## 3 Results and Discussion
### Thermal Oxidative Stability of YBMCs  
Oil blends with a \(\omega 3/\omega 6\) ratio of 5:1 are characterized by a large amount of unsaturated fatty acids (the sum of MUFA and PUFA is about 90%) and thus are very susceptible to oxidation. Many different factors affect oxidative stability, including resistance to oxidation caused by atmospheric oxygen, temperature, light, metal ions, etc. In these tests, the oxidative stability of the oil blends and the plasmolyzed and non-plasmolyzed YBMCs within the oils were assessed by DSC and TG measurements.  
The high content of unsaturated fatty acids determined by chromatography (Table 2) within the oil blends used for encapsulation was confirmed by the curves of the softening characteristics of oils, determined by the DSC method (Figure 5). According to the literature data, the low temperatures of endothermic peaks are responsible for PUFA, and their content is higher in relation to the lower value of the endothermic recorded during the analysis [53; 54]. The DSC melting curves of edible fats have different peak temperatures. Triacylglycerlycerols containing unsaturated fatty acids in their structure are characterized by negative maximum peak temperatures (Figure 5). It proves the content of MUFA and PUFA in triacylglycerols of the tested oils [55]. In Figure 5, no endothermic peaks were observed; the maximum temperature would have had positive temperature values.  
The DSC curves of native and autolyzed yeast (Figure 6A) indicate that NY shows an endothermic peak at about 61 \({}^{\circ}\)C, corresponding to the phase transition temperature of yeast cell phospholipid bilayers. The phase transition temperature of yeast depends on many factors, such as the temperature during their breeding, the microbiological medium used, or the method of aeration of the culture, but it depends also on the growth phase in which the yeast was collected and in the published works of other authors, different values were assumed [19; 43]. In contrast to NY, AY, due to the liquefaction of the cell membrane caused by the autolysis process, saw only a slight phase transition at a temperature of about 55 \({}^{\circ}\)C, which is consistent with the decrease in this temperature after yeast cell lysis, described by other authors [51]. The encapsulation of oils in yeast cells is evidenced by small peaks with maxima in negative temperatures (Figure 6B). In the yeast figures, small endothermic peaks are present only for NY yeast, with positive temperatures of about 50 \({}^{\circ}\)C (Figure 6A). The presence of this peak may indicate the degradation of proteins (peptides). The peaks of temperature, which are in the range of positive temperatures, indicate the melting of carbohydrates.  
Figure 4: FT-IR spectra of capsules.  
Figure 5: DSC melting curves of oil blends used in encapsulation process.  
Figure 6: DSC curves of empty NY and AY (**A**), as well as YBMCs (**B**).  
Changes in the course of the DSC curves for NY-based YBMCs are more pronounced. Endothermic peaks characterized by maximum temperatures at sub-zero temperatures indicate the presence of oils in the yeast capsules. In addition, the temperature values confirm the presence of triacylglycerglycerol, the structure of which contains mono and polyunsaturated fatty acids. A decrease in the temperature of the endothermic reaction was observed, which may result from the integration of the encapsulated oil with the yeast bivalent lipid, which led to an easier transition from the gel to the liquid crystal state. van der Walls interactions between the oils and the cell membrane led to the reduction of its cohesiveness and, consequently, to its liquefaction [19]. At the same time, in the case of AY without and with encapsulated oils, an endothermic peak shift towards higher temperatures was demonstrated. As indicated by [PERSON] et al. [51], such changes may indicate an increase in the thermal stability of the encapsulated oil.