## 3 Results and Discussion
### YBMCs Morphology  
Figure 2 presents SEM pictures of the NY and AY microstructures, as well as YBMCs obtained from them from each of the 3 oil blends. Micrograph analysis showed significant morphological differences between the yeast cells without oil charged inside and the final microcapsules. Strong aggregation of NY cells was observed (Figure 2A), which was characterized by an oval, bubble-like shape. After the autolysis process, irregularly shaped collapsed bubbles were formed (Figure 2B). After the encapsulation process, the resulting capsules were mostly spherical, with the exception of RBWg/NY and REp/NY, whose shape was irregular. Literature data show that the aggregation of yeast cells is caused by a high content of \(\beta\)-glucans [46]. A strong agglomeration of microcapsules was also observed, especially in the case of NY capsules. Also, [PERSON] et al. [24] observed similar agglomeration behavior for fish oil containing YBMCs. The reduction of YBMCs agglomeration due to cell autolysis increased the outer surface of the microcapsules and, consequently, the encapsulation efficiency. Therefore, preventing the aggregation of yeast cells in order to increase the diffusion rate of the encapsulated material into the YBMCs is recommended.  
The size of yeast shells is important and determines their stability and microencapsulation efficiency. Small sized capsules are preferred as these make it easier to ensure uniformity and quality in food products [47]. The size distribution of YBMCs is presented in Table 3. The NY has uniform particle size distribution, as well as the obtained microcapsules (shown on Figure 3A). There is a noticeable shift towards higher values of the particle size distribution increasing after the absorption of oil during the encapsulation. In case of the AY, there is no uniformity in the particle size distribution. There is a wide range of different sizes of particles with local maxima (shown in Figure 3B). The autolysis process causes the removal of inside organelles from yeast cells and their partial disintegration, which can explain this characteristic of two sets of particle size distribution. Furthermore, autolysis does not impact every cell in the same way and usually leads to the limitation of cells aggregating and a more representative particle size distribution. On the other hand, the NY and NY-based microcapsules form aggregates (proven by SEM images), which can explain two separate maxima in the case of the AY samples and the uniform distribution of NY. Larger YBMCs provide better protection for the encapsulated material, but dissolve less well in the end products [48]. It has also been shown that the presence of large particles may be undesirable in most food products [49]. Capsules that are too small, however, can be empty containers that do not contain the encapsulated material inside [48].  
Figure 1: Effect of yeast cell pre-treatment on encapsulation yield. Statistically significant differences were marked by * (comparing NY with AY).  
Figure 2: \(Cont\).  
Figure 2: Scanning electron microscopic images of NY (**A**), AY (**B**), \(\mathrm{RBWg/NY}\) (**C**), \(\mathrm{RBWg/AY}\) (**D**), \(\mathrm{CRb/NY}\) (**E**), \(\mathrm{CRb/AY}\) (**F**), \(\mathrm{REp/NY}\) (**G**), and \(\mathrm{REp/AY}\) (**H**).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Oil Blends**} & \multicolumn{2}{c}{**NY**} & \multicolumn{2}{c}{**AY**} \\ \cline{2-7}  & **Dx (10)** & **Dx (50)** & **Dx (90)** & **Dx (10)** & **Dx (50)** & **Dx (90)** \\ \hline RBWg & 170.98 \(\pm\) 11.18 & 621.03 \(\pm\) 55.68 & 1520.72 \(\pm\) 184.96 & 77.70 \(\pm\) 2.30 & 261.86 \(\pm\) 22.27 & 1133.33 \(\pm\) 207.75 \\ CRb & 197.34 \(\pm\) 11.11 & 798.88 \(\pm\) 69.90 & 1958.45 \(\pm\) 126.62 & 77.56 \(\pm\) 1.63 & 305.88 \(\pm\) 22.25 & 1033.61 \(\pm\) 127.78 \\ REp & 172.72 \(\pm\) 17.01 & 780.38 \(\pm\) 79.21 & 2134.76 \(\pm\) 150.17 & 88.75 \(\pm\) 4.03 & 409.83 \(\pm\) 40.75 & 1743.94 \(\pm\) 230.84 \\ \hline \end{tabular}
\end{table}
Table 3: YBMCs size distribution in \(\upmu\)m.