# Characterization of Quality Properties in Spoiled Mianning Ham
## 3 Results and Discussion  
### Physical and Chemical Index Analyses  
Physicochemical characteristics are closely related to the quality of ham, and the physicochemical indices of deeply spoiled ham, surface spoiled ham, and normal ham are shown in Table 1.  
The moisture content of deeply spoiled ham (44.7 \(\pm\) 1.032 g/100 g) was significantly higher than that of surface spoiled ham (39.99 \(\pm\) 0.146 g/100 g) and normal ham (38.85 \(\pm\) 0.33 g/100 g) (\(p\) < 0.05), due to the way Mianning ham is preserved (natural hanging) resulting in a soft interior and a hard exterior, with a higher moisture content inside than on the surface. The higher moisture content may be one of the causes of ham spoilage. The moisture content of spoiled dry-cured Spanish ham was higher than that of normal ham, which is close to the results of this study [22]. Water activity (a\({}_{\rm w}\)) refers to the state of the presence of water in the food and the degree of water binding to the food. Most of the water activity in fresh meat is above 0.98, and various microorganisms grow and multiply vigorously. The a\({}_{\rm w}\) of deeply spoiled ham was 0.945 \(\pm\) 0.042, which was significantly higher than that of surface spoiled ham (0.88 \(\pm\) 0.007) and normal ham (0.852 \(\pm\) 0.006) (\(p\) < 0.05). Studies have shown that dry-cured hams are more susceptible to microbial contamination at when a\({}_{\rm w}\) > 0.91, and it is necessary to reduce aw or keep aw at 0.9 to inhibit the growth of most bacteria [23]. Studies have shown that when pH > 6.0, ham is more susceptible to microbes [24]. The pH values of deeply spoiled and surface spoiled ham were 6.51 \(\pm\) 0.15 and 6.31 \(\pm\) 0.01, respectively, which was significantly higher than the normal ham (5.93 \(\pm\) 0.15) (\(p\) < 0.05). A higher pH value is one of the indicators of spoilage of meat products. The pH of St. Daniel's spoiled ham is 6.5 \(\pm\) 0.3, and the pH of the undenatured ham was 5.9 \(\pm\) 0.2, which is closer to the present determination of the Mianning ham [25]. Ham will have a better color and texture when the pH is between 5.6 and 6.0 during the processing [26]. The chloride content of deeply spoiled ham was 5.18 \(\pm\) 0.3 g/100 g, which was significantly lower than that of surface spoiled ham (6.16 \(\pm\) 0.17 g/100 g) and normal ham (8.29 \(\pm\) 0.38 g/100 g) (\(p\) < 0.05). The low chloride content may be related to the salting process of Mianning ham, where salt is applied to the surface of the ham during curing. The surface salt has difficulty penetrating into the interior of the ham. The inside of ham with low salt concentration with high a\({}_{\rm w}\) very easily leads to deep spoilage. Lower chloride concentrations lead to excessive protein hydrolysis, implying higher tissue enzyme activity. It has been shown that the 5-6% salt content of dry-cured ham completely inhibited the activity of calcium-activating factor and tissue proteinase D in biceps femoris and semimembranosus muscles [27]. The lower salt content may also lead to an increase in pH. The higher the pH, the better the ham's ability to hold water, which is one of the reasons why the moisture content of spoiled ham is higher than normal ham. A study confirmed