## 3 Results and Discussions
### FT-IR Analysis  
The Fourier Transformed Infrared Spectra of yeast films were divided for better visibility into 400-1600 cm\({}^{-1}\) and 1600-7000 cm\({}^{-1}\) (Figure 4a,b) and indicated the presence of functional groups characteristic for yeast, as previously reported by [39]: peaks at approx. 1034 cm\({}^{-1}\) specific to C-O groups from polysaccharides, at approx. 1540 cm\({}^{-1}\) indicating amide II (proteins, C-N stretching, and N-H bending), as well as at approx. 1623 cm\({}^{-1}\) representing amide I (proteins, C=O stretching). \begin{table}
\begin{tabular}{c c c c c c} \hline
**Yeast Film Samples** & **Thickness, mm** & **Dry Matter, \%** & **aw** & **\(\Delta\)E** & **Opacity, \%** \\ \hline Y1-CNC & 0.19\(\pm\) 0.02 a & 83.448 \(\pm\) 0.115 a & 0.305 \(\pm\) 0.006 b & 22.55 \(\pm\) 0.01 a & 59.64 \(\pm\) 0.04 a \\ Y2-CNC & 0.20 \(\pm\) 0.02 a & 83.505 \(\pm\) 0.384 a & 0.314 \(\pm\) 0.007 b & 19.87 \(\pm\) 0.04 c & 59.10 \(\pm\) 0.00 a \\ Y3-CNC & 0.19 \(\pm\) 0.02 a & 83.571 \(\pm\) 0.324 a & 0.443 \(\pm\) 0.003 b & 21.93 \(\pm\) 0.20 b & 60.67 \(\pm\) 0.02 a \\ Y1c & 0.19 \(\pm\) 0.02 a & 72.740 \(\pm\) 0.071 b & 0.561 \(\pm\) 0.090 a & & 48.01 \(\pm\) 0.05 b \\ Y2c & 0.20 \(\pm\) 0.02 a & 72.091 \(\pm\) 0.145 b & 0.562 \(\pm\) 0.080 a & & 51.34 \(\pm\) 0.04 b \\ Y3c & 0.19 \(\pm\) 0.02 a & 72.374 \(\pm\)0.368 b & 0.589 \(\pm\) 0.070 a & & 52.52 \(\pm\) 0.04 b \\ \hline \end{tabular}
\end{table} 
Table 1: Physical properties of yeast films. Figure 3: Yeast films functionalized with 2.0% CLEO and 2.0% CNC from left to right: Y1-CNC, Y2-CNC, Y3-CNC. The absorbance intensity for amide II in Y-CNC films decreased 1.12 times compared to amide I, which could be explained by the sensitivity of N-H groups from amide II to hydrogen bonding [39]. The influence of increasing concentrations of glycerol as plasticizer is related to a decreased intensity for amide I and II in yeast film samples. The influence of Tween as a peak at approx. 1733 cm\({}^{-1}\) appears visible only in the spectra of Y3-CNC and Y3c, where it has the highest concentration of all samples (1.50%), while for the other two concentrations, samples with 1.25% or 1.00% Tween is less visible, neither in functionalized Y-CNC, nor in control Y films. FTIR spectra of CNC (Figure 4a) indicates, in the group frequency region, the most intense absorption peak at 3277 cm\({}^{-1}\) characteristic for O-H stretching of strong hydrogen bonds in cellulose I, at 2916 cm\({}^{-1}\) for the C-H stretching, previously correlated to cellulose I and II [40]; analysis of the fingerprint region (Figure 4b) shows peaks at 1239 cm\({}^{-1}\) corresponding to C-H and CH\({}_{2}\) bending and at 1090 cm\({}^{-1}\) due to C-O stretching [41]. The analysis of CNC-grafted yeast films spectra (Figure 4b) indicates peaks at 3277 cm\({}^{-1}\) distinctive for O-H stretching in cellulose I (intensities of 69.392% in Y1-CNC, 69.093% in Y2-CNC, 74.244% in Y3-CNC), at 2922 cm\({}^{-1}\) corresponding to C-H stretching from cellulose I and II (intensities of 74.304% in Y1-CNC, 75.049% in Y2-CNC, 73.721% in Y3-CNC) and at approx. 1240 cm\({}^{-1}\) related to C-H and CH\({}_{2}\) bending (intensities of 70.887% in Y1-CNC, 73.330% in Y2-CNC, 72.881% in Y3-CNC), suggesting the successful incorporation of CNC in all three yeast films. The spectra of CLEO mixture reveals peaks specific for both lavelander and cinnamon, as the 848 cm\({}^{-1}\) characteristic for monoterpenes or the one at 1733 cm\({}^{-1}\), indicating C-O presence, which can be related to cinnamaldehyde, a cinnamon marker [42]; peaks which can be identified in the current yeast films (Y-CNCs). Moreover, cynamaldehyde can act as a crosslinker in developing 3D polymeric networks, and its presence in Y-CNC spectra can only be justified by the presence of grafted CNC [8]. Figure 4: FTIR spectra of CNC, CLEO and grafted CNC on yeast films, from 400 to 1600 cm\({}^{-1}\) (**a**) and 1600-7000 cm\({}^{-1}\) wavenumber (**b**), molecules demonstration in FTIR spectra of Y1-CNC (**c**), PCA scores and clusters (**d**).