## 3 Results and Discussion
### The Thermal Analysis of Powdered Biomass of Rhodotorula glutinis var. rubescens
cerevisiae_ biomass contained a high percentage of protein (55.19%), characterized by the high content of Lys, Leu, Asp, Glu, and Ile [63]. The major component of biomass _S. cerevisiae_ enriched in Cu, Fe, and Mn were glutamic acid (>45 g/kg), aspartic acid (av. 37 g/kg), and lysine (31-34 g/kg). On the contrary, the lowest concentration was observed for cysteine and methionine (<5 g/kg) [64]. The amino acid composition of dried yeast biomass after beer production [65] also showed the highest content of glutamic acid (5457 mg/100 g), lysine (4541 mg/100 g), and aspartic acid (4150 mg/100 g). The analysis of amino acid content in the biomass of _Candida utilis_[66] showed that glutamic acid (15.5 g/100 g) and aspartic acid (8 g/100 g) leucine (7.12 g/100 g) accounted for the largest share in cell protein. The following, alanine, valine, and lysine should be mentioned, as these exceeded 5 mg/100 g. The smallest amount was observed for methionine 1.58. Lysine limits the value and quality of protein in animal feeding considering the physiology of digestion, so protein rich in Lys may prove to be excellent in the development  
Figure 9: The content of individual amino acids (mg/1 g of protein) in biomass of _Rhodotorula glutinis_ var. _rubescens_ yeast after 120 h (blue) and 144 h (orange) of cultivation. The superscripts * go for essential amino acids. Ala—alanine, Arg—arginine, Asp—aspartic acid, Cys—cysteine, Glu—glutamic acid, Gly—glycine, His—histidine, Ile—isoleucine, Lys—lysine, Met -methionine, Phe—phenylalanine, Pro—proline, Ser—serine, Thr—threonine, Val— valine. a–j were added only for significantly different values (ANOVA). of feed. The content of lysine in the protein of crustaceans such as _M. macrocopa_ and _Simoccephalus vetulus_ was successfully increased by adding red yeast biomass to zooplankton [67]. However, the authors did not reveal the amino acid content of the biomass used. Our research showed that 1 g of protein of _Rhodotorula glutins_ yeast contains 18 mg of Lys (Figure 9). [PERSON] and [PERSON] introduced a chemical score index in the forties of the past century [21]. It is a useful factor for the compartment of any protein with the reference pattern, according to the essential amino acid content. The limiting amino acid is the one that occurs in the smallest amount relative to the reference protein. The FAO/WHO developed a reference protein, a complete protein containing all EAA, for the first time in 1973 [68], and changed some recommendations later. The latest testimonials were identified in 2007, reducing the requirements for Phe [69], and in our study, we used this recommendation to calculate the chemical score. The examined red yeast biomass was distinguished by a high value of the chemical score for His, Ile, Leu, the sum of Phe, Tyr, and Thr (Table 3). Proteins haveh a high nutritional value when they haveh a balanced amino acid composition expressed by a high value of the essential amino acid index. A promising value of EAAI (Table 3) was achieved for the protein obtained from the biomass of oleaginous red yeast. This suggests that the amino acid composition is superior to that of the FAO/WHO standard. However, despite higher EAAI, the projected diet based on yeast protein would not be satisfactory in terms of the content of some essential amino acids. Disadvantagously, they were all limiting in Lys and Met, with chemical scores lower than the standard. Notwithstanding, the amount of lysine is higher (1.8%) than that of cereal proteins, where the content is 0.31% (maize), 0.21-0.28% (millet), or 0.24% (sorghum) [70]. The essential amino acid composition of _Saccharomyces cerevisiae_ shared from the largest to the smallest of the individual EAA was Leu, Lys, Arg, Val, Thr, Ile, Phe, His, Tyr, Met, and Cys. The EAAI of _S. cerevisiae_ was approx. 67% for both strains [71]. The oleaginous yeast strain _Yarrowia lipolytica_ can also be a valuable source of protein.