## 2 Results and Discussion
### Volatile Compounds
#### 2.2.2 Alcohols  
The identified alcohols, linear and branched, were the most abundant volatiles because they are among the main lipid oxidation products. The methyl branched alcohols can also be derived from the Strecker degradation of amino acids. It is known that branched alcohols originate from microbial degradation of the respective branched aldehydes [22]. Thus, the formation and release of branched alcohols is affected by the salting conditions due to the antimicrobial activity of NaCl. Thus, a higher production of branched alcohols is observed when NaCl is partially replaced by other formulations [23].  
The highest concentration of total alcohols was found in BF muscle (11.27 mg/kg) while the lowest concentration corresponded to SM (8.56 mg/kg). 3-Methyl-1-butanol was by far the most abundant alcohol in the three muscles. The high concentration of 3-methyl-1-butanol (_i.e._, 3.10 mg/kg in BF) can be due to the activity of the microorganisms present in the ham. Microorganisms can act on 3-methylbutanal formed by Strecker degradation of amino acids during proteolysis to give rise to 3-methylbutanol [24]. The alcohol with the highest concentration in SF was hexanol. In SF, where lipids mean 89.7% [25], most of alcohols are produced by lipid oxidation and the proteolysis mechanism does not occur at great extent.  
Because of the high OT of some alcohols (2-propanol, ethanol, 2-methyl-3-buten-2-ol, 2-mehyl propanol, 2-butanol, and nonanol) in comparison with their concentrations (Table 2), their impact on aroma has been considered minor [26]. Table 2 also shows that, in general, alcohols contribute to hamflavor with herbaceous, woody and fatty notes [27]. 3-Methyl-1-butanol has a significant sensory impact and it is a marker of Iberian hams because its high concentration in these hams compared to other breeds. The contribution of this compound to aroma depends on its concentration as it varies from green [8] to dried fruits, and particularly to acorns in the case Iberian hams (Table 2). Another odor compound whose concentration is higher in Iberian hams is hexanol, which contributes to fruity-green odor perception. Its concentration in the SF is mostly responsible of its odor perception. Among the alcohols which contribute to aroma, pentanol and 2-heptanol, for instance, would not be able to distinguish between non Iberian and Iberian hams (\(p<0.05\)). The low odor threshold of 1-octen-3-ol indicates that it contributes with a strong mushroom aroma (Table 2) to almost all the hams. The concentration of this compound significantly rises as the amount of curing salt increases [28], which may explain the differences between samples.  
The study of the relationship between alcohols and amino acids showed that there was much more relationship between them in non Iberian than in Iberian hams. The values of the adjusted-R\({}^{2}\) when regressing both data sets were lower in the former, with the exception of 2-butanol from ST with histidine (0.96). On the contrary, high correlation values between the concentrations of amino acids and volatiles were observed in Iberian hams because the increase of free amino acids in long-processed hams [11]. Thus, we found that 2-methyl propanol was the only alcohol that was not related with amino acids while butanol was highly correlated with tyrosine (0.89) and taurine (0.93). Table 4 shows the correlation values between alcohols and amino acids. Ethanol showed a fine correlation exclusively with creatine for all the analyzed locations while 3-methyl-1-butanol was highly correlated with tyrosine (0.92). Creatine was also well correlated with 2-heptanol (0.92) and 1-octen-3-ol (0.93).