# Characterization of Quality Properties in Spoiled Mianning Ham
## 3 Results and Discussion
### Fungal Diversity Analysis  
The fungal \(\alpha\)-diversity indices of normal and spoiled Mianning ham are shown in Table 3. A total of nine samples were tested in the project. The data volume of raw reads in the sequencing down machine was distributed between 78,310-81,617, and the data volume of clean tags after quality control was distributed between 14,512-50,512. The valid tags (the data finally used for analysis) were obtained after noise reduction and removal of chimeras using DADA2 in QIIME2 [37]. The data volume is distributed between 14,512-50,436. Each de-duplicated sequence is called ASVs, and the number of ASVs in each sample is distributed between 7 and 40. A Venn diagram (Figure 3) was used to analyze and compare the common and unique ASVs among and within groups to preliminarily understand the ASV characteristics among groups. Three ham samples had a total of seven fungal ASVs. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Samples** & **Reads** & **ASV Counts** & **Observed Species** & **Chao1** & **Shannon** & **Simpson** & **Good’s Coverage** \\ \hline FBS & 79550 \(\pm\) 1151 a & 33 \(\pm\) 8 a & 32.43 \(\pm\) 7.84 a & 32.64 \(\pm\) 8 a & 1.09 \(\pm\) 0.31 a & 0.293 \(\pm\) 0.123 a & 0.999 \\ FBQ & 80481 \(\pm\) 1600 a & 25 \(\pm\) 3 a & 25.23 \(\pm\) 2.93 a & 25.33 \(\pm\) 3.06 a & 2.74 \(\pm\) 0.23 b & 0.772 \(\pm\) 0.046 b & 0.999 \\ ZC & 80728 \(\pm\) 771 a & 12 \(\pm\) 5 b & 12.07 \(\pm\) 5 b & 12.07 \(\pm\) 5 b & 1.69 \(\pm\) 0.68 ab & 0.464 \(\pm\) 0.297 ab & 0.999 \\ \hline \hline \end{tabular}
\begin{tabular}{c c c c c c} \hline \hline  & & Variance \(t\)-test: \(p>0.05\) was not non-significant, 0.05 \(>p>0.01\) was significant; \(p<0.01\) was extremely significant. Different letters between groups indicate significant differences. Means in the same column with different superscripts (a, b) are significantly different (\(p<0.05\)).  
\end{table} 
Table 3: Fungal alpha diversity index of normal and spoiled Mianning ham. Figure 2: Relative abundance of bacterial community proportions at the phylum (**a**) and genus (**b**) levels in Mianning ham. Different colors represent different bacterial communities, and the size of the color area represents the relative abundance (percentage) of bacterial community at the phylum (**a**) and genus (**b**). There was a significant difference (\(p<0.05\)) in the number and abundance index of ASVs between normal ham and two different levels of spoiled ham, indicating that more fungal species were present in deeply spoiled ham and surface spoiled ham than in normal ham. There was a significant difference (\(p<0.05\)) in the diversity index between deeply spoiled ham and surface spoiled ham and normal ham, indicating that the fungal community in deeply spoiled ham was higher than that in surface spoiled ham and normal ham. The fungal coverage of both spoiled and normal ham samples was 0.999, indicating that the method has basically covered the fungal community diversity and the measured data can be used for subsequent analysis. To further investigate the spoilage mechanism of Mianning ham and to understand the differences in fungal communities between different levels of spoiled ham and normal ham, this experiment was conducted to statistically analyze the fungal community composition of Mianning ham at both phylum and genus levels. The fungal abundance was visualized in the form of a stack diagram. At the phylum level (Figure 4a), Ascomycota, Basidiomycota and Glomeromycota were identified. Among them, Ascomycota accounted for 98.48%, 72.74%, and 92.81% in deeply spoiled ham, surface spoiled ham, and normal ham, respectively, and was the dominant phylum in all three ham samples. Ascomycota was the dominant phylum in the superficial and internal fungal communities of normal Mianning ham, accounting for 99.72% (superficial) and 97.49% (internal) of the total number of fungi, respectively, followed by Basidiomycota, which is close to the results of the present assay [38].