## 3 Results and Discussions
### Yeast Films Characterization
#### 3.3.4 The Steric and Electrostatic Interactions  
The results of antimicrobial assay of CLEO per se indicated that all three test microorganisms were inhibited by 1% (\(w/w\)) CLEO, the MIC value. CLEO had a potential fungicidal effect if used at a concentration of 1% (\(w/w\)), corresponding to the MFC for _Geotrichum candidum_ and _Rhodotorula glutinis_, and a bactericidal effect against _Bacillus cereus_ if 2% (\(w/w\)) CLEO (MBC) was used. Considering these results, the YF films were functionalized with CLEO 2% (\(w/w\)).  
Evaluation of CLEO antimicrobial efficacy functionalizing YF (Table 4), by disk diffusion assay, was differentiated considering a minimum inhibition diameter of 12 mm as the presence of inhibition activity, a mildly inhibitory effect with inhibition zones ranging between 12 and 20 mm, and strongly inhibitory activity with inhibition diameters higher than 20 mm [41]. Control samples YF1-3c did not exhibit any inhibitory activity against the three test microorganisms.  
According to this classification, the functionalized YF with 2% (\(w/w\)) CLEO exerted a mild inhibitory effect against _Bacillus cereus_ and a strong antifungal effect against _Geotrichum candidum_ and _Rhodotorula glutinis_. The antimicrobial activity of CLEO is due to major constituents of cinnamon EO and lavender EO. For example, phenolic terpenids like eugenol identified in cinnamon EOs exert antimicrobial activity with a broad spectrum. Likewise, \(\beta\)-caryophyllene, a sesquiterpene specific for cinnamon, clove, and rosemary EOs, is also associated with major constituents with antimicrobial effects [41]. Nonetheless, the presence of \(\alpha\)-pinene and eucalypt from lavender contributes to the total antimicrobial activity. The antibacterial mechanism of cinnamon--lavender EOs--mostly relies on bacterial membrane disruption and changes in the membrane's lipid profile, ATPase activity, and membrane porins inhibition, together with an anti-quorum sensing effect [42]. However, the mechanism of lavender EO is not fully deciphered, which seems to be linked with the susceptibility to changes of the bacterial wall structure [43]. Similarly, it was suggested that eugenol changes the cell wall permeability of G(\(-\)) bacterial membrane, producing intracellular leakage and then cell lysis [44].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Test Microorganism** & **YF Sample** & **YF1** & **YF2** & **YF3** & \(p\)**-Value** \\ \hline _Bacillus cereus_ & 14.95 \(\pm\) 0.25 \({}^{\mathrm{\,\AA}}\) & 15.08 \(\pm\) 0.30 \({}^{\mathrm{\,\AA}}\) & 15.29 \(\pm\) 1.24 \({}^{\mathrm{\,\AA}}\) & 0.858 \\ _Geotrichum candidum_ & 21.00 \(\pm\) 0.30 \({}^{\mathrm{\,\AA}}\) & 23.28 \(\pm\) 0.46 \({}^{\mathrm{\,\AA}}\) & 23.60 \(\pm\) 0.68 \({}^{\mathrm{\,\AA}}\) & 0.001 \\ _Rhodotorula glutinis_ & 27.00 \(\pm\) 0.58 \({}^{\mathrm{\,\AA}}\) & 27.99 \(\pm\) 1.97 \({}^{\mathrm{\,\AA}}\) & 26.44 \(\pm\) 0.38 \({}^{\mathrm{\,\AA}}\) & 0.347 \\ \(p\)-value & 0.000 & 0.000 & 0.000 & 0.000 \\ \hline \hline \end{tabular} Different lowercase letters indicate significant differences (\(p<0.05\)) on the columns, and uppercase letters indicate differences on the rows, determined by unifactorial ANOVA and Tukey’s root test.  
\end{table}
Table 4: Inhibition zones of functionalized YFs with CLEO. Results are average \(\pm\) SD of two independent replicates, expressed in mm.  
Figure 4: Transparency of yeast films: (a) YF1; (b) YF2; (c) YF3.  
The results presented in Table 3 are correlated with the ones presented in the heat map for retention rates of VOCs by the YFs in comparison with the CLEO fingerprint, suggesting that the significantly (\(p<0.05\)) higher antifungal activity of YF2 and YF3 in comparison with that of YF1 could be due to molecules like eugenol, cinnamaldehyde, and cinnamyl alcohol acetate present in higher concentrations in YF2 and YF3.