# Optimization of Vacuum Freeze-Drying Process and Quality Evaluation of _Stropharia rugosanmulata_
## 4 Conclusions  
This experiment determined the optimal parameters for the vacuum freeze-drying of _Stropharia rugososanmulata_: a pre-freezing temperature of \(-80\)\({}^{\circ}\)C, a pre-freezing time of 48 h, a freeze-drying time of 72 h, a vacuum pressure of 0.7 mbar, and a slice thickness of 2 mm. Further variance analysis also revealed the order of influence: pre-freezing temperature \(>\) pre-freezing time \(>\) freeze-drying time. The color of the slices is an important indicator for \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline \multirow{2}{*}{**Sample Name**} & \multicolumn{1}{c}{**A**} & \multicolumn{1}{c}{**B**} & \multicolumn{1}{c}{**C**} & & & \\ \cline{2-9}  & \multicolumn{1}{c}{**Pre-Freezing Temperature/\({}^{\circ}\)C**} & \multicolumn{1}{c}{**Pre-Freezing Time/h**} & \multicolumn{1}{c}{**Freezing Time/h**} & \multicolumn{1}{c}{**Sensory Score/40**} & \multicolumn{1}{c}{**Rehydration Rate**} & \multicolumn{1}{c}{**Protein Content Score/30**} & \multicolumn{1}{c}{**Comprehensive Score**} \\ \hline A\({}_{1}\)B\({}_{1}\)C\({}_{1}\) & \(-20\) & 48 & 60 & 28.33 & 30 & 26.89 & 85.22 \\ A\({}_{1}\)B\({}_{2}\)C\({}_{2}\) & \(-20\) & 60 & 72 & 28.66 & 26.33 & 28.71 & 83.70 \\ A\({}_{1}\)B\({}_{3}\)C\({}_{3}\) & \(-20\) & 72 & 84 & 33.67 & 24.3 & 26.67 & 84.64 \\ A\({}_{2}\)B\({}_{1}\)C\({}_{3}\) & \(-40\) & 48 & 84 & 29.66 & 25.69 & 26.01 & 81.36 \\ A\({}_{2}\)B\({}_{2}\)C\({}_{1}\) & \(-40\) & 60 & 60 & 28.66 & 20.76 & 28.53 & 77.95 \\ A\({}_{2}\)B\({}_{3}\)C\({}_{2}\) & \(-40\) & 72 & 72 & 33.67 & 20.76 & 27.99 & 82.42 \\ A\({}_{3}\)B\({}_{1}\)C\({}_{2}\) & \(-80\) & 48 & 72 & 33.67 & 27.35 & 27.52 & 88.54 \\ A\({}_{3}\)B\({}_{2}\)C\({}_{3}\) & \(-80\) & 60 & 84 & 30.33 & 30 & 27.05 & 87.38 \\ A\({}_{3}\)B\({}_{3}\)C\({}_{1}\) & \(-80\) & 72 & 60 & 33.67 & 27.05 & 26.9 & 87.62 \\ \hline K\({}_{1}\) & & 253.56 & 255.12 & 250.79 & & & & T = 758.83 \\ K\({}_{2}\) & & 241.73 & 249.03 & 254.66 & & & & \\ K\({}_{3}\) & & 263.54 & 254.68 & 253.38 & & & & \\ k\({}_{1}\) & & 84.52 & 85.04 & 83.60 & & & & \\ k\({}_{2}\) & & 80.58 & 83.01 & 84.89 & & & \\ k\({}_{3}\) & & 87.85 & 84.89 & 84.46 & & & \\ R & & 7.27 & 2.03 & 1.29 & & & \\ Superior level & A\({}_{3}\) B\({}_{1}\) C\({}_{2}\) & & & & & & \\ Importance of Factors & A \(>\) B \(>\) C & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Orthogonal experiment and scoring results. evaluating product quality and directly affects consumer acceptance of the product. The optimized process produces _Stropharia rugosaannulata_ slices that rarely brown and retain their natural white color even after drying. The product has a moderate thickness, making it convenient to carry and consume. The _Stropharia rugosaannulata_ slices were treated with the natural bioactive antimicrobial peptide nisin, ensuring safety and healthiness. They retained their original aroma and nutritional components; are ready-to-eat, convenient, and safe; and exhibit excellent rehydration properties. Nutritionally, the freeze-dried products have a significantly higher protein content compared to hot air-dried products. This can be attributed to the lower temperatures and vacuum conditions used in freeze-drying, which help minimize protein degradation [34]. The soluble protein content of the vacuum freeze-dried _Stropharia rugosaannulata_ reached 68 mg/g. Through experimentation, the following patterns were observed under different pretreatment conditions: A better freeze-drying effect of _Stropharia rugosaannulata_ is seen at lower pre-freezing temperatures. A pre-freezing time that is too short may lead to insufficient pre-freezing or browning of _Stropharia rugosaannulata_, affecting subsequent sensory scores. Good freeze-drying results can be achieved within a relatively short pre-freezing time.