## 1 Introduction
These oils can serve as sustainable alternatives to palm oil. Modifying oleaginous yeast to increase its production of saturated fatty acids can make its lipid profile more similar to palm oil [16]. Microbial oils could help preserve forests and reduce greenhouse gas emissions linked to palm oil production [17]. An economic analysis indicated that microbial oil production is more expensive than vegetable and animal lipids. This is primarily due to the high cost of glucose, a basic carbon source in microbial culture, which accounts for 80% of the raw material cost. Nevertheless, using agricultural and industrial waste in culture media can potentially reduce costs and enhance the economic viability of bioproduction [18]. Oleaginous yeast show potential in biodiesel and oleochemicals production, with better results than microalgae or vegetable oils. The rapid growth rate of yeast, replicating in less than an hour, gives it a competitive advantage over microalgae. It has been estimated that producing 1000 tonnes of refined oil and 1800 tonnes of dry whey yeast and protein blend by continuously fermenting the whey for 250 days a year would cost $2.8 million and provide a 14% internal rate of return. Other evidence suggests that producing microbial oil from yeast or fungi would cost more than US$3/kg in 2008. However, no detailed studies in the open literature estimate the cost of producing microbial oil [19]. Despite the many advantages of microbial oil production in yeast cells, work is still needed to increase the economic viability of this process on a commercial scale. The high cost of SCO biosynthesis lies in the price of culture and intracellular lipid extraction. The first cost can be reduced by using waste culture media, and the second by developing a way to use microbial oil without extracting it. This paper addresses both of these aspects. The utilisation of _Y. lipolytica_ yeast in the production of lipids from low-quality waste material, with a concomitant examination of the impact of the type of water employed in culture (distilled versus tap water), signifies the innovation of the research presented. The waste, although often treated as a problem, is at the same time a rich source of energy and carbon that can be used in biotechnological processes to produce biomass, lipids, or other high-value-added products. This study aimed to obtain oleaginous yeast _Y. lipolytica_ biomass rich in storage lipids in a nitrogen-limited culture medium with a waste carbon source and untreated tap water. The resulting lipid-rich biomass was characterized to evaluate its nutritive quality, which is important for its application in food technology, including microbial lipids' oxygen stability and composition. To the best of the authors' knowledge, the biomass of unconventional yeast has been studied as a source of protein in the human diet and animal nutrition. Preparations of cell walls, valuable glucans, and mannans are also being studied. The current research is being conducted on storage lipids as an alternative to vegetable oils. The biomass of oleaginous yeast containing more than 20% fat in the cell's dry weight was discussed as a possible raw material in food technology. Previous work evaluated the safety of the oil in terms of polycyclic aromatic hydrocarbons (PAHs), the residual content of the solvent used to extract fat from yeast cells and the presence of heavy metals [20]. Because only the protein-rich biomass of _Y. lipolytica_ has been allowed for human nutrition by EFSA, the research presented in this paper might give new insights into the nutritive properties of the high lipid-content yeast biomass. This research highlights the importance of microbial oil as a food additive. Since only biomass of _Y. lipolytica_ is currently approved for human nutrition, our study provides new insights into the nutritive properties of the high lipid-content yeast biomass and offers data that may support future regulatory approval for using microbial oil as a food additive.