## 4 Discussion  
The metabolite profile obtained using the proposed analytical protocol is described and discussed for this class of compounds, combining the results obtained using the different methodologies and carrying out, when possible, a comparison with reported literature data. _Amino acids and derivatives:_ Among the nineteen amino acids identified and quantified by means of NMR, alanine and proline were shown to be the main amino acids, whereas methionine was present in the lowest concentration. All the nine essential amino acids were present, confirming the important nutritional value of edible crickets. Moreover, it is noteworthy that the NMR amino acid quantification here refers to the free amino acids naturally present in the matrix, without any protein hydrolysis. In contrast, previous studies carried out on _A. domesticus_ powder [8; 9] have reported the amino acid content obtained after protein hydrolysis, making a direct data comparison not possible. FT-ICR MS allowed us to also detect arginine and to reveal the presence of dipeptides (cysteineyl-methionine, methionyl-methionine, methionyl-tyrosine) and tripeptides (valyl-arginyl-tyrosine, methionyl-leucyl-phenylalanine, arginyl-prolyl-proline). _Organic acids:_ Acetate, formate, fumarate, lactate, and succinate were identified and quantified by means of NMR spectroscopy, with formate being identified in house crickets for the first time. From a quantitative point of view, lactate was the most abundant metabolite of the series, whereas fumarate was measured in the lowest concentration (365 times lower than lactate). Comparing these data with the results previously obtained for _A. domesticus_ powder [12] using GC-MS analysis, it is possible to observe both similarities and differences. In particular, succinate and lactate were present in the same concentration range in both studies, whereas fumarate and acetate were shown to have different behavior. In the case reported here, fumarate was the organic acid present at the lowest acid concentration (1.87 mg/100 g), whereas in the cited paper, fumarate has been reported as the more representative acid, with a concentration 685 times higher than the one reported here, with acetate being present at the lowest concentration. Moreover, in the _A. domesticus_ powder investigated here, formate was also detected, whereas [PERSON] at al. reported the presence of ascorbate. FT-ICR MS analysis allowed the detection of ethyl-malate, a derivate of succinic acid, and sebacic acid in the hydroalcoholic extract, whereas gluconic acid was revealed in both extracts. _Fatty acids:_ Lipids in household crickets are found in the form of triglycerides stored in adipocytes, which, along with glycogen, are a relevant energy reserve and represent a largely studied class of molecules in this matrix. The GC-MS analysis of the derivatized sample of cricket powder allowed us to determine the fatty acid content, with linoleic acid and palmitic as the most abundant, followed by oleic, stearic, linoleic, and pentanoic acids. Our results are in accordance with the literature data [8; 11]. The same fatty acids were also detected by means of FT-ICR MS analysis. Moreover, considering the higher sensitivity of this technique, further putative formulas of fatty acids were identified, namely lauric, myrsitic, and palmitoleic. Several classes of fatty acid derivatives, namely amide (palmitamide, oleamide, linoleamide, stearamide) and ester (palmitoylcarnitine and stearoylcarnitine) derivatives, were also revealed, together with some hydroxy fatty acids (hydroxy-linoleic and hydroxy-linoleic acids), well known for their anti-inflammatory, antioxidant, and anti-diabetic properties [24]. Due to a possible ion-suppression effect and variations in the signal response, ESI MS is not able to offer an accurate quantitative analysis.