## 3 Results and Discussion
### Aroma Retention Capacity  
Prior research involving roasted peanut flavor have reported that many of the substances perceived by evaluators are aldehydes and pyrazines [41]. In this sense, pyrazines are responsible for the roasted and nutty flavor in peanuts and nonanal produces a milky and toasty flavor [41; 42]. Accordingly, 2,3-dimethylpyrazine (2,3-DMP), 2,6-dimethylpyrazine (2,6-DMP) and nonanal have been employed in the present work as indicators of the aroma incorporation in the developed films.  
PA initial analysis indicated that 2,3-DMP, 2,6-DMP and nonanal were present at 2.44 wt %, 1.60 wt % and 0.34 wt % levels, respectively. Based on this and considering that an initial amount of 5 wt % of PA was added into the LDPE-based films, 0.12 wt % of 2,3-DMP, 0.08 wt % of 2,6-DMP and 0.02 wt % of nonanal are the maximum contents of these compounds present in the films if an incorporation of 100% is assumed.  
The quantification of these compounds in films proved that commercial PA was successfully incorporated into PE and PE/PB based formulations. The content of 2.3-DMP found in PE/PA, PE/PA/PB5 and PE/PA/PB13 was 66 \(\pm\) 14, 63 \(\pm\) 9 and 93 \(\pm\) 13 ppm, respectively reporting a higher significant amount of this compound in the formulation PE/PA/PB13. In relation to the 2,6-DMP, the content present in the PE/PA, PE/PA/PB5 and PE/PA/PB13 samples was 139.6 \(\pm\) 23.3, 117 \(\pm\) 18 and 165 \(\pm\) 24 ppm, respectively. Data showed significant differences between the formulations with different wt % of PB, resulting in a higher presence of this compound in the PE/PA/PB13 formulation (Figure 5). It is important to consider that these concentrations were higher than the concentrations of pyrazines generated during the roasting process of peanuts [43], indicating that the levels of both pyrazines incorporated into the LDPE-based films were suitable to improve the customer's sensorial experience. On the other hand, in relation to the nonanal content present in the developed films, values of 72 \(\pm\) 19, 131 \(\pm\) 30 and 136 \(\pm\) 31 ppm were obtained in samples of PE/PA, PE/PA/PB5 and PE/PA/PB13, respectively. Significant differences were observed among PE/PA films and the ones containing PB at 5 wt % and 13 wt % indicating a positive effect of the addition of PB in the final amount of nonanal present in the films despite the high volatility of this compound.  
Based on the sum of the individual retentions of the main aroma compounds (i.e., 2,3-DMP, 2,6-DMP and nonanal) no significant differences between the retention capacity of PA into PE/PA and PE/PA/PB5 films was found (12.7% \(\pm\) 2.6% and 14.2% \(\pm\) 2.6% respectively). However, the retention capacity of the aroma in PE/PA/PB13 films was significantly higher (18.0% \(\pm\) 3.1%). Consequently, the incorporation of PB in high levels into a LDPE matrix improved the PA retention. This behavior could be attributed to the ability of PB in enhancing crosslinking of LDPE as the concentration of PB increases as reported by other authors [37]. In relation to the retention of aroma compounds in crosslinked polymer matrices, higher retention values have been reported because of the higher interactions between aroma compounds and polymer chains that occur in comparison with non-crosslinked polymers [43].