## 3 Results and Discussion
### The Thermal Analysis of Powdered Biomass of Rhodotorula glutinis var. rubescens
The IT of lipids extracted from red yeast biomass was in a range of 0.438-0.416, which is similar to sea fruits such as sardines _Hyporhamplus unifusciatus_[47], largemouth bass _Micropertus salmonides_[48], or freshwater mullet _Mugil cephalus_[49]. The value of IT is naturally higher for milk and cheese [50], and some kinds of meat, such as veal, beef, lamb, and chicken [45; 51; 52]. On the other hand, some oils such as Camelina oil (_Camelina sativa_) [53], and rapeseed oil [54] are anti-thrombogenic, resulting in low SFA content. In some opinions, AI and IT provide clear evidence [55] and are the most commonly used. Other indices identify the quality of oil-rich food products, such as the h/H (hypoc-holesterolemic and hypercholesterolic) index, and the value of this is better when it is higher. It is characterized by the relationship between the sum of PUFA and cis-C18 and the sum of C 12:0, C 14:0, and C 16:0 [16]. The h/H ratios of the _Rhodotorula_ yeast oils (Table 2) were quite high: 5.252-5.547 in comparison to food products such as fish, shellfish, meat, and milk products [55]. However, the plant oils rich in PUFA, such as Camelina oil, can have a three times higher h/H value. The impact of highly unsaturated FA, as well as FAs that have a low degree of unsaturation, can be expressed by the unsaturation index (UI). However, it does not differentiate between n-6 and n-3 fatty acids. The values of UI red yeast's lipids acquired from different sources were 86.465 and 87.320, which were rather low compared to the extraordinarily rich in PUFA in some algae [56] or seaweed oils [57]. The nutritional value of dietary fat can also be described by HPI (the health-promoting index) first proposed in 2004 [58]. This index is an inverse of IA. Generally, food products, characterized by high values of HPI should be eaten more often as they are assumed to be more beneficial. This index was mainly used for dairy product research [58; 59; 60], which did not exceed the value of 0.7. It is worth stating that the values of HPI for oil extracted from red biomass were a few times higher (4.6-5) compared to dairy products. The Amino Acid Content and Nutritional Value of Protein of Rhodotorula glutinis var. rubescens Yeast Biomass  
The growth and reproduction of yeast cells are directly related to protein biosynthesis due to the number of their structural, enzymatic, and signalling functions. With the time of cultivation under the glucose limitation, the level of protein accumulation decreases gradually until the yeast cells enter the stationary phase and after entering the phase of stationary growth [61]. Similarly, under excess glucose, which promotes lipid synthesis, the content of protein decreases with time (Figure 1). However, the biomass of the red oleaginous yeast after 5 and 6 days of incubation directed for lipid biosynthesis still contained a large amount of protein (av. > 35% d.w.). The presence and appropriate content of all essential amino acids (EAA) determine the nutritional value of proteins in the diet. They cannot be synthesized from metabolic intermediates by humans or other vertebrates. Because the body cells lack the biochemical pathways synthesizing EAA (His, Ile, Leu, Lys, Met, Phe, Tre, Thr, Trp, and Val) must be supplied from a diet [62]. For the very first time, the content of individual amino acids including EAA in the biomass of the red yeast _Rhodotorula glutinis_ was determined, and the results are shown in Figure 9.  
A high content of glutamic acid (99 mg/1 g of protein), leucine (>77 mg/1 g of protein), and isoleucine (>66 mg/1 g of protein), followed by Ala and Asp, was observed in _Rhodotorula_ yeast protein. We did not observe significant differences between the samples dependent on the incubation time, except for glutamic acid. The determination of amino acids in the microbial protein was performed earlier, mainly because yeast cells can be used as SCP (single-cell protein). For instance, _S.