# Flavour Compensation Role of Yeast Strains in Reduced-Salt Dry Sausages: Taste and Odour Profiles
## 3 Results and Discussion
### Volatile Compound Analysis
Since hexanal and nonanal are derived from the oxidation of n-6 and n-9 polyunsaturated fatty acid oxidation [48], respectively, they gradually accumulated during the 12-day fermentation period and became the two most abundant aldehydes in the sausages. Hexanal, a typical indicator to evaluate lipid oxidation levels [49] that imparts grass, tallow, and fat flavours to meat products [50], was significantly higher in the PK and DH treatments compared to the controls (\(p<0.05\)). Tridecanal, which is linked to floral and sweet flavours, was present in all sausages but its content increased significantly in yeast-inoculated sausages (\(p<0.05\)), which is due to lipid oxidation [51]. Ketones are derived from the microbial enzymatic breakdown of lipids or amino acids or by the Maillard reaction [52]. A total of five ketones were detected in the sausages, of which only 3-hydroxy-2-butanone and 2-nonanone were detected in all sausages. 3-Hydroxy-2-butanone is derived from carbohydrate metabolism, whereas 2-nonanone is derived from lipid beta-oxidation. These two methyl ketones are considered characteristic fermented flavour compounds [47]. However, yeast inoculation did not affect the contents of these compounds in the sausages regardless of treatment (\(p>0.05\)). A total of 12 alcohols were detected, which originated from carbohydrate metabolism, reduction of methyl ketones and aldehydes, amino acid metabolism, and lipid oxidation [53; 54]. Ethanol, a common alcohol in dry fermented sausages, mainly comes from the wine that is added during sausage preparation. However, this compound can accumulate via the  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & \multicolumn{2}{c}{**Volatile**} & \multicolumn{2}{c}{**CAS**} & \multicolumn{2}{c}{**LRI**} & \multicolumn{2}{c}{**CT-0d**} & \multicolumn{2}{c}{**CT-12d**} & \multicolumn{2}{c}{**CR-12d**} & \multicolumn{2}{c}{**PK-12d**} & \multicolumn{2}{c}{**TD-12d**} & \multicolumn{2}{c}{**DH-12d**} \\  & \multicolumn{2}{c}{**Esters**} & & & & & & & & & & \\ V28 & Ethyl acetate & 141.78-6 & 907 & 1.21 \(\pm\) 0.13 \({}^{a}\) & 4.07 \(\pm\) 0.25 \({}^{a}\) & 18.45 \(\pm\) 0.93 \({}^{b}\) & 16.34 \(\pm\) 0.99 \({}^{b}\) & 23.12 \(\pm\) 1.12 \({}^{a}\) & 11.87 \(\pm\) 0.66 \({}^{c}\) \\ V29 & Ethyl acetate & 97.64-3 & 1358 & n.d. & n.d. & 5.13 \(\pm\) 0.44 \({}^{a}\) & 20.27 \(\pm\) 0.76 \({}^{b}\) & 21.42 \(\pm\) 0.85 \({}^{b}\) & 32.52 \(\pm\) 0.61 \({}^{c}\) \\ V30 & Methyl lustrate & 623-27 & 963 & n  
alcoholic fermentation of glucose or the pentose-phosphate route [53]. Ethanol levels remained higher than those of other alcohols throughout the fermentation process but decreased significantly after fermentation (except in the DH treatment), which was likely due to its conversion to esters via interaction with acids [55]. The ethanol content increased significantly in the DH treatment (\(p<0.05\)) and the same phenomenon was also confirmed in'salchichon' sausages after inoculation with \(D\). _hansenii_[56], which was likely due to the strong ability of \(D\). _hansenii_ to produce alcohols from the metabolism of carbohydrates and branched-chain amino acids [57]. Furthermore, 1-octen-3-ol is an odorant with a mushroom-like flavour that is usually present in meat products [54]. The content of this compound increased significantly after fermentation (\(p<0.05\)). On day 12, the PK, TD, and DH treatments exhibited higher content compared to the controls (\(p<0.05\)). Further, some alcohols from spices such as linalool and cineole provide dry sausages with characteristic citrus and herbal odours, respectively, and are also important aroma compounds. Six acids were found in dry sausages, of which acetic and butanoic acids were derived from carbohydrate fermentation, whereas octanoic and nonanoic acids were derived from lipid oxidation [58]. Acids were represented mainly by acetic acid, which can contribute to the typical aroma of meat products, especially dry fermented products [59].