## 3 Results and Discussion
### Lipid Oxidation Analysis  
To examine the quality difference between spoiled and normal hams, we analysed the degree of lipid oxidation (Table 1). Lipid oxidation may alter the colour, flavour, texture, and nutritional content of foods ([PERSON] et al., 2016). Within the same muscle, the spoiled hams exhibited significantly higher TBARS values compared to the normal hams (\(p<0.05\)). Generally, a TBARS value below one is considered acceptable for lipid oxidation; a TBARS value above one suggests excessive oxidation, potentially leading to rancidity in meat products ([PERSON] et al., 2016). In this study, the low TBARS value in normal ham indicated a low degree of oxidation, which contributed to the unique aroma of Xuanwei ham. The high TBARS value of spoiled ham, indicating a higher degree of lipid oxidation, produced a strong rancid flavour, which may be one of the reasons for the off-flavour of spoiled hams ([PERSON] et al., 2016). Similar results were observed in the Jinhua hams (2016) and Mianning hams (2015), demonstrating significantly higher TBARS value in spoiled hams compared to those in normal hams. Generally, the  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{2}{c}{**Normal Ham**} & \multicolumn{2}{c}{**Spoiled Ham**} \\ \cline{2-5}  & **BF** & **SM** & **BF** & **SM** \\ \hline Moisture (g/100g) & 46.88 \(\pm\) 0.21 \({}^{\text{Ba}}\) & 39.44 \(\pm\) 0.59 \({}^{\text{Rb}}\) & 56.32 \(\pm\) 4.06 \({}^{\text{A}}\) & 49.98 \(\pm\) 2.37 \({}^{\text{Ab}}\) \\ \(a_{\text{w}}\) & 0.75 \(\pm\) 0.00 \({}^{\text{Ba}}\) & 0.74 \(\pm\) 0.00 \({}^{\text{Ba}}\) & 0.88 \(\pm\) 0.00 \({}^{\text{A}}\) & 0.87 \(\pm\) 0.00 \({}^{\text{A}}\) \\ pH & 5.74 \(\pm\) 0.01 \({}^{\text{Rb}}\) & 5.79 \(\pm\) 0.01 \({}^{\text{Ba}}\) & 6.63 \(\pm\) 0.01 \({}^{\text{Ab}}\) & 6.45 \(\pm\) 0.01 \({}^{\text{A}}\) \\ NaCl (\% of dry matter) & 14.09 \(\pm\) 2.10 \({}^{\text{A}}\) & 9.44 \(\pm\) 0.68 \({}^{\text{Ab}}\) & 9.92 \(\pm\) 1.12 \({}^{\text{Ba}}\) & 6.31 \(\pm\) 0.88 \({}^{\text{Rb}}\) \\ TBARS (mg MDA/kg) & 0.31 \(\pm\) 0.00 \({}^{\text{Rb}}\) & 0.46 \(\pm\) 0.01 \({}^{\text{Ba}}\) & 1.84 \(\pm\) 0.01 \({}^{\text{Ab}}\) & 1.98 \(\pm\) 0.01 \({}^{\text{A}}\) \\ \hline \hline \end{tabular} Different uppercase letters (A,B) indicate significant differences between hams with different quality grades for the same muscle (\(p<0.05\)), and different lowercase letters (a,b) indicate significant differences between different muscles for the ham with the same quality grade (\(p<0.05\)). SM: Semimembranosus; BF: Biceps femoris; TBARS: lipid oxidation was assessed by thiobarbituric acid reactive substances; Results expressed as mean \(\pm\) standard deviation (\(n=6\)).  
\end{table}
Table 1: Physicochemical properties of different muscles in normal and spoiled hams.  
development of lipid oxidation in dry-cured hams relies on a number of factors, such as the raw material composition and characteristics, the processing conditions and the amount and type of additives and ingredients added to the product [50]. In this study, the difference between the spoiled ham and the normal ham might have correlations with the materials and processing environment [51]. Within the same quality grade, the TBARS value of SM was significantly higher than that of BF (\(p<0.05\)). This higher TBARS value in SM could stem from its surface location, increasing its exposure to oxygen and susceptibility to oxidation [52]. These results affirm TBARS as a crucial indicator for assessing the quality of both spoiled and normal hams [53].