## 4 Conclusions  
The thermal as well as quantitative and qualitative characteristics of _Rhodotorula_ yeast cell biomass after cultivation in lipid-promoting biosynthesis conditions were determined. The differential scanning calorimetry diagrams of red yeast biomass revealed two small and mild endothermic peaks where the first indicated the presence of fat in yeast biomass \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{3}{*}{**Amino Acid**} & \multirow{3}{*}{**FAO/WHO Standard**} & \multicolumn{3}{c}{_Rhodotorula glutinis_} \\  & & **var. rhbescens** & \\  & & **mg/g** & **CS** & \\  & & **120 h** & **144 h** \\ \hline Cys & 6 & 149.1 & 124.2 \\ His & 15 & 302.8 & 302.3 \\ Ile & 30 & 220.6 & 220.4 \\ Leu & 59 & 125.0 & 124.8 \\ Lys & 45 & 40.5 & 40.3 \\ Met & 16 & 80.4 & 82.8 \\ Met + Cys & 22 & 99.1 & 94.0 \\ Phe + Tyr & 30 & 192.0 & 185.9 \\ The & 23 & 135.7 & 135.3 \\ Val & 39 & 79.1 & 78.9 \\ \hline EAAI & & 123.5 & 120.4 \\ \hline \hline \end{tabular} CS—chemical score (CS = (ai/as) \(\times\) 100; ai—concentration ratio of the restrictive amino acid; as—concentration of this amino acid in the standard; EAAI—Essential Amino Acid Index.  
\end{table} 
Table 3: The comparison of _Rhodotorula glutinis_ var. _rubescens_ biomass to standard protein. and the melting temperature indicated its composition of unsaturated fatty acids. The next small peaks were associated with the presence of low molecular weight carbohydrates, and the third distinct peaks were associated with the presence of crystalline sugars, indicating the presence of trehalose. However, the thermal characteristic of biomass originating from the last days of cultivation revealed additional peaks, suggesting the denaturation of protein, and the shape of the last peak indicated the presence of a mixture of saccharides rather than one crystalline sugar. DSC was successfully used to determine the melting behavior of the dried biomass of _Rhodotorula sp._ and indicated the presence of lipids, sugars, and proteins. The oleic, palmitic, and stearic acids were predominant, resulting in a high MUFA concentration in the biomass. According to the fatty acid composition as well as amino acid content, the nutritional properties and healthy factors were calculated. Similarly to other yeast strains, _Rhodotorula_ yeast protein was characterized by a high content of glutamic acid. However, the order of amino acid contributions appears to be species-specific and depends on the carbon source. The value of the essential amino acid index of the proteins present in the red yeast biomass suggested a superior amino acid composition compared to the FAO/WHO standard. Despite the high EAAI, yeast protein is characterized by a small content of Lys or Met. However, the amount of lysine was higher than that in some cereals, such as maize, millet, or sorghum. The nutritional characteristics of lipids extracted from _Rhodotorula glutinis_ var. _rubescens_ revealed better quantity compared to dairy products when atherogenicity, thrombogenicity, and health-promoting index, as well as the PUFA/SFA ratio, were taken into account. The ratio n-6/n-3 of the studied fat was adequate for recommendation. However, the lack of long PUFA does not entitle us to conclude that lipids obtained from red yeast without modification can be an alternative to fish oil. After the extraction of the microbial lipids, post-extraction waste remains. Post-extraction wastes contain protein, sugar (e.g., polysaccharides of the cell wall and trehalose), and other components, e.g., vitamins, that are not extracted into solvents along with lipids. We considered the usefulness of the protein residue after lipid extraction theoretically (based only on calculations). Nevertheless, during the extraction procedure, unfavourable changes may occur, affecting the amino acid composition and nutritional value of the protein, such as digestibility or bioavailability. In further work, the potential of post-extraction residues as food or feed additives usage should be tested in practice.