## 4 Conclusions  
The highest protein content was found in sample 3L when grown on brewers spent grain. Out of the 16 analyzed amino acids, larvae 3L exhibited the highest levels in 11 instances, including essential ones. Sample 2S with wheat bran had the significantly highest fat content (34.22 \(\pm\) 0.491%) compared with other samples. By analyzing the amount of fat in the larvae and in the substrate used, we did not find any significant dependence. Sample 3L exhibited a beneficial fatty acid composition, especially concerning omega-3 FAs and oleic acid. Sample 2L had the highest total content of PUPA (36.24%) and total content of SFA (24.15%), while sample 1L had the highest total content of MUFA (45.18%). The worst omega-6/3 FA ratio was detected in sample 1L with sprouted potatoes, while in the rest of the samples (2L, 3L, and 4 CL), the ratio was very close to the scientific recommendation of 1:4. Thus, the results showed that the amount of both FAs and AAs in the larvae depended on the substrate in which they were reared, but sample 3L was the leader in both AAs and FAs. We have also found that the substrate can have an influence on peroxides and volatile fatty acid content since, during cultivation and storage under analogous conditions, except for the monthly substrate, in sample 3L with the brewer's spent grain, a significantly higher amount of peroxides was formed. The short-term benefit of this study encompasses a better understanding of the dietary conditions of _T. molitor_ larvae and their interaction with the substrate, which can contribute to improving their breeding conditions and nutritional value. The long-term benefit entails the emergence of new opportunities for the efficient conversion of low-cost industrial by-products through  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Pervoide Value, mg** & **Volatile Fatty Acid Content, meq/kg of Fat** \\ \hline
1L & 0.1 \(\pm\) 0.0 a & 44.67 \(\pm\) 1.33 a \\
2L & 0.1 \(\pm\) 0.0 a & 39 \(\pm\) 1.0 a \\
3L & 14.87 \(\pm\) 0.3 b & 346 \(\pm\) 4.0 b \\
4 CL & 0.17 \(\pm\) 0.3 a & 43 \(\pm\) 1.0 a \\ \hline \hline \end{tabular} a.b. –means marked with different letters in the column (in the groups of larvae separately) differed significantly (\(p<0.05\), [PERSON]’s LSD criterion). 1L—larvae (wheat bran + brewer’s yeast + green potatoes); 2L—larvae (wheat bran + brewer’s yeast + carrot); 3L—larvae (brewers’ spent grain + brewer’s yeast + carrot); 4 CL—larvae, control (wheat bran + brewer’s yeast + agar–agar gels).  
\end{table}
Table 5: Peroxide value and volatile fatty acid content in lyophilized larvae, \(n=3\).  
the utilization of _T. molitor_. However, for future research, it should be taken into account whether the growth of _T. molitor_ larvae under specific conditions creates opportunities for the formation of toxic elements and the reproduction of pathogenic microorganisms. Also, the exact source of peroxide formation should be found out in order to prevent its formation in the future.  
Conceptualization, D.A. and A.J.; methodology, E.M. and V.A. software, A.J.; validation, A.K. and E.B.; formal analysis, A.J.; investigation, A.J.; resources, S.K.; data curation, A.J., E.M., V.A., P.Z. and G.Z.; writing--original draft preparation, A.J.; writing--review and editing, A.J., E.B. and A.K.; visualization, I.J.; supervision, D.A. and A.K.; project administration, A.K., G.Z. and E.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
We would like to extend our gratitude to [PERSON] for her valuable consultations and significant assistance in handling statistical analyses.  
Author [PERSON] was employed by the company \"Divaks\". The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.