## 3 Results and Discussion
### The Thermal Analysis of Powdered Biomass of Rhodotorula glutinis var. rubescens  
In the DSC diagrams of the red yeast biomass after cultivation for 48, 72, 96, 120, and 144 h, two small and mild peaks were identified (Figures 2-8). The peaks were endothermic. The course of third endothermic peaks were observed as distinct and sharp shapes, as shown in Figures 2-6. The maximum temperature of the first endothermic peaks was observed from about \(-1.10\) to \(-3.26\)\({}^{\circ}\)C for all the samples. The low peak maximum temperature indicated the presence of fat in yeast biomass. It is perplexing to compare the findings obtained in this study due to the scarcity of published data on the thermal analysis of powdered yeast biomass. The DSC curves of cocoa powders were obtained with mild, similarly endothermic peaks at temperatures of about 0 \({}^{\circ}\)C, regardless of the heat treatment type used for beans [27]. However, the thermal analysis of extracted lipid (not powdered biomass) from _Rhodotorula mucilaginous_ obtained crystallization DSC curves with two exothermic peaks [28], and the second peak was characterized by a temperature of about \(-17\)\({}^{\circ}\)C. Red yeast biomass contains unsaturated fatty acids, and its characterized melting temperature is below 0 \({}^{\circ}\)C. The next sharp peaks, which were observed at temperatures ranging from 157.70 to 168.04 \({}^{\circ}\)C, were associated with the presence of low molecular weight carbohydrates. The third sharp, distinct peaks, (maximum temperatures were noticed within the range from 199.21 to 213.69 \({}^{\circ}\)C), were associated with the presence of crystalline sugars, which may indicate the accumulation of trehalose by the yeast. [PERSON] and [PERSON] [29] investigated dehydrated trehalose and observed three sharp endothermic peaks in the DSC curve. The third peak was characterized by the highest maximum temperature of about 210 \({}^{\circ}\)C, which was found to be associated with the transition of the \(\beta\) form of trehalose. Figure 1: The content of lipid (blue), protein (red), sugar (grey), and other components (orange colour) in the biomass of _Rhodotorula glutinis_ var. _rubescens_ during the glucose fed-batch cultivation at 20 \({}^{\circ}\)C in potato wastewater medium. The content of other components was calculated as 100% d.w.—sum of lipid, protein, and sugar content (% d.w.). Figure 4: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 96 h cultivation in glucose fed-batch in potato wastewater. Figure 3: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 72 h cultivation in glucose fed-batch in potato wastewater. Figure 2: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 48 h cultivation in glucose fed-batch in potato wastewater. Figure 5: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 120 h cultivation in glucose fed-batch in potato wastewater. Figure 6: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 144 h cultivation in glucose fed-batch in potato wastewater. Figure 7: The DSC curves of powdered biomass of _Rhodotorula glutinis_ var. _rubescens_ after 168 h cultivation in glucose fed-batch in potato wastewater. The DSC diagrams of red yeast biomass after 168 and 192 h of cultivation in Figures 7 and 8 were presented and characterized in a different course than the previous ones. The first endothermic peaks were observed at \(-\)3.53 and \(-\)3.82 \({}^{\circ}\)C in Figures 7 and 8, respectively. These results indicate the presence of fat in the cells of red yeast. The second endothermic peak was characterized by a mild course at maximum temperatures of about 59.46 \({}^{\circ}\)C in dry biomass from the 7 th day of incubation and 59.64 \({}^{\circ}\)C on the 8 th day.