## 3 Results and Discussion
### Mechanical Properties  
The films proposed for food packaging applications must meet certain mechanical properties. Tensile strength (TS) is considered to be the highest stress the film can endure prior to breaking and percentage elongation to break (EB) provides information about the deformation of films before breakage while Young's modulus (YM) provides some information on the deformation before fracturing [52; 53]. The mechanical characteristics of the films are shown in Table 4. The incorporation of TC into the film formulation significantly altered the mechanical parameters with statistical significance (\(p<0.05\)). The pectin film without oil was mechanically more resistant to fracture with a TS value of 10.37 MPa, which was significantly decreased by adding TC nanoemulsion in the range of 67 to 12% from pectin film as a control to P/NE:1 and P/NE:4 ones, respectively.  
Figure 1: Visual aspect of film samples with different concentrations of _trans_-cinnamaldehyde: control (0%), P/NE:1 (5.00%), P/NE:2 (3.33%), P/NE:3 (2.50%) and, P/NE:4 (2.00%) (first line); microscopic images of the surface 1000\(\times\) (SEM, middle line) and cross-sectional 800\(\times\) (SEM, third line) of the pectin films with different contents of trans-cinnamaldehyde.  
The percentage of EB decreased for the highest TC concentration (5%) and increased for lower concentrations (2.0%, 2.5%, and 3.3%) compared to pectin films without TC. Another study also reported an increase in EB% by adding _Cinnamomum verum_ into pectin films [54]. The presence of TC in the pectin film matrix resulted in a decrease not only in TS values, but also the elastic modulus. The incorporation of TC into the pectin film resulted in a decrease in Young's modulus values ranging from about 68 to 19% for TC concentrations ranging from 5.00 to 2.00%. The load parameters (TS and EB) were usually dependent on the microstructure film network and the intermolecular interactions [47; 55]. The integration of TC into the film matrix results in softer films that are more prone to breaking and exhibit lower stretchability. This behavior could be due to the presence of structural discontinuities in the film network triggered by the lipid dispersed phase, leading to weak mechanical responses. Our results are in agreement with some previous studies showing a reduction in the tensile strength of polysaccharide films when a lipid is incorporated into the matrix of a biopolymer as reported By [56]. These authors incorporated different concentrations of bergamot, lemon, and tea tree essential oils into hydroxypropyl methylcellulose and chitosan, leading to significant reduction in the TS, EB% and elastic modulus of the films. In another study, chitosan-based films containing 0.5%, 1%, 2%, and 3% (\(w/w\)) bergamot essential oil showed lower resistance to break, lower deformable and lower tensile strength [55]. However, some studies reported an improvement in mechanical parameters in the presence of essential oils. The addition of clove oil into pectin films significantly increased the TS, YM, and EB% of the pectin films. This improvement was explained by the effect of chemical similarity between the clove oil particles and the pectin matrix, which favors a stronger interaction between the biopolymer matrix and dispersed particles [57]. Depending on the particular interactions between different types of polysaccharides and essential oils, the mechanical behavior varied according to different studies. It could be attributed to the effect of different materials and formulations and the use of various plasticizers and surfactants, temperature and relative humidity, etc. [55].