## 3 Results
### Release Test
Dependence on the concentration of the loaded SCG extract was not regular as for casted films (Figure 6a), especially for samples loaded with the 20% \(w/w\) concentration of extract, which exhibited fast delivery of caffeine after 6 h, reaching the performance of samples with 45% \(w/w\) of extract. The spin coating process, involving centrifugal forces during the fabrication, could have provided an extract distribution near the external surface, which could explain the faster migration compared to solvent casting samples. The higher rate of extract release was also confirmed by the greater inhibition effect of aliquots of food simulant tested by ABTS assay (Figure 6b). Indeed, only at the lowest concentration of extract loaded, inhibition observed was comparable with that of casted samples, while for loadings higher than 15% \(w/w\), the observed values were immediately above 40%, increasing up to 4 h of release. Such fast migration made the extract available for degradation reactions, which explains the lower inhibition effect encountered at times longer than 4 h. Moreover, plasticizing effects are associated to the introduction of phenolic compounds and lipids into biopolymer-based packaging [40; 41]. The different distribution of loaded compounds can have affected the overall structure of the films and the release of the active agents. The different behavior encountered for casted and spin coated films was also observed by [PERSON] et al., 2020, who compared the two production processes in the fabrication of amaranth protein isolate-based thin films, finding a strong dependance of the physical properties of the product on the production method [42]. Consequently, the relationship between the released caffeine (and extract) and inhibition power was no longer linear, as for solvent casting, indicating the occurrence of activity losses of the antioxidants. Figure 6: Results of the release tests on films obtained by spin coating in ethanol 10% (\(v/v\)), in terms of: (**a**) caffeine released per kg of film, (**b**) radical ABTS\({}^{\bullet\star}\) inhibition. Different symbols indicate statistically significant differences among values over time (\(p<0.05\)) of dataset with the same extract loading. Electrospun mats are characterized by a fibrous structure, which facilitates the release of active components due to the larger surface available for mass transfer. Consequently, the released mass of caffeine plateaued very fast (Figure 7a) for all the extract loadings tested. Therefore, the extract was almost completely delivered in the early hours, implying its availability to degradation reactions, as can be observed through Figure 7b, where the decrease over time of the inhibition ability is shown for all the tested samples. This evidence shows that the technique adopted for loaded film production can affect the properties of the active system, allowing the most sustained release in solvent casted packaging and the fastest in electrospun mats. The different production methods can be thus applied to tune the rate of migration for the active agent, according to the specific application, planned shelf-life of the food, and the velocity of food spoilage, and the degradation reaction. Active packaging by solvent casting ensure protection against food oxidation less intense initially but increasing and sustained over time, while electrospun mats allows an immediate and intense action to counteract oxidation for those foods that rapidly tend to modify their organoleptic properties. Furthermore, an intermediate action can be achieved by spin coated active films. This finding supported the importance of further investigations into the effect of the production technique on the antioxidant activity of active packaging, as also highlighted by [PERSON] et al., 2018 [PERSON] et al. (2018).