*3.10. Microbiological Analysis*

During the processing and storage of sausage, microorganisms would lead to the decomposition of protein and fat, leading to rot and rancidity, which is harmful to food safety. Therefore, the total number of bacterial colonies was recognized as an important parameter to evaluate the shelf-life stability [44]. The microbiological analysis of sausages in the control group and supplement groups were tested after 0, 5, 10, 15, and 20 days of storage (Table 9). The total number of bacterial colonies in each group increased significantly after 20 days of storage (*p* < 0.05). Compared to the supplement groups and the control group, there was no significant difference in the total number of bacterial colonies of sausage, indicating that PO had no significant effect on the total number of bacterial colonies of sausage. According to the existing national standards of China (1 × 105 CFU/g) (GB2726—2016), the sausages expired after 20 days. The sausage prepared in this study was steamed sausage, which was not Chinese sausage and this kind of product normally has a high water content and short shelf life. Therefore, it is acceptable for the product to expire after 20 days.

**Days Control PO10 PO20 PO30 PO40** 0 0.43 <sup>±</sup> 0.30 <sup>a</sup> 0.44 <sup>±</sup> 0.29 <sup>a</sup> 0.45 <sup>±</sup> 0.22 <sup>a</sup> 0.44 <sup>±</sup> 0.20 <sup>a</sup> 0.42 <sup>±</sup> 0.30 <sup>a</sup> 5 0.86 <sup>±</sup> 0.20 <sup>a</sup> 0.65 <sup>±</sup> 0.22 <sup>a</sup> 0.73 <sup>±</sup> 0.11 <sup>a</sup> 0.87 <sup>±</sup> 0.19 <sup>a</sup> 0.76 <sup>±</sup> 0.14 <sup>a</sup> 10 1.24 <sup>±</sup> 0.61 <sup>a</sup> 1.43 <sup>±</sup> 0.41 <sup>a</sup> 1.54 <sup>±</sup> 0.36 <sup>a</sup> 1.67 <sup>±</sup> 0.21 <sup>a</sup> 1.85 <sup>±</sup> 0.62 <sup>a</sup> 15 3.87 <sup>±</sup> 0.20 <sup>a</sup> 3.94 <sup>±</sup> 0.11 <sup>a</sup> 3.97 <sup>±</sup> 0.10 <sup>a</sup> 3.84 <sup>±</sup> 0.10 <sup>a</sup> 3.76 <sup>±</sup> 0.20 <sup>a</sup> 20 5.12 <sup>±</sup> 0.46 <sup>a</sup> 5.32 <sup>±</sup> 0.42 <sup>a</sup> 5.34 <sup>±</sup> 0.41 <sup>a</sup> 5.36 <sup>±</sup> 0.39 <sup>a</sup> 5.57 <sup>±</sup> 0.45 <sup>a</sup>

**Table 9.** Microorganisms of *Pleurotus ostreatus* (PO) pork sausages (log CFU/g).

<sup>a</sup> Means within the same row with different letters differ significantly among the treatments (*p* < 0.05). Values are given as mean ± standard error. Control, PO10, PO20, PO30, and PO40 were 0 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, and 40% addition of PO puree, respectively.

### **4. Conclusions**

A novel pork sausage incorporated with *Pleurotus ostreatus* (PO) puree was produced in this study. The PO improved the content of moisture and amino acids, lightness, springiness, and water holding capacity of the sausage while reducing the content of protein, fat, and ash, pH, redness, hardness, gumminess, and chewiness. For the sensory, the best formulation for the addition of PO was 20 wt.%, which not only enhanced the appearance and overall acceptability, but also gave it a better aroma and flavor. During 15 days of storage, the content of residual nitrite in the sausages decreased by 24.7~37.35%, and the TBARs value of the sausages was decreased by 4.76~32.14% compared with that of the control. Based on these results, the PO pork sausage in this study was successfully developed to enhance the quality and nutritional value and reduce the residual nitrite content and lipid oxidation during the storage of sausage. PO could be a competitive solution to improve flavor, safety, and overall quality of the sausages.

**Author Contributions:** Method, Writing—original draft, Data curation, X.W.; Writing—original draft, Writing—review and editing, Visualization, P.W.; Investigation, Q.X.; Investigation, B.J.; Writing original draft, L.L.; Data curation, L.R.; Investigation, Data curation, X.L.; Writing—review and editing, Project administration, Supervision, L.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Plan of Science and Technology Development of Jilin Province of China (No. 20210202066NC) and the Opening Project of Engineering Research Center of Edible and Medicinal Fungi (Ministry of Education), Jilin Agricultural University (No. JJJW2021001).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
