## 3 Results and Discussion
### Volatile Compounds Analysis
The presence and concentration of these alkanes can be influenced by several factors, including the degree of lipid oxidation, the composition of fatty acids in the raw material, and the specific processing parameters such as temperature, humidity, and the duration of curing [51; 52]. For instance, extended curing times and higher temperatures can enhance lipid oxidation, leading to an increasedformation of alkanes. Although the alkanes are not primary contributors to the aroma due to their high odor thresholds, their presence serves as an indicator of the extent of lipid oxidation and can reflect the oxidative stability and quality of the ham. Therefore, monitoring the levels of specific alkanes can provide valuable insights into the processing conditions and potential shelf-life of dry-cured hams. In this study, 15 ketones were detected, which are generally derived from lipid oxidation, amino acid degradation, and the Maillard reaction [38; 53; 54]. These compounds contribute to the fatty aromas associated with cooked meat [55; 56]. Among the detected ketones, dihydro-5-pentyl-2(3H)-furanone (D6) and 5-butyldihydro-2(3H)-furanone (D8) were present in all ham samples at relatively low concentrations. 2-Heptanone (D1) and 2-nonanone (D2) were the most and second most abundant ketones detected in BHCH (1291.03 \(\pm\) 3.03 ng/g and 975.78 \(\pm\) 3.48 ng/g, respectively) and were also found in SXZH (979 \(\pm\) 2.68 ng/g and 1166.89 \(\pm\) 2.24 ng/g, respectively). These two ketones are also present in Istrian dry-cured hams [57]. Notably, 2-Heptanone (D1) contributes to the dry-cured ham aroma with spicy/blue cheese/acorn sensory notes, whereas 2-nonanone (D2) contributes to ham aroma with floral/fruity/blue cheese aroma. 3-Octanone (D3), unique to BHCH (839.6 \(\pm\) 1.95 ng/g), likely originates from roscenary used in the production process and aligns with findings in Istirian dry-cured hams [6; 58]. Acetophenone (D11) was detected in the two Xuanwei hams (187.88 \(\pm\) 4.51 ng/g in SXZH and 70.65 \(\pm\) 1.00 ng/g in FXZH), indicating its association with long-ripened raw hams [48] and distinguishing Xuanwei from non-Xuanwei hams. Seven esters were detected, formed by the esterification of various acids and alcohols. Esters typically increase with a longer ripening process [39; 59; 31] and impart fruits and sweet notes to dry-cured hams. The contribution of esters to the overall aroma depends on the length of their chain [60; 35; 61]. Esters formed from short-chain acids provide fruits notes while long-chain acids impart fat odors [62]. The relatively low amounts of esters in this study may be attributed to the antimicrobial activity of sodium chloride during the long curing period [37; 63]. Despite the overall low concentrations, substantial differences were observed among the ham types. SXZH exhibited the highest diversity and abundance of esters, including octanoic acid ethyl ester (E1) (499.38 \(\pm\) 3.79 ng/g) and butanoic acid 3-methyl ethyl ester (E2) (370.83 \(\pm\) 4.09 ng/g), which are known to impart fruits and fermented notes. FXZH also showed high levels of hexanoic acid ethyl ester (1207.78 \(\pm\) 0.79 ng/g). In contrast, BHCH and LTWH presented no detectable esters, and only trace amounts were found in FXWH. These differences may reflect variations in microbial activity, enzymatic hydrolysis, and raw material properties among the products. In particular, the extended aging time and potentially more diverse microbial ecosystem of SXZH could favor the formation of esters [64; 65]. Moreover, the absence of detectable esters in BHCH might be linked to its tightly controlled ripening environment and higher salt content, which can suppress microbial fermentation pathways essential for ester generation [66; 67].