\beta\)-carotene and the thickness of the film. [PERSON] et al. verified the \(\beta\)-carotene decomposition time in light was significantly longer in 1 mm thickness films than in 100 um thickness films (independently of the initial concentration) [34]. To the best of our knowledge, the oxygen absorption capacity of natural compounds such as \(\beta\)-carotene incorporated in a polymeric matrix had not been tested before. ML/LDPE_CAR films were employed to pack 200 g of fried peanuts. When food is packaged under a modified atmosphere or in vacuum, residual oxygen levels from 0.3 to 3.0% remain inside the package [35]. Then, as the developed bags absorb 3.7% of oxygen, \(\beta\)-carotene concentration at 10 wt.%. was appropriated for this application. However, peanuts were packaged with air to accelerate the oxidation process.