## 3 Discussion  
Peanuts, a commercial oilseed crop, provide high-quality vegetable oil and a source of nutrients for the human diet. The metabolites of peanuts have attracted much attention in academic research and peanut production [17; 25; 26; 27; 28; 29; 30]. There are numerous peanut varieties, and the quality of peanut varieties promoted for use in current production varies greatly among the varieties not only in nutritional quality but also in sensory quality. In the present study, three varieties of peanuts (ZKH1H, ZKH13H, and CFD) with different morphologies (Figure 1A) were selected to reveal the volatile and nonvolatile metabolites via widely targeted metabolomics. ZKH varieties are the main peanut varieties grown in Guangdong, China. The ZKH1H and ZKH13H varieties have been popularized and planted in larger areas in recent years. The CFD varieties of peanuts are the peanut varieties that are traditionally grown in Heyuan city, Guangdong. A visual comparison indicated that the peanut grains of the CFD variety were longer and finer (Figure 1B-D). Peanut flavor is the most important characteristic influencing consumer purchase intentions, and this characteristic is highly dependent on the cultivar [30; 31]. The present study investigated volatile and nonvolatile substances in three peanut varieties via flavoromics techniques, which identified 417 non-VOCs and 55 VOCs in the peanut varieties. Furthermore, OPLS-DA was used to screen out the differential nonvolatile metabolites among the pairwise comparisons of ZKH1H, ZKH13H, and CFD. The KEGG pathways of the differentially expressed nonvolatile metabolites and volatile organic compounds (VOCs) were annotated. Two core metabolic pathways affecting the nonvolatile metabolites and one core metabolic pathway affecting the volatile metabolites were identified after obtaining the intersection. This study provides a basis for the study of volatile and nonvolatile compounds in different varieties of peanuts. Figure 8: Differential VOCs from GC-MS were enriched in distinct KEGG pathways by comparing each of the two groups. **(A)** ZKH1H vs. CFD, **(B)** ZKH1H vs. ZKH13H. Peanut seeds are rich in high-quality fatty proteins and contain eight essential amino acids [32], which are known to be the precursors of peanut flavor substances [33]. In the present study, the core differences between the nonvolatile metabolites in the comparisons accounted for the largest proportion of amino acids and peptides (Figure 4C,F,I). The following metabolic pathways unique to the ZKH1H vs. CFD, ZKH1H vs. ZKH13H, and ZKH13H vs. CFD comparisons groups were all metabolic pathways related to amino acid synthesis: arginine biosynthesis; ascorbate and Aldarate metabolism; glycine, serine and threonine metabolism; starch and sucrose metabolism; amino sugar and nucleotide sugar metabolism; aminoacyl-tRNA biosynthesis; and glyoxylate and dicarboxylate metabolism (Figure 5). Therefore, these findings suggest that the nonvolatile metabolites of these three varieties of peanuts are caused mainly by differences in amino acid metabolism. [PERSON] et al. discovered that different peanut genotypes result in different amino acid contents, which is an important factor in the formation of peanut flavor [34]. In addition, each amino acid type and amino acid content in different varieties of peanuts contribute differently to the development of flavor [35; 36]. Among them, aspartic acid and glutamic acid directly affect the typical flavor of peanuts [37]. Therefore, evaluating the nutritional value of protein amino acids in different peanut varieties can provide a reference basis for peanut variety selection, development, and utilization. In the present study, differences in the amino acid contents of the three varieties of peanuts may have contributed to their different flavors. Food flavor is the aroma of various volatile organic compounds produced in food.