## 3 Results and Discussion
### Stability toward Centrifugation  
The emulsion phase of the samples with the highest viscosities for each CMF dose (0.50, 0.75, and 1.00 wt%) and OCEP between 62% and 68% was observed by optical microscope before and after centrifugation at 500 rpm for 2 min. In addition, emulsions with higher OCEP (75%-80%) and lower OCEP (52%-59%) with respect to the ones that had the maximum \(\mu_{\mathrm{a}}\) were also studied (Figure 8). According to these results, a stabilized emulsion could be defined as the one which maintained the number, the size, and the shape of oil droplets after centrifugation without the coalescence of droplets and a mixture of oil and water phases. As can be observed in Figure 8, for emulsions with a CMF dose of 0.50 wt% before centrifugation, the emulsion with the highest \(\mu_{\mathrm{a}}\) (40/60 O/W ratio) and around 65% OCEP had droplets with a small size and CMF (in black) distributed around them. However, 30/70 and 50/50 O/W emulsion droplets were more separated and had bigger size and irregular shape. In this case, CMF stacks could be observed in aqueous phase. After centrifugation, the emulsion with the highest \(\mu_{\mathrm{a}}\), around 6.3 Pa\(\cdot\)s, maintained the size and shape of droplets with a homogeneous CMF distribution and without phase separation in the test tube, showing this emulsion to be quite stable toward centrifugation. However, although 52.9% OCEP emulsion contained a similar size of droplets, it had a more irregular shape of droplets, making the continuous fluid phase clearer. A small water phase on the base of the test tube and a small amount of oil phase on the top could be seen. Low viscosity emulsion with 79.5% OCEP emulsion had a big size and an irregular shape of droplets after centrifugation. Drop numbers decreased because they passed to the continuous liquid phase, and the test tube showed phase separation. These facts indicate that the emulsion with the highest viscosity (6.3 Pa.s) was more stable than emulsions with lower viscosity. Emulsions with 0.75 wt% and 1.00 wt% CMF showed the same results as emulsions with 0.50 wt% CMF dose. As in the last case, before centrifugation, the emulsions with the highest \(\mu_{\mathrm{a}}\) and around 65% OCEP showed a high number of small droplets and a regular shape, with CMF homogeneously distributed among them. After centrifugation, the emulsions did not present phase separation in the test tubes, and the droplets diameters were maintained with values between 3 and 100 \(\mu\)m (0.75 wt% CMF) and from 3 to 60 \(\mu\)m (1.00 wt% CMF). These emulsions were considered stable. On the other hand, emulsions with an OCEP lower or higher than 65% showed heterogeneous CMF dispersions before and after centrifugation, with a high deformation of the droplets after centrifugation and a \begin{table}
\begin{tabular}{c c c c c} \hline
**CMF Dose (\%)** & \(\mu_{\mathrm{a}}\) **Max (Pa-s)** & **OCEP (\%)** & **EI (\%)** & **O/W Ratio** \\ \hline
0.25 & 5.1 & 73.8 & 54.2 & 40/60 \\
0.50 & 6.3 & 65.8 & 60.8 & 40/60 \\
0.75 & 9.1 & 62.9 & 79.5 & 50/50 \\
1.00 & 8.2 & 67.8 & 88.5 & 60/40 \\ \hline \end{tabular}
\end{table} 
Table 2: Summary of emulsions with the highest \(\mu_{\mathrm{a}}\) for each CMF dose. mixture of oil and water phases. These emulsions were considered unstable. Among these unstable emulsions, 50/50 O/W emulsion with 1.00 wt% CMF had an OCEP more close to 65% (58.8%); the emulsion had more homogeneous droplets and could be considered as a half-stable emulsion. Figure 8: Microscope images and test tubes for several CMF doses. In general, centrifugation did not affect the number and the shape of droplets when emulsions had around 65% OCEP and higher \(\mu_{a}\), with stable emulsions and no dependence on the CMF dose. In addition, droplets size had an order of magnitude of 10\({}^{-5}\) m, independent of CMF dose, stability, or OCEP. This finding is in agreement with the work by [PERSON] et al. [9], which examined droplet size of Pickering emulsions with milled cellulose.