**4. Conclusions**

The application of blanching, saline immersion, and ultrasound pretreatment had significant effects on the drying characteristics, 3D appearance, quality characteristics, and microstructure of the potato slices. The results showed that pretreatment significantly enhanced the drying process of the potato slices and affected the 3D appearance during drying. All the pretreatment methods reduced the shrinkage during the drying process relative to the untreated potatoes. The curling degree was quantitatively characterized by height standard deviation (HSD). The results showed that the saline immersion and blanching pretreatments inhibited the curling of the potato slices, while the ultrasound pretreatment greatly aggravated the curling.

Through the quality analysis of the dried potato slices, it was found that the color difference value, total polyphenol content, and antioxidant activity of the potato slices were significantly different under the different pretreatment conditions. The blanching pretreatment could significantly inhibit color deterioration and maintain a higher total polyphenol content and antioxidant activity. Although the blanching pretreatment could significantly improve the nutritional quality and color of the potato slices, it could not significantly reduce the curling degree. Therefore, blanching pretreatment combined with saline immersion may be an optimal alternative pretreatment method for potato slice drying.

The microstructures of the dried potato slices were observed and analyzed by SEM. The microstructures of the dried potato slices were significantly changed under the different pretreatments, which was helpful in understanding and verifying the effects of pretreatment on the drying kinetics and appearance deformation. In addition, the mechanism of the 3D appearance changes caused by pretreatment needs to be further studied. This paper can provide a certain reference for the 3D appearance change and control of agricultural products during the drying process.

**Author Contributions:** Conceptualization, J.-W.B. and X.-Y.T.; data curation, J.-W.B. and Y.D.; formal analysis, Y.D.; funding acquisition, J.-R.C.; investigation, J.-W.B., Y.D. and Y.-C.W.; methodology, Y.-C.W. and X.-Y.T.; project administration, X.-Y.T.; resources, L.Z.; software, Y.-C.W. and L.Z.; supervision, X.-Y.T.; validation, Y.-C.W.; visualization, Y.D. and L.Z.; writing—original draft, J.-W.B. and Y.D.; writing—review and editing, J.-W.B. and X.-Y.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Jiangsu Key R&D Program (Modern Agriculture), Grant No: BE2019319.

**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.
