## 1 Introduction  
The growing number of people in the world, climate change caused by environmental pollution, and the dynamically changing geopolitical situation influencing the food supply chain require the search for environmentally and economically friendly food production technologies. This applies to both plant products given soil eutrophication, droughts, or floods ruining crops, as well as animal products (competition in the use of fields for the cultivation of fodder and food plants, emission of greenhouse gases, unethical). Microbial fat and protein can be valuable products for the food industry. The idea of using microorganism biomass as a source of protein (SCP) [1,2] or fat (SCO) [3] is not new, but it has recently become more realistic, especially when it meets the requirements of modern technologies. Biotechnological processing is certainly faster, and more environment-friendly compared to standard oilseeds, high-protein crops, or animal breeding. Components of the biomass of many species of fungi and unicellular algae are already used in practice as a source of protein, including spirulina and other bioactive compounds. And their fat, rich in polyunsaturated fatty acid, is used to supplement milk replacers or feed [4, 5, 6].  
_Rhodotorula_ spp. is red oleaginous yeast, the cells of which are able to accumulate lipids (>20% d.w.) [7]. The composition of fatty acids influences the intended use, so if the goal is to produce biodiesel, there should be a high proportion of SFAs. Then the final product has appropriate properties, such as cetane number (CN), flash point (FP), and viscosity (\(\mu\)) [8]. If SCO has a nutritionally proper fatty acid content, it can be used for food production [9]. The similarity of the fatty acid composition of red yeast lipids to valuable vegetable or fish oils predisposes them to be profitable as a food ingredient. Previous research showed that strain _Rhodotorula glutinis_ var. _rubescens_ can grow efficiently (biomass yield 39.52 g L\({}^{-1}\)) in deproteinated potato wastewater and glucose medium [8], and after fed-batch cultivation, the content of lipids in biomass exceed >34% d.w. [10]. Except for accumulated fat in intracellular lipid droplets, the cells are also rich in proteins, carbohydrates, and carotenoids [11]. These valuable substances are post-extraction residues and should be utilized following the zero-waste policy. The comprehensive management of biomass, without the need to extract or separate individual substances, as is the case with fodder yeast or dried or flaked baker's yeast, can be another concept. Because protein constitutes a large share of oleaginous biomass, the analysis of its composition should allow us to determine its nutritional suitability. After the cultivation process, the wet biomass is separated from the medium and then dried or lyophilized for storage or lipid extraction. The temperature influences the phase transitions and chemical reactions, so the thermal properties of biomass are valuable for processing. Differential scanning calorimetry (DSC) can be used to determine qualitative parameters, as well as the parameters of certain types of phase transitions (e.g., melting and crystallization) and oxidative stability of lipid-rich samples [10,12]. Regardless of the next technological steps after the cultivation of red yeast, the quantitative and qualitative characteristics of biomass components are necessary for the prediction of the nutritional properties.  
This study focused on the thermal characterization of dried oleaginous yeast biomass in terms of lipids and proteins and their characteristics, including the nutritional characteristics. Such research has not been conducted so far.