**5. Conclusions**

Our study demonstrated that the sweetness index, antioxidant activity, amino acid content, and sensory characteristics of postharvest mature sweet potato tuberous roots were significantly improved after 14 d of storage at 5 ◦C without any indications of CI, but a continued extension of CS time would lead to cold injury, resulting in the decline of storage tolerance. The key genes associated with sweet potato quality parameters were also identified through RNA-Seq and verified using qPCR, and exhibited the involvement of sucrose synthase and sucrose phosphate synthase in starch and sucrose metabolism pathway, phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, and hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase in phenylpropane biosynthesis pathway and serine hydroxymethyltransferase, alanine aminotransferase, arogenate dehydrogenase and prephenate dehydratase in the biosynthesis of amino acids pathway, thus providing insights into the molecular mechanisms by which short-term cold storage enhances sweet potato quality and nutritional profile. Therefore, short-term CS treatment is an effective method to improve the nutritional and sensory quality of sweet potato tuberous roots.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/ 10.3390/foods10092079/s1, Table S1: Primers for Quantitative Real-time PCR, Table S2: Sample sequencing data evaluation statistics table, Table S3: Statistical table of comparison results between the second-generation sequencing data and the reference genome, Table S4: Annotation statistics table of single gene sequence, Table S5: Statistics of the number of annotations for differentially expressed genes, Table S6: Comparison table of GO function annotations of differentially expressed genes, Table S7: Function annotation comparison table of differentially expressed gene KEGG, Figure S1: Statistical chart of GO annotation classification of DEGs, Figure S2: KEGG classification map and KEGG enrichment map of DEGs.

**Author Contributions:** Conceptualization, Y.L. and H.Y.; Data curation, G.C.; Investigation, S.Z. and L.C.; Writing—original draft, S.Z. and L.C. S.Z. and L.C. contributed equally to this work. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (No. 31871857) and the Zhejiang Provincial Natural Science Foundation of China (No. LQ20C200002).

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** All authors thank Yanrong Huo and Peng Cui for helping to illustrate the graphical abstract.

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