It is projected that the world's population will reach nearly 9.8 billion people by 2050 [7], and if agricultural systems remain as they are now, the production of edible crops would need to increase by 119% [8]. Consequently, environmental sustainability concerns underscore the importance of developing alternative protein strategies, including new sources of high-quality proteins and fats [9]. In scientific sources, there is a lot of published information about the high protein percentage in mealworm larvae [10]. However, to determine the quality of proteins, it is important to consider the concentration of each AA [11]. When choosing a substrate for growing mealworms, it is important to consider the composition of AAs because it can influence the growth rate and productivity of the larvae [10]. Meanwhile, the AAs composition of mealworms is important for humans in several key ways, such as health and nutritional value [12]. Essential AAs are important for both human and animal nutrition and health because the body cannot produce them and must obtain them through food [13]. [PERSON] et al., while rearing mealworms on traditional substrate (wheat bran), have found that the composition of AA meets the needs of not only domestic animals but also humans. In general, concentrations of lysine and threonine were higher, but lower amounts of methionine and cysteine were found in mealworms [14]. Another study conducted by [PERSON] et al. showed that by choosing a substrate that is characterized by a high protein content and a suitable amino acid composition, the total protein content increases (70.9-74.1% dry weight), while the fat content decreases analogously [10]. Indeed, the drying method can also influence the composition of amino acids, as it was noted by [PERSON] and [PERSON] that mealworm larvae dried in the sun and oven had higher levels of essential AA compared to lyophilized ones [15]. The composition of FAs in mealworms is important for several reasons, first because it influences the nutritional value [16]. Various FAs have different nutritional properties, and their presence in food can affect human health. For example, omega-3 FAs, found in fish, flaxseeds, and nuts, are known for their beneficial effects on heart health [17]. It is known that excessive consumption of saturated fatty acids (SFA) can increase the risk of heart and cardiovascular diseases, whereas unsaturated fatty acids can be beneficial for health [18]. [PERSON] et al. studied the variation in fatty acid composition in _T. molitor_ larvae depending on the substrate used [19]. They have found that despite the different fat content of the six different rearing substrates used, the fat content of _T. molitor_ larvae was similar (>34% larvae). The results of the mentioned authors showed that the composition of FAs differs in larvae grown on different feeding substrates [19]. However, regardless of the nutritional value, it is equally important to monitor the formation of chemical toxins that can have a negative impact on human health [20]. Although the majority of chemical toxins, including biogenic amines, polycyclic aromatic hydrocarbons, heavy metals, glycoalkaloids, pesticides, etc., have already been examined and the results were published by the authors, it is necessary to pay attention to peroxides and volatile fatty acids, which have not been studied yet using these by-products [21]. The larvae primarily consume organic materials, which are converted into energy and other substances during digestion [22]. Various compounds are formed during digestion, including fatty acids, which may be classified as volatile compounds. The FAs may result from lipid breakdown processes within the larvae's bodies or may be produced by microbial activity that affects organic materials present in the larvae's food or digestive tract [23]. Therefore, volatile compounds can originate as by-products of larval digestion or as a result of microbial metabolism.