## 4 Conclusions  
In this study, the effects of the microwave vacuum drying technological parameters on the sensory quality and nutrient quality of the mulberry drying were studied through single-factor and multi-factor tests. Some conclusions can be drawn:  
1. According to the analysis of the single-factor test results, the material surface temperature, vacuum degree, and microwave power had significant influences on the drying quality of the mulberry (\(p<0.05\)).
2. The comprehensive scores of the single-factor test factors were compared against the membership function model. The best mulberry quality was achieved when the material surface temperature was 46.0-54.0 \({}^{\circ}\)C, the vacuum degree was 0.05-0.09 MPa, and the microwave power was 300-500 W.
3. The following optimal parameter combinations for the microwave vacuum drying technology was obtained through a central composite test design: material surface temperature--50.761 \({}^{\circ}\)C, vacuum degree--0.073 MPa, and microwave power--370.558 W. Under the optimal parameters, the soluble solid content, chewiness, and Vc content were 43.967%, 9.701, and 0.785 mg-(100 g)\({}^{-1}\), respectively. To eliminate random errors, the test parameters were optimized, and the integral values were chosen as follows: material surface temperature--51 \({}^{\circ}\)C, vacuum degree--0.07 MPa, and microwave power--370 W. Under these conditions, the soluble solid content was 42.37%, chewiness was 9.08, and Vc content was 0.725 mg-(100 g)\({}^{-1}\). The average error between the test results and software optimization parameters was 5.88%, thereby indicating that the optimized technological parameters can improve the drying quality of mulberry.  
An optimized technological parameter combination of microwave vacuum drying can effectively decrease nutrient loss and improve the drying quality of mulberry. It can provide references for the practical initial processing technology of mulberry, as well as offer some theoretical references to further understand the importance of the drying of mulberry.  
Conceptualization, H.Z. and Y.C.; methodology, Y.C.; software, Y.C.; validation, Y.T.; formal analysis, Y.L.; investigation, Y.C.; resources, H.Z.; data curation, Y.C.; writing--original draft preparation, Y.C.; writing--review and editing, H.Z. and Y.L.; visualization, Z.L. and X.Y.; supervision, H.Z. and Y.L.; project administration, J.M. ([PERSON]) and J.M. ([PERSON]); funding acquisition, H.Z. All authors have read and agreed to the published version of the manuscript.  
This research was financially supported by the Tarim University Graduate Research Innovation Project (TDGRI202246): Dynamics and Quality Analysis of Mulberry Microwave Vacuum Drying; the Chinese Natural Science Foundation (12002229, 31160196), the President's Foundation of Tarim University (TDZKBS202001), the Open Project of the Modern Agricultural Engineering Key Laboratory (TDNG2022101, TDNG2021104), and the Shishi Science and Technology Program (Grant No. 2021 ZB01).  
Not applicable.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Serial Number** & **Soluble Solid \%** & **Chewiness** & **Vc mg-(100 g)\({}^{-1}\)** \\ \hline
1 & 42.26 & 9.18 & 0.725 \\
2 & 42.32 & 8.92 & 0.73 \\
3 & 42.53 & 9.14 & 0.719 \\ Average value & 42.37 & 9.08 & 0.725 \\ \hline \hline \end{tabular}
\end{table}
Table 14: The test results of the optimization parameters.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors on request.  
**Acknowledgments:** The authors thank [PERSON] from Tarm University for their thesis supervision. The authors are grateful to the anonymous reviewers for their comments.  
**Conflicts of Interest:** The authors declare no conflicts of interest.